How to create n level nested expand/collapse component dynamically in angular

Question

I am developing a script of n-level of nested tables using div.

So there are 5 to 6 columns with n number of rows, every first column have to expand/collapse button, on click of which I make a call to API which gives me data respective to selected row filters.

Previously when I worked with core JavaScript and jQuery, I was using find method of document selector to identify the parent of expand/collapse button and push dynamically created HTML after that specific div only using innerHTML or append method of jQuery

I am a bit new to angular and haven't worked much. Please help me to solve this.

splitOpt is an array of objects based on which I will split report data.

this.splitOpt = [
    {
        id: "country",
        label: "Country"
    },
    {
        id:"os".
        label:"Operating System"
    },
    {
        id:"osv".
        label:"Operating System Version"
    }
]

Function to get reports

getReport() {

    // apiFilters are array of object having some values to filter report data  
    var apiFilters: any = [{}];
    for (var i = 0; i < this.sFilters.length; i++) {

        if (this.sFilters[i][0].values.length > 0) {
            var k;
            k = this.sFilters[i][0].id
            apiFilters[0][k] = this.sFilters[i][0].values;
        }
    }

    var split = this.splitOpt[0].id;
    this._apis.getReportData(split, apiFilters[0]).subscribe(response => {
        if (response.status == 1200) {
            this.reportData = response.data.split_by_data;
        }
    })
}

Function to check if there are more splits or not

checkIfHaveMoreSplits(c){
      if(this.splitOpt.length > 0) {
        var index = this.splitOpt.findIndex(function(v) {
          return v.id == c
        })

       if (typeof(this.splitOpt[index+1]) != "undefined"){
         return this.splitOpt[index+1];
       } else {
        return 0;
       }
   }

    }

Code to draw table based on split and report data.

Let's assume there is only one object for the country in splitopt object than checkIfHaveMoreSplits() returns 0 which means I do not have to give expand button and if it is not 0 that expand button will appear there.

Onclick of expanding button I will select next element from splitopt and call API to get report having split param as a carrier and so on.

<div class="table" >
<div class="row" *ngFor="let rData of reportData; let i = index;" >
        <div class="col" >

            <button 
                 class="btn btn-sm" 
                 *ngIf="checkIfHaveMoreSplits(splitbykey) !== 0"
                 (click)="splitData(splitbykey)"
                >+</button>
            {{rData[splitbykey]}}
        </div>
        <div class="col">{{rData.wins}}</div>
        <div class="col">{{rData.conversions}}</div>
        <div class="col">{{rData.cost}}</div>
        <div class="col">{{rData.bids}}</div>
        <div class="col">{{rData.impressions}}</div>
        <div class="col">{{rData.rev_payout}}</div>

</div>

I am managing one array which identifies how deep I can expand collapse element

Let us assume that array has three elements namely country, carrier, and os

So first table which I will draw having all the countries in the table with expand button on click of which I will send selected country and get carriers of that specific country. After getting the response I want to create custom HTML based on response and append html after selected row.

Here are the screenshots as well consist of full workflow :)

Step 1

Step 2

Step 3

Answer 1

I'd propose writing a custom angular component for each of your dynamic HTML pieces you want to display. Then you can write a recurrent component that will *ngIf your nested components based on a type list you provide. Like so:

// dynamic.component.ts

export type DynamicComponentType = 'country' | 'os' | 'osv';
export interface IOptions { /* whatever options you need for your components */ }
export type DynamicComponentOptions = { type: DynamicComponentType, options: IOptions};

@Component({
  selector: 'app-dynamic',
  template = `
    <app-country *ngIf="current.type == 'country'" [options]="current.options" />
    <app-os *ngIf="current.type == 'os'" [options]="current.options" />
    <app-osv *ngIf="current.type == 'osv'" [options]="current.options" />
    <ng-container *ngIf="!!subTypes"> 
      <button (click)="dynamicSubComponentShow = !dynamicSubComponentShow" value="+" />
      <app-dynamic *ngIf="dynamicSubComponentShow" [options]="subOptions" />
    </ng-container>`,
  // other config
})
export class DynamicComponent {

  @Input() options: DynamicComponentOptions[];

  get current(): DynamicComponentOptions { 
    return this.options && this.options.length && this.options[0]; 
  }
  get subOptions(): DynamicComponentOptions[] {
    return this.options && this.options.length && this.options.slice(1);
  }

  dynamicSubComponentShow = false;

  // component logic, other inputs, whatever else you need to pass on to the specific components
}

Example for CountryComponent. The other components will look similar.

// country.component.ts

@Component({
  selector: 'app-country',
  template: `
    <div>Country label</div>
    <p>Any other HTML for the country component using the `data` observable i.e.</p>
    <span>x: {{ (data$ | async)?.x }}</span>
    <span>y: {{ (data$ | async)?.y }}</span>
  `,
})
export class CountryComponent {

  @Input() options: IOptions;

  data$: Observable<{x: string, y: number}>;

  constructor(private countryService: CountryService) {
    // load data specific for this country based on the input options
    // or use it directly if it already has all your data
    this.data$ = countryService.getCountryData(this.options);
  }
}

// my.component.ts

@Component({
  template: `
    <div class="table" >
      <div class="row" *ngFor="let rData of reportData$ | async; let i = index;" >
        <div class="col" >
          <app-dynamic [options]="options$ | async"></app-dynamic>
        </div>
        ...
      </div>
    </div>`,
  // other cmp config
})
export class MyComponent {

  options$: Observable<DynamicComponentOptions[]>;
  reportData$: Observable<ReportData>;

  constructor(private reportService: ReportService){

    // simplified version of your filter calculation
    let apiFilters: {} = this.sFilters
      .map(f => f[0])
      .filter(f => f && f.values && f.values.length)
      .reduce((f, acc) => acc[f.id] = f.values && acc, {});

    this.reportData$ = reportService.getReportData(this.splitOpt[0].id, apiFilters).pipe(
      filter(r => r.status == 1200),
      map(r => r.data.split_by_data)
    );
    this.options$ = this.reportData$.pipe(map(d => d.YOUR_OPTIONS));
  }
}

Now make your api return something like

{
  "status": 1200,
  "data": {
    "YOUR_OPTIONS": [{
      "type": "country"
      "options" { "id": 1, ... } // options for your country component initialization
    }, {
      "type": "os",
      "options" { "id": 11, ... } // options for your os component initialization
    }, ...],
    // your other report data for the main grid
  }
}

Please, adjust this to your specific needs. You will have to manage passing of state through the component hierarchy for example (using component state, observable services, MobX, NgRx - pick your poison).

Hope this helps a little :-)

Answer 2

I'm not putting the solution here as I do not know what you js code is. But you might want to consider using ViewContainerRef to append elements dynamically. Hope this helps