获取子组件为字符串 [英] Get component child as string

问题描述

对于类似I18n的组件，如果我的I18n服务什么都没有得到，我想以字符串形式获取组件内容以具有备用值，该值应该是备用值.

For an I18n-like component, I want to get a component content as string to have a fallback value in case my I18n service gets nothing, this value is supposed to be a fallback one.

I18n服务get方法:

public get(key:string,
               defaultValue?:string,
               variables:Variables = {},
               domain?:string):string {

        for (let catalogue of this.catalogues) {
            if (catalogue.getDomains().indexOf(domain) >= 0
                && catalogue.getLocale() == this.locale
                && catalogue.hasKey(key)) {
                return I18n.setVariables(catalogue.get(key, domain, defaultValue).value, variables);
            }
        }
        return defaultValue;
    }

I18nComponent:

I18nComponent:

@Component({
    selector: "i18n",
    template: "{{text}}",
})
export class I18nComponent implements OnInit {

    constructor(private i18n:I18n) {
    }

    @ContentChild() content:string; //Here, I want to store actual value as fallback one.

    @Input('key') key:string;

    @Input('domain') domain:string;

    @Input('variables')
    variables:Variables = [];

    @Input("plural")
    plural:number;

    text:string;

    ngOnInit():any {
        console.log(this.content); //Here I get 'undefined'
        if (this.plural !== undefined && this.plural != null) {
            this.text = this.i18n.get(this.key, this.content, this.variables, this.domain);
        } else {
            this.text = this.i18n.getPlural(this.key, this.plural, this.content, this.variables, this.domain);
        }
    }
}

用法示例:

<i18n key="FOO_KEY" domain="stackoverflow">I'm the default value !</i18n>

我知道<ng-content></ng-content>可以工作，但仅在模板逻辑上有效，我需要一种方法来使孩子在打字稿中成为字符串.

I know <ng-content></ng-content> works but only on the template logic, I need a way to get child as string in typescript.

已经尝试过@ContentChild(String)，但是我得到了undefined.

Already tried @ContentChild(String) but I got undefined.

另一种方法是像在索引的基本app组件中包含的"Loading ..."字符串一样，充当占位符，直到加载完所有内容为止.我可以为I18n做同样的事情，在我从服务人员那里得到一些东西替换它之前，请先将花边保持器放在这里，但我不知道该如何实现.

Another way would be to do it like "Loading..." string you can have in the base app component in the index, acting like a placeholder until you get everything loaded. I could do the same for I18n, let the laceholder here until I get something from service to replace it, but I don't know how to achieve this.

推荐答案

您不能使用@ContentChildren()来获取全部内容.您可以添加模板变量并查询其名称:

You can't use @ContentChildren() to get the whole content. You can either add a template variable and query for its name:

<i18n key="FOO_KEY" domain="stackoverflow"><span #myVar>I'm the default value !</span></i18n>

@ContentChild('myVar') myVar;

ngAfterContentInit() {
  console.log(this.myVar.nativeElement.innerHTML);
}

myVar不会在调用ngAfterContentInit()之前初始化.

myVar will not be initialized before ngAfterContentInit() is called.

或者，您可以查询@ContentChild()(或@ContentChildren())类似的组件类型

Alternatively @ContentChild() (or @ContentChildren()) you can query for a components type like

    <i18n key="FOO_KEY" domain="stackoverflow"><my-comp>I'm the default value !</my-comp></i18n>

@ContentChild(MyComponent, {read: ElementRef}) mycomp;

ngAfterContentInit() {
  console.log(this.myVar.nativeElement.innerHTML);
}

我认为这种方法对您来说会更好

I think this approach will work better for you approach

@Component({
    selector: "i18n",
    template: "<div #wrapper hidden="true"><ng-content></ng-content><div>{{text}}",
})
export class I18nComponent implements OnInit {

    constructor(private i18n:I18n) {
    }

    @ViewChild('wrapper') content:ElementRef; //Here, I want to store actual value as fallback one.

    @Input('key') key:string;

    @Input('domain') domain:string;

    @Input('variables')
    variables:Variables = [];

    @Input("plural")
    plural:number;

    text:string;

    ngAfterViewInitInit():any {
        console.log(this.content.nativeElement.innerHTML);
        if (this.plural !== undefined && this.plural != null) {
            this.text = this.i18n.get(this.key, this.content, this.variables, this.domain);
        } else {
            this.text = this.i18n.getPlural(this.key, this.plural, this.content, this.variables, this.domain);
        }
    }
}

如果您希望i18n组件的用户能够使用Angular绑定，组件和指令，则在它们传递给<i18n>的内容中，则他需要将其包装在模板中.

If you want the users of your i18n component to be able to use Angular bindings, components, and directives, in the content they pass to <i18n>, then he needs to wrap it in a template.

    <i18n key="FOO_KEY" domain="stackoverflow">
      <template>
        I'm the {{someName}}!
        <my-comp (click)="doSomething()"></my-comp>
      </template>
    </i18n>

如 https://stackoverflow.com/a/372​​29495/217408

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