diff --git a/src/classes/Entities/Collection.php b/src/classes/Entities/Collection.php
index e049d07c3..4128b752d 100644
--- a/src/classes/Entities/Collection.php
+++ b/src/classes/Entities/Collection.php
@@ -104,6 +104,11 @@ class TainacanCollection extends Entity  {
         return $this->get_id() ? 'tnc_col_' . $this->get_id() : false;
     }
     
+    // metadata
+    function get_metadata() {
+        global $Tainacan_Metadatas;
+        return $Tainacan_Metadatas->get_metadata_by_collection($this);
+    }
     
     // Setters
     // 
@@ -126,21 +131,5 @@ class TainacanCollection extends Entity  {
     function set_itens_per_page($value) {
         return $this->set_mapped_property('itens_per_page', $value);
     }
-    
-    
-    // Relation methods
-    
-    
-    
-    
-    
-    
-    
-    
-    function get_metadata( $collection ){
-        global $Tainacan_Metadatas;
-        return $Tainacan_Metadatas->get_collection_metadata( $collection );
-    }
-    
-    
+
 }
\ No newline at end of file
diff --git a/src/classes/Entities/Item.php b/src/classes/Entities/Item.php
index a483af02f..ac7eac1f0 100644
--- a/src/classes/Entities/Item.php
+++ b/src/classes/Entities/Item.php
@@ -48,15 +48,7 @@ class TainacanItem extends Entity {
     }
     
 
-    function get_metadata(){
-        global $TainacanItems;
 
-        if(isset($this->metadata)) {
-            return $this->metadata;
-        }
-
-        return $TainacanItems->get_metadata( $this );
-    }
     
     // Setters
     // 
@@ -73,16 +65,39 @@ class TainacanItem extends Entity {
     function set_description($value) {
         return $this->set_mapped_property('description', $value);
     }
-    
-    
-    // sepecial Setters
-    
-    
 
 
-    function set_metadata( $metadata ){
-
+    // Metadata
+    
+    function get_metadata() {
+        if (isset($this->metadata))
+            return $this->metadata;
+        
+        $collection = $this->get_collection();
+        $return = [];
+        if ($collection) {
+            $metaList = $collection->get_metadata();
+            
+            foreach ($metaList as $meta) {
+                $return[$meta->get_id()] = new Tainacan_Item_Metadata_Entity($this, $meta);
+            }
+        }
+        return $return;
     }
     
+    function add_metadata(Tainacan_Metadata $new_metadata, $value) {
+        
+        //TODO Multiple metadata must receive an array as value
+        
+        $item_metadata = new Tainacan_Item_Metadata_Entity($this, $new_metadata);
+        $item_metadata->set_value($value);
+        $current_meta = $this->get_metadata();
+        $current_meta[$new_metadata->get_id()] = $item_metadata;
+        $this->set_metadata($current_meta);
+    }
+    
+    function set_metadata(Array $metadata) {
+        $this->metadata = $metadata;
+    }
     
 }
\ No newline at end of file
diff --git a/src/classes/Entities/Item_Metadata_Entity.php b/src/classes/Entities/Item_Metadata_Entity.php
new file mode 100644
index 000000000..a3d780138
--- /dev/null
+++ b/src/classes/Entities/Item_Metadata_Entity.php
@@ -0,0 +1,158 @@
+<?php
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+
+
+
+
+class Tainacan_Item_Metadata_Entity extends Entity  {
+    
+    
+    function __construct(TainacanItem $item, Tainacan_Metadata $metadata) {
+        
+        $this->repository = 'Tainacan_Item_Metadata';
+        
+        $this->set_item($item);
+        $this->set_metadata($metadata);
+        
+    }
+    
+    function set_item(TainacanItem $item) {
+        $this->item = $item;
+    }
+    
+    function set_value($value) {
+        $this->value = $value;
+    }
+    
+    function set_metadata(Tainacan_Metadata $metadata) {
+        $this->metadata = $metadata;
+    }
+    
+    function get_item() {
+        return $this->item;
+    }
+    
+    function get_metadata() {
+        return $this->metadata;
+    }
+    
+    function get_value() {
+        
+        if (isset($this->value))
+            return $this->value;
+        
+        global $Tainacan_Item_Metadata;
+        return $Tainacan_Item_Metadata->get_item_metadata_value($this);
+    }
+    
+    
+    //////////////////
+    
+    function is_multiple() {
+        return $this->get_metadata()->is_multiple();
+    }
+    
+    function is_collection_key() {
+        return $this->get_metadata()->is_collection_key();
+    }
+    
+    function is_required() {
+        return $this->get_metadata()->is_required();
+    }
+    
+    function validate() {
+        
+        $value = $this->get_value();
+        $metadata = $this->get_metadata();
+        $item = $this->get_item();
+        
+        if (empty($value) && $this->is_required()) {
+            $this->add_error('required', $metadata->get_name() . ' is required');
+            return false;
+        }
+        
+        if ($this->is_multiple()) {
+            
+            if (is_array($value)) {
+                
+                // if its required, at least one must be filled
+                $one_filled = false;
+                $valid = true;
+                foreach($value as $val) {
+                    if (!empty($val))
+                        $one_filled = true;
+                    
+                    // TODO: call fieldtype validation
+                    // if (invalid) $valid = false;
+                    
+                }
+                
+                if ($this->is_required() && !$one_filled) {
+                    $this->add_error('required', $metadata->get_name() . ' is required');
+                    return false;
+                }
+                
+                if (!$valid) {
+                    $this->add_error('invalid', $metadata->get_name() . ' is invalid');
+                    return false;
+                }
+                
+                $this->reset_errors();
+                return true;
+                
+                
+            } else {
+                $this->add_error('invalid', $metadata->get_name() . ' is invalid');
+                return false;
+            }
+            
+            
+        } else {
+            
+            if ($this->is_collection_key()) {
+                global $TainacanItems;
+                $test = $TainacanItems->query([
+                    'collections' => $item->get_collection(),
+                    'metadata' => [
+                        [
+                            'key' => $this->metadata->get_id(),
+                            'value' => $value
+                        ]
+                    ]
+                ]);
+
+                if (!empty($test)) {
+                    $this->add_error('key_exists', $metadata->get_name() . ' is a collection key and there is another item with the same value');
+                    return false;
+                }
+            }
+            
+            // TODO: call fieldType validation
+            // 
+            $this->reset_errors();
+            return true;
+            
+        }
+        
+    }
+    
+    protected function validate_one_multiple_value($value) {
+        $metadata = $this->get_metadata();
+        
+        if (empty($value) && $this->is_required())
+            return false;
+        
+        // This method is only called for multiple Metadata
+        // therefore it can not be collection_key
+        
+        // TODO: call fieldType validation
+        
+        return true;
+        
+    }
+    
+    
+}
\ No newline at end of file
diff --git a/src/classes/Entities/Metadata.php b/src/classes/Entities/Metadata.php
index e4a536c74..b25aed37c 100644
--- a/src/classes/Entities/Metadata.php
+++ b/src/classes/Entities/Metadata.php
@@ -53,9 +53,21 @@ class Tainacan_Metadata extends Entity {
     }
 
