Display the view component (table) once the service call is complete and the array containing table information has been successfully pushed

Creating a dynamic table for my application has been quite challenging. I've implemented @Input parameters to pass crucial information such as headers and elements for the table.

The input structure for the generic table component is as follows:

@Input()
public tableElementsList: any = [];

@Input()
public headerTitles = [];

@Input()
public maxRecordCount: number;

To utilize the table component, it's called in the following manner:

<table-component [tableElementsList]="arrayElements"
[headerTitles]=headElementsArray maxRecordCount=5></table-component>

In order to populate the "arrayElements" array with data queried from the database using a service, the service is invoked within the onInit method of the page.

ngOnInit() {
     this.myService.queryDataFromDatabase().subscribe(
        (data: ObjectDTO[]) => {
            data.forEach((objectDTO: ObjectDTO) => {
                this.arrayElements.push(objectDTO);
            });
        },
        error => {
            console.log(error);
        }
    );
}

The problem arises when the table component loads before the service call is completed, resulting in an empty "arrayElements". This mini-conundrum stems from JavaScript's asynchronous nature, leaving me pondering on how to ensure the table component waits for the data to be loaded into the array before rendering.

Answer №1

Update your HTML to include the following code:

<tabla-component *ngIf="arrayElements" [listaElementosTabla]="arrayElements"
[titulosCabecera]=headElementsArray cantidadMaximaRegistros=5></tabla-component>

This modification ensures that the table component will only be displayed when the list is not empty.

Answer №2

Here's a handy trick: create a "flag" that can toggle the visibility of a table element.

Consider this approach:

In your HTML view:

<div *ngIf="dataLoaded"> 
   <!-- The element inside this div will only show if this flag is True -->
   <table-component [tableElements]="arrayElements"
   [headerTitles]=headElementsArray [maxRecordsToShow]=5></table-component>
</div>

In your TypeScript file:

dataLoaded: boolean = false; // By default, set to false for hidden
ngOnInit() {
     this.myService.queryDataFromDb().subscribe(
        (data: DataObject[]) => {
            data.forEach((dataObject: DataObject) => {
                this.arrayElements.push(dataObject);
            });
            this.dataLoaded = true;
        },
        error => {
            console.log(error);
            this.dataLoaded = false;
        }
    );
}

This setup ensures that the dataLoaded flag remains false (invisible) until after fetching data with an HTTP request.

I hope this explanation proves helpful.

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