在Angular2的自定义验证器中注入服务
问题描述:
我尝试在自定义验证程序中使用服务来检查用户名是否已经存在.
I try to use a service in a custom validator to check if a username already exists.
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;
}
}
它不起作用.在characterNameValidator中,"this"引用控件而不是我的类.服务未定义.如何在验证器中使用我的服务?
It doesn't work. In the characterNameValidator, 'this' references the control and not my class. The service is undefined. How can I use my service in the validator ?
更全面地说,如何在自定义验证器中传递参数?
More globally, how can I pass arguments in a custom validator ?
答
您需要控制this
在验证中的含义.您可以使用 bind
You need to control what this
means in your validation. You can do so with bind
this.name = fb.control('', this.characterNameValidator.bind(this));
其他所有操作都应按预期进行.
Everything else should work as expected then.