 
+    function get_required(){
+        return $this->get_mapped_property('required');
+    }
+    
+    function get_multiple(){
+        return $this->get_mapped_property('multiple');
+    }
+    
     function get_cardinality(){
         return $this->get_mapped_property('cardinality');
     }
+    
+    function get_collection_key(){
+        return $this->get_mapped_property('collection_key');
+    }
 
     function get_mask(){
         return $this->get_mapped_property('mask');
@@ -100,9 +112,21 @@ class Tainacan_Metadata extends Entity {
     }
 
 
+    function set_required( $value ){
+        return $this->set_mapped_property('required', $value);
+    }
+    
+    function set_multiple( $value ){
+        return $this->set_mapped_property('multiple', $value);
+    }
+    
     function set_cardinality( $value ){
         return $this->set_mapped_property('cardinality', $value);
     }
+    
+    function set_collection_key( $value ){
+        return $this->set_mapped_property('collection_key', $value);
+    }
 
     function set_mask( $value ){
         return $this->set_mapped_property('mask', $value);
@@ -128,5 +152,19 @@ class Tainacan_Metadata extends Entity {
         return $this->set_mapped_property('option',  serialize($value) ) ;
     }
 
+    
+    // helpers
+    
+    function is_multiple() {
+        return $this->get_multiple() === 'yes';
+    }
+    
+    function is_collection_key() {
+        return $this->get_collection_key() === 'yes';
+    }
+    
+    function is_required() {
+        return $this->get_required() === 'yes';
+    }
 
 }
\ No newline at end of file
diff --git a/src/classes/Entity.php b/src/classes/Entity.php
index dd498861a..8b97006f3 100644
--- a/src/classes/Entity.php
+++ b/src/classes/Entity.php
@@ -4,10 +4,10 @@
 class Entity {
     
     var $repository;
+    var $errors = [];
     
     function get_mapped_property($prop) {
         
-        
         global ${$this->repository};
         $map = ${$this->repository}->map;
         
@@ -21,17 +21,21 @@ class Entity {
         $mapped = $map[$prop]['map'];
         
         if ( $mapped == 'meta') {
-            return get_post_meta($this->WP_Post->ID, $prop, true);
+            $return = get_post_meta($this->WP_Post->ID, $prop, true);
         }elseif ( $mapped == 'meta_multi') {
-            return get_post_meta($this->WP_Post->ID, $prop, false);
+            $return = get_post_meta($this->WP_Post->ID, $prop, false);
         }elseif ( $mapped == 'termmeta' ){
-            return get_term_meta($this->WP_Term->term_id, $prop, true);
+            $return = get_term_meta($this->WP_Term->term_id, $prop, true);
         }elseif ( isset( $this->WP_Post )) {
-            return isset($this->WP_Post->$mapped) ? $this->WP_Post->$mapped : null;
+            $return = isset($this->WP_Post->$mapped) ? $this->WP_Post->$mapped : null;
         } elseif ( isset( $this->WP_Term )) {
-            return isset($this->WP_Term->$mapped) ? $this->WP_Term->$mapped : null;
+            $return = isset($this->WP_Term->$mapped) ? $this->WP_Term->$mapped : null;
         }
         
