validation - 在 Angular2 的自定义验证器中注入(inject)服务

Question

我尝试在自定义验证器中使用服务来检查用户名是否已存在。

import {Component} from 'angular2/core';
import {
    Control,
    ControlGroup,
    FormBuilder
} from "angular2/common";
import {CharacterService} from "./character-service";

@Component({
    selector: 'register-character-form',
    template: `
        <h2 class="ui header">A new adventurer is coming...</h2>
        <form (ngSubmit)="register()" [ngFormModel]="characterForm" class="ui form">
            <div class="field">
                <label>Nom</label>
                <input ngControl="name">
            </div>
            <button type="submit" class="ui button">Enter in the adventure</button>
        </form>
    `,
    providers: [CharacterService]
})
export class RegisterCharacterFormCmp {
    characterForm: ControlGroup;
    name: Control;

    constructor(private _characterService: CharacterService, fb: FormBuilder) {
        this.name = fb.control('', this.characterNameValidator);

        this.characterForm = fb.group({
            name: this.name
        });
    }

    register(): void {
        //TODO: To implement
    }

    // Not works, this binds the control
    characterNameValidator(control: Control) {
        return this._characterService.isCharacterNameAlreadyExists(control.value) ? {nameCharacterAlreadyExistsError: true} : null;
    }
}

这是行不通的。在 characterNameValidator 中，'this' 引用控件而不是我的类。服务未定义。我如何在验证器中使用我的服务？

更广泛地说，我如何在自定义验证器中传递参数？

Answer 1

您需要在验证中控制this 的含义。您可以使用 bind 来做到这一点

this.name = fb.control('', this.characterNameValidator.bind(this));

然后其他一切都应该按预期工作。