What is the reason for the lack of variable assignment within the forEach method in Angular?

Question

What is the reason for the lack of variable assignment within the forEach method in Angular?

I am struggling with assigning a value to the variable "this.qdDias" and returning it. After using subscribe, I am unable to retrieve the value at the end of the method. Despite seeing the value in the console.log(this.qdDias), it becomes undefined when returned.

> obterParametroPrazoMap(nomePrazo: string): number {
>         console.log("Parametro vindo: ", nomePrazo)
>         this.service.obterParametrosgeraisMap().subscribe((data) => {
>             this.listParametrosGerais = data.data;
>             this.listParametrosGerais.forEach((x) =>  (this.listParametrosGerais, x));
>             for (var i = 0; i < this.listParametrosGerais.length; i++) {
>                 console.log("comparado: ", this.listParametrosGerais[i].chavePrimaria.tipoParametro.nomeTipoParametro)
>                 if (this.listParametrosGerais[i].chavePrimaria.tipoParametro.nomeTipoParametro
> === nomePrazo) 
> {   
>                     this.qdDias = this.listParametrosGerais[i].quantidadeDiasPrazo;
>                     console.log(this.qdDias)                    
>                     break
> }
> }
   }                   
);       
return this.qdDias;
     }

Is there a solution to this issue?

angular typescript

Answer 1

Answer №1

return this.qdDias is not within the scope of subscribe. Even if the return statement was inside subscribe(), it would still not work. The issue lies in subscribing to an asynchronous observable

this.service.obterParametrosgeraisMap().subscribe()

while treating it as synchronous.

Is

this.service.obterParametrosgeraisMap()

an observable that requires subscription? If so, it should be

this.service.obterParametrosgeraisMap

.

What does this do?

this.listParametrosGerais.forEach((x) => (this.listParametrosGerais, x));

Why use var? Consider using const or let instead?

This approach might partially work, but you need to determine whether you want to return an observable to extract the value from it or transform it into a promise to maintain the asynchronous pattern. More information can be found here:

    function obterParametroPrazoMap(nomePrazo: string): number {
        console.log('Parameter received: ', nomePrazo);
        let map;
        this.service.obterParametrosgeraisMap.pipe(take(1)).subscribe(data => map = data);

        this.listParametrosGerais = map?.data;
        this.listParametrosGerais.forEach((x) => (this.listParametrosGerais, x));
        for (var i = 0; i < this.listParametrosGerais.length; i++) {
            console.log('compared: ', this.listParametrosGerais[i].primaryKey.parameterType.parameterName);
            if (this.listParametrosGerais[i].primaryKey.parameterType.parameterName === nomePrazo) {
                this.qdDias = this.listParametrosGerais[i].deadlineDays;
                console.log(this.qdDias);
                break;
            }
        }

        return this.qdDias;
    }

Answer 2

return this.qdDias is not within the scope of subscribe. Even if the return statement was inside subscribe(), it would still not work. The issue lies in subscribing to an asynchronous observable

this.service.obterParametrosgeraisMap().subscribe()

while treating it as synchronous.

Is

this.service.obterParametrosgeraisMap()

an observable that requires subscription? If so, it should be

this.service.obterParametrosgeraisMap

.

What does this do?

this.listParametrosGerais.forEach((x) => (this.listParametrosGerais, x));

Why use var? Consider using const or let instead?

This approach might partially work, but you need to determine whether you want to return an observable to extract the value from it or transform it into a promise to maintain the asynchronous pattern. More information can be found here:

    function obterParametroPrazoMap(nomePrazo: string): number {
        console.log('Parameter received: ', nomePrazo);
        let map;
        this.service.obterParametrosgeraisMap.pipe(take(1)).subscribe(data => map = data);

        this.listParametrosGerais = map?.data;
        this.listParametrosGerais.forEach((x) => (this.listParametrosGerais, x));
        for (var i = 0; i < this.listParametrosGerais.length; i++) {
            console.log('compared: ', this.listParametrosGerais[i].primaryKey.parameterType.parameterName);
            if (this.listParametrosGerais[i].primaryKey.parameterType.parameterName === nomePrazo) {
                this.qdDias = this.listParametrosGerais[i].deadlineDays;
                console.log(this.qdDias);
                break;
            }
        }

        return this.qdDias;
    }

Answer 3

Answer №2

This is the solution I came up with:

Promise.resolve(2);
        Promise.all([
           this.service.retrieveGeneralParametersMap()
                .then((list: any) => {
                    this.generalParametersList = list.data;
                })
            ,
 this.service.retrieveSpecificParametersMap()
                .then((list: any) => {
                    this.specificParametersList = list.data;
                })
        ]).then(() => {    
            this.initializeDictionaryVariables();
 });

Answer 4

This is the solution I came up with:

Promise.resolve(2);
        Promise.all([
           this.service.retrieveGeneralParametersMap()
                .then((list: any) => {
                    this.generalParametersList = list.data;
                })
            ,
 this.service.retrieveSpecificParametersMap()
                .then((list: any) => {
                    this.specificParametersList = list.data;
                })
        ]).then(() => {    
            this.initializeDictionaryVariables();
 });

What is the reason for the lack of variable assignment within the forEach method in Angular?

Answer №1

Answer №2

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