+        if (empty($return) && isset($map[$prop]['default']) && !empty($map[$prop]['default']))
+            $return = $map[$prop]['default'];
+            
+        return $return;
     }
     
     function set_mapped_property($prop, $value) {
@@ -53,12 +57,20 @@ class Entity {
         
     }
 
-    function validate($value) {
+    function validate() {
         return true;
     }
     
-    function get_validation_errors() {
-        return [];
+    function get_errors() {
+        return $this->errors;
+    }
+    
+    function add_error($type, $message) {
+        $this->errors[] = [$type => $message];
+    }
+    
+    function reset_errors() {
+        $this->errors = [];
     }
         
 }
\ No newline at end of file
diff --git a/src/classes/FieldTypes/FieldType.php b/src/classes/FieldTypes/FieldType.php
index 6c38c0431..4f91de2e0 100644
--- a/src/classes/FieldTypes/FieldType.php
+++ b/src/classes/FieldTypes/FieldType.php
@@ -6,7 +6,15 @@ if ( ! defined( 'ABSPATH' ) ) {
 /**
  * Class TainacanFieldType
  */
-abstract class Tainacan_Field_Type extends Entity {
+abstract class Tainacan_Field_Type  {
 
     abstract function render( $metadata );
+    
+    function validate($value) {
+        return true;
+    }
+    
+    function get_validation_errors() {
+        return [];
+    }
 }
\ No newline at end of file
diff --git a/src/classes/Repositories/Collections.php b/src/classes/Repositories/Collections.php
index 186bb3450..f5a005018 100644
--- a/src/classes/Repositories/Collections.php
+++ b/src/classes/Repositories/Collections.php
@@ -84,7 +84,7 @@ class TainacanCollections {
         // First iterate through the native post properties
         $map = $this->map;
         foreach ($map as $prop => $mapped) {
-            if ($mapped['map'] != 'meta') {
+            if ($mapped['map'] != 'meta' && $mapped['map'] != 'meta_multi') {
                 $collection->WP_Post->{$mapped['map']} = $collection->get_mapped_property($prop);
             }
         }
@@ -114,7 +114,8 @@ class TainacanCollections {
         
         $collection->register_post_type();
         
-        return $id;
+        // return a brand new object
+        return new TainacanCollection($collection->WP_Post);
     }
     
     function get_collections($args = array()) {
diff --git a/src/classes/Repositories/ItemMetadata.php b/src/classes/Repositories/ItemMetadata.php
new file mode 100644
index 000000000..fe73297a3
--- /dev/null
+++ b/src/classes/Repositories/ItemMetadata.php
@@ -0,0 +1,61 @@
+<?php
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+
+
+class Tainacan_Item_Metadata {
+    
+    function get_item_metadata_by_item(TainacanItem $item) {
+        global $TainacanItems, $Tainacan_Metadatas;
+        
+        $collection = $item->get_collection();
+        
+        if (!$collection instanceof TainacanCollection)
+            return [];
+        
+        $meta_list = $Tainacan_Metadatas->get_metadata_by_collection($collection);
+        
+        $return = [];
+        
+        if (is_array($meta_list)) {
+            foreach ($meta_list as $meta) {
+                $return = new Tainacan_Item_Metadata_Entity($item, $meta);
+            }
+        }
+        
+        return $return;
+        
+    }
+    
+    function insert(Tainacan_Item_Metadata_Entity $item_metadata) {
+        
+        $unique = $item_metadata->get_metadata()->get_cardinality() > 1 ? false : true;
+        
+        if ($unique) {
+            update_post_meta($item_metadata->item->get_id(), $item_metadata->metadata->get_id(), $item_metadata->get_value());
+        } else {
+            delete_post_meta($item_metadata->item->get_id(), $item_metadata->metadata->get_id());
+            if (is_array($item_metadata->get_value())) 
+                foreach ($item_metadata->get_value() as $value)
+                    add_post_meta($item_metadata->item->get_id(), $item_metadata->metadata->get_id(), $value);
+        }
+        
+        // return a brand new object
+        return new Tainacan_Item_Metadata_Entity($item_metadata->get_item(), $item_metadata->get_metadata());
+        
+    }
+    
+    function get_item_metadata_value(Tainacan_Item_Metadata_Entity $item_metadata) {
+        
+        $unique = ! $item_metadata->is_multiple();
+            
+        return get_post_meta($item_metadata->item->get_id(), $item_metadata->metadata->get_id(), $unique);
+        
+    }
+    
+}
+
+global $Tainacan_Item_Metadata;
+$Tainacan_Item_Metadata = new Tainacan_Item_Metadata();
\ No newline at end of file
diff --git a/src/classes/Repositories/Items.php b/src/classes/Repositories/Items.php
index c0c7076b7..fe57e8616 100644
--- a/src/classes/Repositories/Items.php
+++ b/src/classes/Repositories/Items.php
@@ -79,13 +79,14 @@ class TainacanItems {
         
