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<h1>DataView documentation</h1>
<h2 id="Contents">Contents</h2><ul>  <li><a href="#Overview">Overview</a></li>  <li><a href="#Example">Example</a></li>  <li><a href="#Construction">Construction</a></li>  <li><a href="#Getting_Data">Getting Data</a></li>  <li><a href="#Subscriptions">Subscriptions</a></li>  <li><a href="#Data_Policy">Data Policy</a></li></ul>

<h2 id="Overview">Overview</h2>
<p>  A DataView offers a filtered and/or formatted view on a  <a href="dataset.html">DataSet</a>.  One can subscribe on changes in a DataView, and easily get filtered or  formatted data without having to specify filters and field types all  the time.</p>
<h2 id="Example">Example</h2>
<p>  The following example shows how to use a DataView.</p>
<pre class="prettyprint lang-js">// create a DataSetvar data = new vis.DataSet();data.add([  {id: 1, text: 'item 1', date: new Date(2013, 6, 20), group: 1, first: true},  {id: 2, text: 'item 2', date: '2013-06-23', group: 2},  {id: 3, text: 'item 3', date: '2013-06-25', group: 2},  {id: 4, text: 'item 4'}]);
// create a DataView// the view will only contain items having a property group with value 1,// and will only output fields id, text, and date.var view = new vis.DataView(data, {  filter: function (item) {    return (item.group == 1);  },  fields: ['id', 'text', 'date']});
// subscribe to any change in the DataViewview.subscribe('*', function (event, params, senderId) {  console.log('event', event, params);});
// update an item in the data setdata.update({id: 2, group: 1});
// get all ids in the viewvar ids = view.getIds();console.log('ids', ids); // will output [1, 2]
// get all items in the viewvar items = view.get();</pre>
<h2 id="Construction">Construction</h2>

<p>  A DataView can be constructed as:</p>
<pre class="prettyprint lang-js">var data = new vis.DataView(dataset, options)</pre>
<p>  where:</p>
<ul>  <li>    <code>dataset</code> is a DataSet or DataView.  </li>  <li>    <code>options</code> is an object which can    contain the following properties. Note that these properties    are exactly the same as the properties available in methods    <code>DataSet.get</code> and <code>DataView.get</code>.


    <table>      <tr>        <th>Name</th>        <th>Type</th>        <th>Description</th>      </tr>
      <tr>        <td>convert</td>        <td>Object.&lt;String,&nbsp;String&gt;</td>        <td>          An object containing field names as key, and data types as value.          By default, the type of the properties of an item are left          unchanged. When a field type is specified, this field in the          items will be converted to the specified type. This can be used          for example to convert ISO strings containing a date to a          JavaScript Date object, or convert strings to numbers or vice          versa. The available data types are listed in section          <a href="dataset.html#Data_Types">Data Types</a>.        </td>      </tr>
      <tr>        <td>fields</td>        <td>String[&nbsp;]</td>        <td>          An array with field names.          By default, all properties of the items are emitted.          When <code>fields</code> is defined, only the properties          whose name is specified in <code>fields</code> will be included          in the returned items.        </td>      </tr>
      <tr>        <td>filter</td>        <td>function</td>        <td>Items can be filtered on specific properties by providing a filter          function. A filter function is executed for each of the items in the          DataSet, and is called with the item as parameter. The function must          return a boolean. All items for which the filter function returns          true will be emitted.          See also section <a href="dataset.html#Data_Filtering">Data Filtering</a>.</td>      </tr>
    </table>  </li></ul>
<h2 id="Getting_Data">Getting Data</h2>
<p>  Data of the DataView can be retrieved using the method <code>get</code>.</p>
<pre class="prettyprint lang-js">var items = view.get();</pre>
<p>  Data of a DataView can be filtered and formatted again, in exactly the  same way as in a DataSet. See sections  <a href="dataset.html#Data_Filtering">Data Filtering</a> and  <a href="dataset.html#Data_Formatting">Data Formatting</a> for more  information.</p>
<pre class="prettyprint lang-js">var items = view.get({  fields: ['id', 'score'],  filter: function (item) {    return (item.score > 50);  }});</pre>


<h2 id="Subscriptions">Subscriptions</h2><p>  One can subscribe on changes in the DataView. Subscription works exactly  the same as for DataSets. See the documentation on  <a href="dataset.html#Subscriptions">subscriptions in a DataSet</a>  for more information.</p>
<pre class="prettyprint lang-js">// create a DataSet and a view on the data setvar data = new vis.DataSet();var view = new vis.DataView({  filter: function (item) {    return (item.group == 2);  }});
// subscribe to any change in the DataViewview.subscribe('*', function (event, params, senderId) {  console.log('event:', event, 'params:', params, 'senderId:', senderId);});
// add, update, and remove data in the DataSet...</pre>


<h2 id="Data_Policy">Data Policy</h2><p>  All code and data is processed and rendered in the browser.  No data is sent to any server.</p>
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