Custom Sources

DevExtreme provides the CustomStore component, a flexible instrument that allows you to configure data access manually, for consuming data from any source. The following extensions for ASP.NET and PHP servers simplify the task of configuring the CustomStore and implement server-side data processing as well:

You need to configure the CustomStore in detail for accessing a server built on another technology. Data in this situation can be processed on the client or server. In the former case, switch the CustomStore to the raw mode and load all data from the server in the load function as shown in the next example.

jQuery
JavaScript
$(function() {
    $("#lookupContainer").dxLookup({
        dataSource: new DevExpress.data.DataSource({
            store: new DevExpress.data.CustomStore({
                loadMode: "raw",   
                load: function () {
                    return $.getJSON('https://mydomain.com/MyDataService');
                }
            })
        })
    });
});
Angular
TypeScript
HTML
import { ..., Inject } from '@angular/core';
import { Http, HttpModule } from '@angular/http';
import DataSource from 'devextreme/data/data_source';
import { DxLookupModule } from 'devextreme-angular';
import CustomStore from 'devextreme/data/custom_store';
import 'rxjs/add/operator/toPromise';
// ...
export class AppComponent {
    lookupDataSource: any = {};
    constructor(@Inject(Http) http: Http) {
        this.lookupData = new DataSource({
            store: new CustomStore({
                loadMode: "raw",   
                load: function () {
                    return http.get('https://mydomain.com/MyDataService')
                                .toPromise()
                                .then(response => {
                                    return response.json();
                                });
                }
            })
        })
    }
}
@NgModule({
    imports: [
        // ...
        DxLookupModule
    ],
    // ...
})
<dx-lookup
    dataSource="lookupData">
</dx-lookup>
NOTE
We advise against using this mode with large amounts of data because all data is loaded at once.

In the latter case, use the CustomStore's load function to send data processing settings to the server. These settings are passed as a parameter to the load function and depend on the operations (paging, filtering, sorting, etc.) that you have enabled in the DataSource. The following settings are relevant for the Lookup:

  • take: Number
    Restricts the number of top-level data objects to return.

  • skip: Number
    Skips some data objects from the start of the result set. skip and take are present if paginate is true and pageSize is set in the DataSource.

  • sort: Array
    Defines sorting parameters. Present if the DataSource's sort option is set. Multiple parameters apply to the data in sequence to implement multi-level sorting. Contains objects of the following structure:

    { selector: "field", desc: true/false }    
  • filter: Array
    Defines filtering parameters. Present if the DataSource's filter option is set. Possible variants:

    • Binary filter

      [ "field", "=", 3 ]
    • Unary filter

       [ "!", [ "field", "=", 3 ] ]
    • Complex filter

      [
          [ "field", "=", 10 ],
          "and",
          [
              [ "otherField", "<", 3 ],
              "or",
              [ "otherField", ">", 11 ]
          ]
      ]

    See the Filtering topic for more details.

  • searchExpr, searchOperation and searchValue: Strings
    Another way to define a filter restricted to one criterion. Present if corresponding options are set in the DataSource.

  • group: Array
    Defines grouping levels to be applied to the data. Present if the DataSource's group option is set. Contains objects of the following structure:

    { selector: "field", desc: true/false }

    See the Grouping topic for more details.

After receiving these settings, the server should apply them to data and send back an object of the following structure:

{
    data: [{
        key: "Group 1",
        items: [ ... ] // result data objects
    },
    ...
    ]
}

If the group setting is absent, the object structure is different:

{
    data: [ ... ] // result data objects
}

If you specify the Lookup's value beforehand, the CustomStore must implement the byKey operation as well. Here is a generalized configuration of the CustomStore for the Lookup widget.

jQuery
JavaScript
$(function() {
    $("#lookupContainer").dxLookup({
        dataSource: new DevExpress.data.DataSource({
            load: function (loadOptions) {
                var d = $.Deferred();
                $.getJSON("http://mydomain.com/MyDataService", {
                    skip: loadOptions.skip,
                    take: loadOptions.take,
                    sort: loadOptions.sort ? JSON.stringify(loadOptions.sort) : "",
                    filter: loadOptions.filter ? JSON.stringify(loadOptions.filter) : "",
                    searchExpr: loadOptions.searchExpr ? JSON.stringify(loadOptions.searchExpr) : "",
                    searchOperation: loadOptions.searchOperation,
                    searchValue: loadOptions.searchValue,
                    group: loadOptions.group ? JSON.stringify(loadOptions.group) : ""
                }).done(function(result) {
                    // Here, you can perform operations unsupported by the server
                    d.resolve(result.data);
                });
                return d.promise();
            },
            byKey: function (key) {
                var d = new $.Deferred();
                $.get('https://mydomain.com/MyDataService?id=' + key)
                    .done(function (result) {
                        d.resolve(result);
                    });
                return d.promise();
            }
        })
    });
});
Angular
TypeScript
HTML
import { ..., Inject } from '@angular/core';
import { Http, HttpModule, URLSearchParams } from '@angular/http';
import { DxLookupModule } from 'devextreme-angular';
import DataSource from 'devextreme/data/data_source';
import CustomStore from 'devextreme/data/custom_store';
import 'rxjs/add/operator/toPromise';
// ...
export class AppComponent {
    lookupData: any = {};
    constructor(@Inject(Http) http: Http) {
        this.lookupData = new DataSource({
            store: new CustomStore({
                load: function (loadOptions) {
                    let params: URLSearchParams = new URLSearchParams();
                    params.set("skip", loadOptions.skip);
                    params.set("take", loadOptions.take);
                    params.set("sort", loadOptions.sort ? JSON.stringify(loadOptions.sort) : "");
                    params.set("searchExpr", loadOptions.searchExpr ? JSON.stringify(loadOptions.searchExpr) : "");
                    params.set("searchOperation", loadOptions.searchOperation);
                    params.set("searchValue", loadOptions.searchValue);
                    params.set("filter", loadOptions.filter ? JSON.stringify(loadOptions.filter) : "");
                    params.set("group", loadOptions.group ? JSON.stringify(loadOptions.group) : "");
                    return http.get('http://mydomain.com/MyDataService', {
                                    search: params
                                })
                                .toPromise()
                                .then(response => {
                                    var json = response.json();
                                    // You can process the received data here
                                    return {
                                        data: json.data
                                    }
                                });
                },
                byKey: function (key) {
                    return http.get('https://mydomain.com/MyDataService?id=' + key)
                                .toPromise()
                                .then(response => {
                                    var json = response.json();
                                    return {
                                        data: json.data
                                    };
                                });
                }
            })
        });
    }
}
@NgModule({
     imports: [
         // ...
         DxLookupModule,
         HttpModule 
     ],
     // ...
 })
<dx-lookup
    [dataSource]="lookupData">
</dx-lookup>
See Also