         // iterate through the native post properties
         foreach ($map as $prop => $mapped) {
-            if ($mapped['map'] != 'meta') {
+            if ($mapped['map'] != 'meta' && $mapped['map'] != 'meta_multi') {
                 $item->WP_Post->{$mapped['map']} = $item->get_mapped_property($prop);
             }
         }
         
         // save post and geet its ID
         $item->WP_Post->post_type = $cpt;
+        $item->WP_Post->post_status = 'publish';
         $id = wp_insert_post($item->WP_Post);
         $item->WP_Post = get_post($id);
         
@@ -102,45 +103,118 @@ class TainacanItems {
             }
         }
         
-        // TODO - save item medatada
-        // get collection Metadata
-        // foreach metadata...
+        // save metadata
+        $metadata = $item->get_metadata();
+        global $Tainacan_Item_Metadata;
+        foreach ($metadata as $meta) {
+            $Tainacan_Item_Metadata->insert($meta);
+        }
         
-        
-        return $id;
+        // return a brand new object
+        return new TainacanItem($item->WP_Post);
     }
     
+    // collections id or array of ids; collection object or array of objects
+    function get_items($args = array(), $collections = []) {
+        
+        global $TainacanCollections;
+        
+        if (empty($collections)) {
+            $collections = $TainacanCollections->get_collections();
+        }
+        
+        if (is_numeric($collections)) 
+            $collections = $TainacanCollections->get_collection_by_id($collection);
+        
+        if ($collections instanceof TainacanCollection) {
+            $cpt = $collections->get_db_identifier();
+        } elseif (is_array($collections)) {
+            $cpt = [];
+            
+            foreach ($collections as $collection) {
+                if (is_numeric($collection)) 
+                    $collection = $TainacanCollections->get_collection_by_id($collection);
+                
+                if ($collection instanceof TainacanCollection)
+                    $cpt[] = $collection->get_db_identifier();
+            }
+            
+        } else {
+            return [];
+        }
+        
+        if (empty($cpt))
+            return [];
+
+        $args = array_merge([
+            'post_type' => $cpt,
+            'posts_per_page' => -1,
+            'post_status' => 'publish',
+        ], $args);
+
+        $posts = get_posts($args);
+        
+        $return = [];
+        
+        foreach ($posts as $post) {
+            $return[] = new TainacanItem($post);
+        }
+        
+        return $return;
+    }
+    
+    // same as WP_Query with few paramaters more:
+    // collections ID or array of IDs, object or array of objects
+    // metadata - array of metadata in meta_query format
+    // other item properties, present in the "map"
+    function query($args) {
+        
+        $map = $this->map;
+        $wp_query_exceptions = [
+            'ID' => 'p',
+            'post_title' => 'title'
+        ];
+        
+        $meta_query = [];
+        
+        foreach ($map as $prop => $mapped) {
+            if (array_key_exists($prop, $args)) {
+                $prop_value = $args[$prop];
+                unset($args[$prop]);
+                if ( $mapped['map'] == 'meta' || $mapped['map'] == 'meta_multi' ) {
+                    $meta_query[] = [
+                        'key' => $prop,
+                        'value' => $prop_value
+                    ];
+                } else {
+                    $prop_search_name = array_key_exists($mapped['map'], $wp_query_exceptions) ? $wp_query_exceptions[$mapped['map']] : $mapped['map'];
+                    $args[$prop_search_name] = $prop_value;
+                }
+                
+            }
+        }
+        
+        if ( isset($args['metadata']) && is_array($args['metadata']) && !empty($args['metadata'])) {
+            $meta_query = $args['metadata'];
+        }
+        
+        $args['meta_query'] = $meta_query;
+        
+        unset($args['metadata']);
+        
+        $collections = !empty($args['collections']) ? $args['collections'] : [];
+        unset($args['collections']);
+        
+        return $this->get_items($args, $collections);
+        ### TODO I think its better if we return a WP_Query object. easier for loop and debugging
+        
+    }
    
     function get_item_by_id($id) {
         return new TainacanItem($id);
     }
 
 
-    function get_metadata( TainacanItem $item ){
-        global $TainacanCollections;
-        $values = [];
-
-        $collection_metadata = $TainacanCollections->get_metadata( $item->get_collection() );
-        foreach ($collection_metadata as $metadata) {
-            $values[] = [
-                'metadata_id' =>  $metadata->get_id(),
-                'value' => get_post_meta( $item->get_id(), $metadata->get_id()),
-            ];
-        }
-
-        return $values;
-    }
-
-
-    function set_metadata( TainacanItem $item, $values){
-        global $TainacanCollections;
-
-        $collection_metadata = $TainacanCollections->get_metadata( $item->get_collection() );
-        foreach ($collection_metadata as $metadata) {
-
-        }
-    }
-    
 }
 
