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Data Binding Basics

The main function of the Grid is to display model data.

The appropriate type of data binding depends on the scenario and features of your project. The Grid enables you to bind it to an array or GridDataResult objects by setting the data property of the <kendo-grid> tag.

When you bind the Grid to data, note the following specifics:

  • When paging is disabled, bind the data directly as an Array object.
  • When paging or virtual scrolling is enabled, use the GridDataResult option. It enables you to set the total number of records in a data length that is different from the currently provided one.
  • When the data is received from an asynchronous source, pipe it through the async pipe.
  • When the data contains dates, they need to be instances of the JavaScript Date object. This ensures that dates are handled correctly during formatting, sorting, filtering, and editing.

You can use the built-in loading panel to indicate an ongoing operation to the user. To toggle the loading panel, set the loading attribute to true.

import { Component } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { CategoriesService } from './northwind.service';

import { State } from '@progress/kendo-data-query';

import {
    GridDataResult,
    DataStateChangeEvent
} from '@progress/kendo-angular-grid';

@Component({
    selector: 'my-app',
    template: `
       <kendo-grid
          [data]="view | async"
          [loading]="view.loading"
          [pageSize]="state.take"
          [skip]="state.skip"
          [sort]="state.sort"
          [sortable]="true"
          [pageable]="true"
          [scrollable]="'none'"
          (dataStateChange)="dataStateChange($event)"
        >
        <kendo-grid-column field="CategoryID" width="130"></kendo-grid-column>
        <kendo-grid-column field="CategoryName" width="200"></kendo-grid-column>
        <kendo-grid-column field="Description" [sortable]="false">
        </kendo-grid-column>
      </kendo-grid>
    `
})
export class AppComponent {
    public view: Observable<GridDataResult>;
    public state: State = {
        skip: 0,
        take: 5
    };

    constructor(private service: CategoriesService) {
        this.view = service;
        this.service.query(this.state);
    }

    public dataStateChange(state: DataStateChangeEvent): void {
        this.state = state;
        this.service.query(state);
    }
}

import { NgModule, enableProdMode } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { HttpClientModule } from '@angular/common/http';

import { GridModule } from '@progress/kendo-angular-grid';

import { AppComponent } from './app.component';
import { CategoriesService } from './northwind.service';

enableProdMode();

@NgModule({
  imports: [ BrowserModule, BrowserAnimationsModule, GridModule, HttpClientModule ],
  declarations: [ AppComponent ],
  providers: [ CategoriesService ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app.module';

enableProdMode();

const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule);

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { GridDataResult } from '@progress/kendo-angular-grid';
import { toODataString } from '@progress/kendo-data-query';
import { Observable } from 'rxjs/Observable';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { map } from 'rxjs/operators/map';
import { tap } from 'rxjs/operators/tap';

export abstract class NorthwindService extends BehaviorSubject<GridDataResult> {
    public loading: boolean;

    private BASE_URL = 'https://odatasampleservices.azurewebsites.net/V4/Northwind/Northwind.svc/';

    constructor(
        private http: HttpClient,
        protected tableName: string
    ) {
        super(null);
    }

    public query(state: any): void {
        this.fetch(this.tableName, state)
            .subscribe(x => super.next(x));
    }

    protected fetch(tableName: string, state: any): Observable<GridDataResult> {
        const queryStr = `${toODataString(state)}&$count=true`;
        this.loading = true;

        return this.http
            .get(`${this.BASE_URL}${tableName}?${queryStr}`)
            .pipe(
                map(response => (<GridDataResult>{
                    data: response['value'],
                    total: parseInt(response['@odata.count'], 10)
                })),
                tap(() => this.loading = false)
            );
    }
}

@Injectable()
export class ProductsService extends NorthwindService {
    constructor(http: HttpClient) { super(http, 'Products'); }

    public queryForCategory({ CategoryID }: { CategoryID: number }, state?: any): void {
        this.query(Object.assign({}, state, {
            filter: {
                filters: [{
                    field: 'CategoryID', operator: 'eq', value: CategoryID
                }],
                logic: 'and'
            }
        }));
    }

    public queryForProductName(ProductName: string, state?: any): void {
        this.query(Object.assign({}, state, {
            filter: {
                filters: [{
                    field: 'ProductName', operator: 'contains', value: ProductName
                }],
                logic: 'and'
            }
        }));
    }

}

@Injectable()
export class CategoriesService extends NorthwindService {
    constructor(http: HttpClient) { super(http, 'Categories'); }

    queryAll(st?: any): Observable<GridDataResult> {
        const state = Object.assign({}, st);
        delete state.skip;
        delete state.take;

        return this.fetch(this.tableName, state);
    }
}
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