Having trouble using the RxJS filter to sort through records effectively

Question

Having trouble using the RxJS filter to sort through records effectively

Despite using the rxjs filter in my angular project, I'm encountering difficulties in filtering records. Here is the function in question:

public getOrders(type: string, filterObj = {}, otherParams = {}): Observable<{ name: string; qt: number }[]> {
   return this.http.get(apiUrl, { params: { filter: JSON.stringify(filterObj), ...otherParams},
   })
   .pipe(map((res: any) => res.payload))
   .pipe(filter((order: any) => order.name && /\S/.test(order.name)));
}

The current implementation is not yielding the expected results. No values are being returned.

However, when I make the following adjustment, the code functions as intended:

public getOrders(type: string, filterObj = {}, otherParams = {}): Observable<{ name: string; qt: number }[]> {
   return this.http.get(apiUrl, { params: { filter: JSON.stringify(filterObj), ...otherParams},
   })
   .pipe(map((res: any) => res.payload.filter((order: any) => order.name && /\S/.test(order.name))))
}

What could be causing the issue here?

angular typescript rxjs

Answer 1

Answer №1

There is a distinction between using rxjs filter and the Array.filter.

The rxjs filter function is designed to filter out observable emissions that are not required - especially in situations where the source observable emits multiple values (unlike with httpClient.get)

On the other hand, the Array.filter method allows you to filter elements within an array based on specified criteria. This method returns an array containing only the elements that meet the filter criteria. To implement this properly, you can use code similar to the following:

public getOrders(
  type: string,
  filterObj = {},
  otherParams = {}
): Observable<{ name: string; qt: number }[]> {
  return this.http
    .get(apiUrl, {
      params: { filter: JSON.stringify(filterObj), ...otherParams },
    })
    .pipe(
      map((res: any) => res.payload),
      map((orders) =>
        orders.filter((order: any) => order.name && /\S/.test(order.name))
      )
    );
}

You can also choose to remove the second map operator and adopt the approach that worked correctly before.

Answer 2

There is a distinction between using rxjs filter and the Array.filter.

The rxjs filter function is designed to filter out observable emissions that are not required - especially in situations where the source observable emits multiple values (unlike with httpClient.get)

On the other hand, the Array.filter method allows you to filter elements within an array based on specified criteria. This method returns an array containing only the elements that meet the filter criteria. To implement this properly, you can use code similar to the following:

public getOrders(
  type: string,
  filterObj = {},
  otherParams = {}
): Observable<{ name: string; qt: number }[]> {
  return this.http
    .get(apiUrl, {
      params: { filter: JSON.stringify(filterObj), ...otherParams },
    })
    .pipe(
      map((res: any) => res.payload),
      map((orders) =>
        orders.filter((order: any) => order.name && /\S/.test(order.name))
      )
    );
}

You can also choose to remove the second map operator and adopt the approach that worked correctly before.

Answer 3

Answer №2

It appears that your payload is in the form of an array, which is likely why it is not functioning as intended.

Essentially, what you are doing is

const arr:any = [];
if(arr.name){///whatever}

Does this explanation make sense? Probably not.

Your filter function is operating correctly, but your code structure is incorrect. This is why I previously mentioned

In my Angular project, I am having issues with an rxjs filter that is not performing as expected.

This statement emphasizes the issue at hand.

Avoid overusing any and instead utilize TypeScript's typing system (which is its main strength) to prevent similar problems in the future.

Answer 4

It appears that your payload is in the form of an array, which is likely why it is not functioning as intended.

Essentially, what you are doing is

const arr:any = [];
if(arr.name){///whatever}

Does this explanation make sense? Probably not.

Your filter function is operating correctly, but your code structure is incorrect. This is why I previously mentioned

In my Angular project, I am having issues with an rxjs filter that is not performing as expected.

This statement emphasizes the issue at hand.

Avoid overusing any and instead utilize TypeScript's typing system (which is its main strength) to prevent similar problems in the future.

Having trouble using the RxJS filter to sort through records effectively

Answer №1

Answer №2

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