 global $TainacanItems;
diff --git a/src/classes/Repositories/Metatadas.php b/src/classes/Repositories/Metatadas.php
index c1ccc2a20..8c305d05c 100644
--- a/src/classes/Repositories/Metatadas.php
+++ b/src/classes/Repositories/Metatadas.php
@@ -37,11 +37,23 @@ class Tainacan_Metadatas {
         ],
         'required' => [
             'map' => 'meta',
-            'validation' => ''
+            'validation' => '', // yes or no
+            'default' => 'no'
+        ],
+        'collection_key' => [
+            'map' => 'meta',
+            'validation' => '', // yes or no. it cant be key if its multiple
+            'default' => 'no'
+        ],
+        'multiple' => [
+            'map' => 'meta',
+            'validation' => '', // yes or no. It cant be multiple if its collection_key
+            'default' => 'no'
         ],
         'cardinality' => [
             'map' => 'meta',
-            'validation' => ''
+            'validation' => '',
+            'default' => 1
         ],
         'privacy' => [
             'map' => 'meta',
@@ -114,7 +126,7 @@ class Tainacan_Metadatas {
         // First iterate through the native post properties
         $map = $this->map;
         foreach ($map as $prop => $mapped) {
-            if ($mapped['map'] != 'meta') {
+            if ($mapped['map'] != 'meta' && $mapped['map'] != 'meta_multi') {
                 $metadata->WP_Post->{$mapped['map']} = $metadata->get_mapped_property($prop);
             }
         }
@@ -137,8 +149,9 @@ class Tainacan_Metadatas {
                         add_post_meta($id, $prop, $value);
             }
         }
-
-        return $id;
+        
+        // return a brand new object
+        return new Tainacan_Metadata($metadata->WP_Post);
     }
 
     /**
diff --git a/src/classes/Repositories/Taxonomies.php b/src/classes/Repositories/Taxonomies.php
index 152f652bb..cf32df697 100644
--- a/src/classes/Repositories/Taxonomies.php
+++ b/src/classes/Repositories/Taxonomies.php
@@ -112,7 +112,7 @@ class Tainacan_Taxonomies {
         // First iterate through the native post properties
         $map = $this->map;
         foreach ($map as $prop => $mapped) {
-            if ($mapped['map'] != 'meta') {
+            if ($mapped['map'] != 'meta' && $mapped['map'] != 'meta_multi') {
                 $taxonomy->WP_Post->{$mapped['map']} = $taxonomy->get_mapped_property($prop);
             }
         }
@@ -138,7 +138,8 @@ class Tainacan_Taxonomies {
         
         $taxonomy->register_taxonomy();
         
-        return $id;
+        // return a brand new object
+        return new Tainacan_Taxonomy($taxonomy->WP_Post);
     }
 
     function registerTainacanTaxonomy( $taxonomy_name ){
diff --git a/src/classes/Traits/EntityCollectionRelation.php b/src/classes/Traits/EntityCollectionRelation.php
index 4d98af5bc..227a5664c 100644
--- a/src/classes/Traits/EntityCollectionRelation.php
+++ b/src/classes/Traits/EntityCollectionRelation.php
@@ -24,8 +24,9 @@ trait EntityCollectionRelation {
     }
     
     function set_collection_id($value) {
-        return $this->set_mapped_property('collection_id', $value);
         $this->collection = null;
+        return $this->set_mapped_property('collection_id', $value);
+        
     }
     
     function set_collection(TainacanCollection $collection) {
diff --git a/src/test-tainacan.php b/src/test-tainacan.php
index 80e725323..c4799690b 100644
--- a/src/test-tainacan.php
+++ b/src/test-tainacan.php
@@ -14,12 +14,14 @@ include('classes/Repositories/Items.php');
 include('classes/Repositories/Metatadas.php');
 include('classes/Repositories/Taxonomies.php');
 include('classes/Repositories/Terms.php');
+include('classes/Repositories/ItemMetadata.php');
 include('classes/Entity.php');
 include('classes/Entities/Collection.php');
 include('classes/Entities/Item.php');
 include('classes/Entities/Metadata.php');
 include('classes/Entities/Taxonomy.php');
 include('classes/Entities/Term.php');
+include('classes/Entities/Item_Metadata_Entity.php');
 include('classes/FieldTypes/FieldType.php');
 include('classes/FieldTypes/TextFieldType.php');
 
