DataSource Overview
The Kendo UI DataSource component plays a central role in all web applications built with Kendo UI for jQuery.
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Getting Started
The DataSource is an abstraction for using local data (arrays of JavaScript objects) or remote data (web services returning JSON, JSONP, oData or XML). It fully supports CRUD (Create, Read, Update, Destroy) data operations and provides both client-side and server-side support for sorting, paging, filtering, grouping, and aggregates.
- To sort the data based on an object, set the data field, by which the data items are sorted, to a property of that object.
- To group the data by an object, set the group by data item field to a property of that object.
- To filter the data based on an object, set the data item field, to which the filter operator is applied, to a property of that object.
The following list includes some of the functionality and features which the DataSource provides. For detailed information on the capabilities of the DataSource, refer to its configuration API, methods, and events, and demos.
- Retrieval of data from a remote endpoint.
- Maintaining the structure and type of the data (
schema). - Processing serialization formats to and from a remote endpoint.
- Synchronization of updates—create, update, and delete to and from a remote endpoint.
- Maintaining an in-memory cache of data, including changes for updating to a remote endpoint.
- Calculating and maintaining aggregates, sorting order, and paging.
- Providing a query mechanism through filter expressions.
Binding to Local Data
To bind the DataSource to local data, assign an array of JavaScript objects to the data configuration property of the DataSource instance.
var movies = [{
title: "Star Wars: A New Hope",
year: 1977
}, {
title: "Star Wars: The Empire Strikes Back",
year: 1980
}, {
title: "Star Wars: Return of the Jedi",
year: 1983
}];
var localDataSource = new kendo.data.DataSource({
data: movies
});
Binding to Remote Data Services
When you bind the DataSource to remote data, the component requires information about the web service URLs, the request type, the response data type, and the structure (schema) of the response if it is more complex than a plain array of objects. You can also provide custom parameters which will be submitted during the data request.
var dataSource = new kendo.data.DataSource({
transport: {
read: {
// The remote service url.
url: "http://api.openweathermap.org/data/2.5/find",
// The request type.
type: "get",
// The data type of the returned result.
dataType: "json",
// The additional custom parameters sent to the remote service.
data: {
lat: 42.42,
lon: 23.20,
cnt: 10
}
}
},
// Describe the result format.
schema: {
// The data to which the DataSource will be bound is in the "list" field of the response.
data: "list"
}
});
Using the Mixed Data Operation Mode
All data operations have to occur either on the server or on the client. While you can still determine that part of the data operations will be held on the server and part on the client, using the DataSource in its mixed data-operation mode leads to undesired side effects. For example, if serverPaging is enabled and serverFiltering is disabled, the DataSource will filter only the data from the current page and the user will see less results than expected. In other scenarios, the DataSource might make more requests than necessary for the data operations to execute.
Widget Binding
Kendo UI widgets support data binding and use the DataSource component as a binding source for both local and remote data.
The following example demonstrates how to create a DataSource inline with the other Kendo UI widget settings.
$("#chart").kendoChart({
title: {
text: "Employee Sales"
},
dataSource: new kendo.data.DataSource({
data: [
{
employee: "Joe Smith",
sales: 2000
},
{
employee: "Jane Smith",
sales: 2250
},
{
employee: "Will Roberts",
sales: 1550
}]
}),
series: [{
type: "line",
field: "sales",
name: "Sales in Units"
}],
categoryAxis: {
field: "employee"
}
});
Shared DataSource
The following example demonstrates how to create a shared DataSource and allow multiple Kendo UI widgets to bind to the same data collection. Using a shared DataSource decreases the data requests, improves the performance, and provides automatic synchronized refreshing of all the bound widgets when the data changes.
var sharedDataSource = new kendo.data.DataSource({
transport: {
read: {
url: "data-service.json",
dataType: "json"
}
}
});
// Bind two UI widgets to the same DataSource.
$("#chart").kendoChart({
title: {
text: "Employee Sales"
},
dataSource: sharedDataSource,
series: [{
field: "sales",
name: "Sales in Units"
}],
categoryAxis: {
field: "employee"
}
});
$("#grid").kendoGrid({
dataSource: sharedDataSource,
columns: [
{
field: "employee",
title: "Employee"
},
{
field: "sales",
title: "Sales",
template: '#= kendo.toString(sales, "N0") #'
}]
});