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jsonangularangular-pipe
Moshe
Moshe

Reputation: 2684

How to use custom pipes Angular2

I have the following JSON object: http://pastebin.com/1TguvZXc

Here is my Models Component HTML: 

<button *ngFor="let category of categories"    (click)="chooseCategory(this.category)" type="button" name="button" class="btn btn-default" id="{{category}}">
  {{category}}
</button>  
<div *ngFor="let model of models?.models">
  <div *ngFor="let year of model['years']">
    <div *ngFor="let style of year['styles'] | chooseCategory">
        {{model.name}}, {{style.submodel.body }}
   </div>
 </div>

A (pipe?) method from my models.component: 

chooseCategory(selectedCategory: string): void {
    if((selectedCategory === '')) {
      this.filterByPipe.transform(this.models,
                     ['models.years.styles.submodel.body'], selectedCategory);
    }
 }

Additionally, I would like to use the FilterByPipe pipe from ngx-pipes to filter out by category in models.years.styles.submodel.body.

The code from my HTML roduces the following error: 

Unhandled Promise rejection: Template parse errors:
The pipe 'chooseCategory' could not be found ("or="let model of models?.models">
  <div *ngFor="let year of model['years']">
    <div *ngFor="let s[ERROR ->]tyle of year['styles'] | chooseCategory">
        {{model.name}}, {{style.submodel.body }}

Upvotes: 1

Views: 260

Answers (2)

Jaroslaw K.
Jaroslaw K.

Reputation: 5374

I think that you not even read the documentation. Yu should create pipe in this way: 

@Pipe({
    name: 'somePipe'
})
export class SomePipe {

   transform(value: any[]): any[] {
      //some transform code...
   }
}

and then can you call that in HTML file in this way:

<div *ngFor="let elem of elements | somePipe"></div>

Dont forget to declare your pipe in module. 

@NgModule({
   declarations: [ SomePipe ]
})

That's what you use is a method, not a pipe.

If you want to executing pipe depend on (f.e.) button click you should build Pipe with argument:

   @Pipe({
      name: 'somePipe'
   })
   export class SomePipe {
      transform(value: any[], args: any[]): any[] {
         let someFlag: boolean = false;
         if(args && args[0]) someflag = true;
         if(someflag) {
            //some transform code...
         }
      }
   }

to call this pipe in this way

<div *ngFor="let elem of elements | somePipe : yesOrNo"></div>

and then can you use in your component method to click button

yesOrNo: boolean = false;

onClickButton(event: any) {
   event.preventDefault();
   yesOrNo = !yesOrNo;
}

Upvotes: 1

developer033
developer033

Reputation: 24874

Since you're importing the pipe and calling it from a button in your component, you don't need to call the pipe directly in your component. Also, chooseCategory is just a method, not a pipe. Then, remove the pipe from the following line:

<div *ngFor="let style of year['styles'] | chooseCategory">

Upvotes: 1

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