diff --git a/tests/test-item-metadata.php b/tests/test-item-metadata.php
new file mode 100644
index 000000000..59672e4a2
--- /dev/null
+++ b/tests/test-item-metadata.php
@@ -0,0 +1,151 @@
+<?php
+/**
+ * Class TestCollections
+ *
+ * @package Test_Tainacan
+ */
+
+/**
+ * Sample test case.
+ */
+class TestItemMetadata extends WP_UnitTestCase {
+
+    /**
+     * Teste da insercao de um metadado simples sem o tipo
+     */
+    function test_add() {
+        
+        global $TainacanCollections, $Tainacan_Metadatas, $Tainacan_Item_Metadata;
+
+        $collection = new TainacanCollection();
+        $metadata = new Tainacan_Metadata();
+
+        $collection->set_name('teste');
+        $collection = $TainacanCollections->insert($collection);
+
+        //setando os valores na classe do metadado
+        $metadata->set_name('metadado');
+        $metadata->set_description('descricao');
+        $metadata->set_collection( $collection );
+
+        //inserindo o metadado
+        $metadata = $Tainacan_Metadatas->insert($metadata);
+
+        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata->get_id());
+        
+        $i = new TainacanItem();
+        
+        $i->set_title('item teste');
+        $i->set_description('adasdasdsa');
+        $i->set_collection($collection);
+        
+        global $TainacanItems;
+        $item = $TainacanItems->insert($i);
+        
+        $item = $TainacanItems->get_item_by_id($item->get_id());
+
+        $item_metadata = new Tainacan_Item_Metadata_Entity($item, $metadata);
+        
+        $item_metadata->set_value('teste_value');
+        
+        $item_metadata = $Tainacan_Item_Metadata->insert($item_metadata);
+        
+        $this->assertEquals('teste_value', $item_metadata->get_value());
+        
+        
+
+    }
+
+    /**
+     * Teste da insercao de um metadado simples com o tipo
+     */
+    function teste_required(){
+        global $TainacanCollections, $Tainacan_Metadatas, $Tainacan_Item_Metadata;
+
+        $collection = new TainacanCollection();
+        $metadata = new Tainacan_Metadata();
+
+        $collection->set_name('teste');
+        $collection = $TainacanCollections->insert($collection);
+
+        //setando os valores na classe do metadado
+        $metadata->set_name('metadado');
+        $metadata->set_description('descricao');
+        $metadata->set_collection( $collection );
+        $metadata->set_required( 'yes' );
+
+        //inserindo o metadado
+        $metadata = $Tainacan_Metadatas->insert($metadata);
+
+        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata->get_id());
+        
+        $i = new TainacanItem();
+        
+        $i->set_title('item teste');
+        $i->set_description('adasdasdsa');
+        $i->set_collection($collection);
+        
+        global $TainacanItems;
+        $item = $TainacanItems->insert($i);
+        
+        $item = $TainacanItems->get_item_by_id($item->get_id());
+
+        $item_metadata = new Tainacan_Item_Metadata_Entity($item, $metadata);
+        
+        // false because its required
+        $this->assertFalse($item_metadata->validate());
+        
+        $item_metadata->set_value('teste_value');
+        
+        $this->assertTrue($item_metadata->validate());
+        
+        $item_metadata = $Tainacan_Item_Metadata->insert($item_metadata);
+        
+        $this->assertEquals('teste_value', $item_metadata->get_value());
+    }
+    
+    function teste_collection_key(){
+        global $TainacanCollections, $Tainacan_Metadatas, $Tainacan_Item_Metadata;
+
+        $collection = new TainacanCollection();
+        $metadata = new Tainacan_Metadata();
+
+        $collection->set_name('teste');
+        $collection = $TainacanCollections->insert($collection);
+
+        //setando os valores na classe do metadado
+        $metadata->set_name('metadado');
+        $metadata->set_description('descricao');
+        $metadata->set_collection( $collection );
+        $metadata->set_collection_key( 'yes' );
+
+        //inserindo o metadado
+        $metadata = $Tainacan_Metadatas->insert($metadata);
+
+        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata->get_id());
+        
+        $i = new TainacanItem();
+        
+        $i->set_title('item teste');
+        $i->set_description('adasdasdsa');
+        $i->set_collection($collection);
+        
+        global $TainacanItems;
+        $item = $TainacanItems->insert($i);
+        
+        $item = $TainacanItems->get_item_by_id($item->get_id());
+
+        
+        
+        $value = 'teste_val';
+        
+        $item_metadata = new Tainacan_Item_Metadata_Entity($item, $metadata);
+        $item_metadata->set_value($value);
+        $this->assertTrue($item_metadata->validate());
+        $item_metadata = $Tainacan_Item_Metadata->insert($item_metadata);
+
+        $n_item_metadata = new Tainacan_Item_Metadata_Entity($item, $metadata);
+        $n_item_metadata->set_value($value);
+        $this->assertFalse($n_item_metadata->validate());
+    }
+}
\ No newline at end of file
diff --git a/tests/test-items.php b/tests/test-items.php
new file mode 100644
index 000000000..c0a129b62
--- /dev/null
+++ b/tests/test-items.php
@@ -0,0 +1,143 @@
+<?php
+/**
+ * Class TestCollections
+ *
+ * @package Test_Tainacan
+ */
+
+/**
+ * Sample test case.
+ */
+class TestItems extends WP_UnitTestCase {
+
+    
+    function teste_query(){
