Date Picker
===

Select a range of dates or single dates

## Usage

```jsx
<DatePicker query={ query } path={ path } key={ JSON.stringify( query ) } />
```

### Props

Required props are marked with `*`.

Name | Type | Default | Description
--- | --- | --- | ---
`query`* | `object` | none | The query string represented in object form
`path`* | `string` | none | `path` parameter supplied by React-Router
`key`| `*` | none |  Force a recalculation or reset of internal state when this key changes. Useful for a url change, for instance

## URL as the source of truth

The Date Picker reads parameters from the URL querystring and updates them by creating a link to reflect newly selected parameters, which is rendered as the "Update" button.
 
 URL Parameter | Default | Possible Values
 --- | --- | ---
 `period` | `today` | `today`, `yesterday`, `week`, `last_week`, `month`, `last_month`, `quarter`, `last_quarter`, `year`, `last_year`, `custom`
 `compare` | `previous_period` | `previous_period`, `previous_year`
 `start` | none | start date for custom periods `2018-04-15`. [ISO 8601 format](https://en.wikipedia.org/wiki/ISO_8601)
 `end` | none | end date for custom periods `2018-04-15`. [ISO 8601 format](https://en.wikipedia.org/wiki/ISO_8601)