Ways to transfer a value from an HTML element to be accessed by other functions within a TypeScript component

I am facing an issue where I have a dropdown menu, and I need to pass the ID of the selected value ($event.target.value) to other functions in different components.

 <div class="dropdown  ml-auto">
   <select  (change)=getSelectedVariantProject($event.target.value)>
      <option value = "default">Select project</option>
      <option *ngFor = "let project of selectProject" value = {{project.projectId}}>{{project.projectName}}</option>
   </select>
 </div>

In my project service, I have two important functions:

getProjects(): Observable<any>{
    return this.http.get<Project>(this.urlProject)
    .pipe(
    catchError(this.handleError('getProject',[]))
  );
  }

  getProjectVariant(id: number): Observable<any>{
    var url = this.urlProjectVariant;
    url = url + id;
    return this.http.get<ProjectVariant>(url)
      .pipe(
        catchError(this.handleError('getProjectVariant',[]))
      )
  }

Furthermore, in my table component, I require the ID value from HTML as an argument named projectVariantId :

export class TablesComponent implements OnInit {

  filters: MisraLint;
  pageMisraMessages: PageMisraLintTable;
  selectedPage : number = 0;
  buildId: number = 1;
  sizeTableEntries: number = 100;
  page: any;

  constructor(private misraService: MisraService) { }

  getFilters(): void{  
    this.misraService.getMisraLintFilters(2)
      .subscribe(filters => this.filters = filters);
  }

  getPageMisra(page:number,projectVariantId: number,size:number,buildId:number): void{
    this.misraService.getPageMisraLint(page,projectVariantId, size,buildId)
      .subscribe(pageMisra => {
        this.pageMisraMessages = pageMisra
        console.log("Misra messages: " + pageMisra.content)
      })

  }

  getMisraLintByFilters(page: number, projectVariantId: number, size:number, filter: string)
  {
       //call rest API to apply filters
   this.misraService.getMisraLintByFilters(page,projectVariantId,size,filter)
   .subscribe(pageMisra => {
     this.pageMisraMessages = pageMisra
   })
  }

  ngOnInit() {
    this.getFilters();
    this.getPageMisra(0,2,this.sizeTableEntries,this.buildId);
  }
}

I am unsure how to approach this problem. How can I properly pass $event.target.value as an argument to other component functions in TypeScript when a user selects an option from the dropdown menu?

Answer №1

Method 1.) If you have another component on the same page

In component.ts

selectedItem = null;

getSelectedVariantItem(id){
 this.selectedItem = id;
}

in component.html

<app-other-component selectedItem="selectedItem"></app-other-component>

In otherComponent.ts

@Input() selectedItem;

Method 2.) If the other component is on a different page, you can utilize a service.

In component.ts

constructor(private itemService: ItemService) {

}

getSelectedVariantItem(id){
     this.itemService.selectedItem = id;
}

In otherComponent.ts

constructor(private itemService: ItemService) {
 console.log(this.itemService.selectedItem);
}

Answer №2

Here is a suggestion for you:

<select (change)=getSelectedVariantProject($event.target.value)>

To handle this, consider adding a variable like selectedvariant in your component, or use it directly in the function as shown below:

getSelectedVariantProject(val){//your code here}
Remember that (val) represents $event.target.value.

For instance:

selectedvariant:any = val;

or

if(condition === condition_equal_to_whatever
valusage

For additional information, check out this link

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