+        global $TainacanCollections, $Tainacan_Metadatas, $Tainacan_Item_Metadata;
+
+        $collection = new TainacanCollection();
+        $collection2 = new TainacanCollection();
+        
+        $collection->set_name('teste');
+        $collection = $TainacanCollections->insert($collection);
+        $collection2->set_name('teste2');
+        $collection2 = $TainacanCollections->insert($collection2);
+        
+        $metadata = new Tainacan_Metadata();
+        $metadata2 = new Tainacan_Metadata();
+        $metadata3 = new Tainacan_Metadata();
+        
+        $metadata->set_name('metadado');
+        $metadata->set_collection( $collection );
+        $metadata = $Tainacan_Metadatas->insert($metadata);
+        $metadata2->set_name('metadado2');
+        $metadata2->set_collection( $collection2 );
+        $metadata2 = $Tainacan_Metadatas->insert($metadata2);
+        $metadata3->set_name('metadado3');
+        $metadata3->set_collection( $collection2 );
+        $metadata3 = $Tainacan_Metadatas->insert($metadata3);
+
+        global $TainacanItems;
+        $i = new TainacanItem();
+        $i->set_title('orange');
+        $i->set_collection($collection);
+        $i->add_metadata($metadata, 'value_1');
+        $item = $TainacanItems->insert($i);
+        
+        $item = $TainacanItems->get_item_by_id($item->get_id());
+        $meta_test = $item->get_metadata();
+        
+        $this->assertTrue( isset($meta_test[$metadata->get_id()]) );
+        $this->assertTrue( $meta_test[$metadata->get_id()] instanceof Tainacan_Item_Metadata_Entity );
+        $this->assertEquals( $meta_test[$metadata->get_id()]->get_value(), 'value_1');
+        
+        $i = new TainacanItem();
+        $i->set_title('apple');
+        $i->set_collection($collection2);
+        $i->add_metadata($metadata2, 'value_2');
+        $i->add_metadata($metadata3, 'value_2');
+        $item = $TainacanItems->insert($i);
+        
+        $i = new TainacanItem();
+        $i->set_title('lemon');
+        $i->set_collection($collection2);
+        $i->add_metadata($metadata2, 'value_2');
+        $i->add_metadata($metadata2, 'value_3'); // if we set twice, value is overridden
+        $i->add_metadata($metadata3, 'value_3');
+        $item = $TainacanItems->insert($i);
+        
+        $i = new TainacanItem();
+        $i->set_title('pinapple');
+        $i->set_collection($collection2);
+        $i->add_metadata($metadata2, 'value_3');
+        $i->add_metadata($metadata3, 'value_6');
+        $item = $TainacanItems->insert($i);
+        
+        // should return all 4 items
+        $test_query = $TainacanItems->query([]);
+        $this->assertEquals(4, sizeof($test_query));
+        
+        // should also return all 4 items
+        $test_query = $TainacanItems->query(['collections' => [$collection, $collection2]]);
+        $this->assertEquals(4, sizeof($test_query));
+        
+        // should return only the first item
+        $test_query = $TainacanItems->query(['collections' => $collection]);
+        $this->assertEquals(1, sizeof($test_query));
+        $this->assertEquals('orange', $test_query[0]->get_title());
+        $test_query = $TainacanItems->query(['title' => 'orange']);
+        $this->assertEquals(1, sizeof($test_query));
+        $this->assertEquals('orange', $test_query[0]->get_title());
+        
+        // should return the other 3 items
+        $test_query = $TainacanItems->query(['collections' => $collection2]);
+        $this->assertEquals(3, sizeof($test_query));
+        
+        $test_query = $TainacanItems->query(['title' => 'apple']);
+        $this->assertEquals(1, sizeof($test_query));
+        $this->assertEquals('apple', $test_query[0]->get_title());
+        $apple_meta = $test_query[0]->get_metadata();
+        $this->assertEquals(2, sizeof($apple_meta));
+        $apple_meta_values = [];
+        foreach ($apple_meta as $am) {
+            $this->assertEquals('value_2', $am->get_value());
+        }
+        
+        // should return 1 item
+        $test_query = $TainacanItems->query([
+            'collections' => $collection2,
+            'metadata' => [
+                [
+                    'key' => $metadata2->get_id(),
+                    'value' => 'value_2'
+                ]
+            ]
+        ]);
+        $this->assertEquals(1, sizeof($test_query));
+        
+        // should return 2 items
+        $test_query = $TainacanItems->query([
+            'collections' => $collection2,
+            'metadata' => [
+                [
+                    'key' => $metadata2->get_id(),
+                    'value' => 'value_3'
+                ]
+            ]
+        ]);
+        $this->assertEquals(2, sizeof($test_query));
+        
+        // should return 2 item
+        $test_query = $TainacanItems->query([
+            'collections' => $collection2,
+            'metadata' => [
+                [
+                    'key' => $metadata3->get_id(),
+                    'value' => 'value_2',
+                    'compare' => '>'
+                ]
+            ]
+        ]);
+        $this->assertEquals(2, sizeof($test_query));
+
+    }
+}
\ No newline at end of file
diff --git a/tests/test-metadata.php b/tests/test-metadata.php
index 3106c8588..a25b36bd2 100644
--- a/tests/test-metadata.php
+++ b/tests/test-metadata.php
@@ -20,21 +20,21 @@ class TestMetadata extends WP_UnitTestCase {
         $metadata = new Tainacan_Metadata();
 
         $collection->set_name('teste');
-        $id = $TainacanCollections->insert($collection);
+        $collection = $TainacanCollections->insert($collection);
 
         //setando os valores na classe do metadado
         $metadata->set_name('metadado');
         $metadata->set_description('descricao');
-        $metadata->set_collection_id( $id );
+        $metadata->set_collection( $collection );
 
         //inserindo o metadado
-        $metadata_id = $Tainacan_Metadatas->insert($metadata);
+        $metadata = $Tainacan_Metadatas->insert($metadata);
 
-        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata_id);
+        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata->get_id());
 
         $this->assertEquals($test->get_name(), 'metadado');
         $this->assertEquals($test->get_description(), 'descricao');
-        $this->assertEquals($test->get_collection()->get_id(), $id);
+        $this->assertEquals($test->get_collection_id(), $collection->get_id());
 
     }
 
@@ -49,20 +49,21 @@ class TestMetadata extends WP_UnitTestCase {
         $type = new Tainacan_Text_Field_Type();
 
         $collection->set_name('teste');
-        $id = $TainacanCollections->insert($collection);
+        $collection = $TainacanCollections->insert($collection);
 
         //setando os valores na classe do metadado
         $metadata->set_name('metadado');
-        $metadata->set_collection_id( $id );
+        $metadata->set_collection_id( $collection->get_id() );
         $metadata->set_type( $type );
 
-        //inserindo o metadado
-        $metadata_id = $Tainacan_Metadatas->insert($metadata);
 
-        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata_id);
+        //inserindo o metadado
+        $metadata = $Tainacan_Metadatas->insert($metadata);
+
+        $test = $Tainacan_Metadatas->get_metadata_by_id($metadata->get_id());
 
         $this->assertEquals($test->get_name(), 'metadado');
-        $this->assertEquals($test->get_collection()->get_id(), $id);
+        $this->assertEquals($test->get_collection_id(), $collection->get_id());
         $this->assertEquals($test->get_type('name'), 'Tainacan_Text_Field_Type');
         $this->assertEquals($test->get_type(), $type);
     }
diff --git a/tests/test-sample.php b/tests/test-sample.php
index 5dcbce3bf..d6817b4f8 100644
--- a/tests/test-sample.php
+++ b/tests/test-sample.php
@@ -22,11 +22,11 @@ class TestCollections extends WP_UnitTestCase {
         $x->set_itens_per_page(23);
         
         global $TainacanCollections;
-        $id = $TainacanCollections->insert($x);
+        $col = $TainacanCollections->insert($x);
         
         //
         
-        $test = $TainacanCollections->get_collection_by_id($id);
+        $test = $TainacanCollections->get_collection_by_id($col->get_id());
         
         
         $this->assertEquals($test->get_name(), 'teste');
@@ -46,9 +46,9 @@ class TestCollections extends WP_UnitTestCase {
         $x->set_itens_per_page(23);
         
         global $TainacanCollections;
-        $cid = $TainacanCollections->insert($x);
+        $col = $TainacanCollections->insert($x);
         
-        $collection = $TainacanCollections->get_collection_by_id($cid);
+        $collection = $TainacanCollections->get_collection_by_id($col->get_id());
         
         
         
@@ -59,13 +59,13 @@ class TestCollections extends WP_UnitTestCase {
         $i->set_collection($collection);
         
         global $TainacanItems;
-        $id = $TainacanItems->insert($i);
+        $item = $TainacanItems->insert($i);
         
-        $item = $TainacanItems->get_item_by_id($id);
+        $item = $TainacanItems->get_item_by_id($item->get_id());
         
         $this->assertEquals($item->get_title(), 'item teste');
         $this->assertEquals($item->get_description(), 'adasdasdsa');
-        $this->assertEquals($item->get_collection_id(), $cid);
+        $this->assertEquals($item->get_collection_id(), $collection->get_id());
         
     }
 }
diff --git a/tests/test-taxonomies.php b/tests/test-taxonomies.php
index d3e976796..e636dcc42 100644
--- a/tests/test-taxonomies.php
+++ b/tests/test-taxonomies.php
@@ -25,10 +25,10 @@ class TestTaxonomies extends WP_UnitTestCase {
         $taxonomy->set_allow_insert(true);
 
         //inserindo
-        $taxonomy_id = $Tainacan_Taxonomies->insert($taxonomy);
+        $taxonomy = $Tainacan_Taxonomies->insert($taxonomy);
 
         //retorna a taxonomia
-        $test = $Tainacan_Taxonomies->get_taxonomy_by_id($taxonomy_id);
+        $test = $Tainacan_Taxonomies->get_taxonomy_by_id($taxonomy->get_id());
 
         $this->assertEquals( $test->get_name(), 'genero' );
         $this->assertEquals( $test->get_description(), 'tipos de musica' );
@@ -45,10 +45,10 @@ class TestTaxonomies extends WP_UnitTestCase {
         $taxonomy->set_name('genero');
 
         //insere a taxonomia
-        $taxonomy_id = $Tainacan_Taxonomies->insert($taxonomy);
+        $taxonomy = $Tainacan_Taxonomies->insert($taxonomy);
 
         //retorna a taxonomia
-        $taxonomy_test = $Tainacan_Taxonomies->get_taxonomy_by_id($taxonomy_id);
+        $taxonomy_test = $Tainacan_Taxonomies->get_taxonomy_by_id($taxonomy->get_id());
 
         //insere um termo na taxonomia
         $term->set_taxonomy( $taxonomy_test->get_db_identifier() );