Tips for effectively utilizing URLSearchParams in Angular 5 HttpClient's "get" function

Question

Tips for effectively utilizing URLSearchParams in Angular 5 HttpClient's "get" function

When working with Angular 4.2, I used the Http service and made use of the get method by passing in a URLSearchParams object as the search parameter:

this.http.get(url, {headers: this.setHeaders(), search: params})

Now I am looking to upgrade to Angular 5 where http has been replaced by HttpClient as recommended by the Angular team. However, I encountered an error related to the 'search' key.

Can you provide guidance on how to migrate from Http to HttpClient service in my specific scenario?

Appreciate your assistance.

angular typescript http angular5 httpclient

Answer 1

Answer №1

Starting from Angular version 4.3, you can utilize the HttpClient in the following manner:

import { HttpClient,HttpHeaders, HttpParams } from '@angular/common/http';

   constructor(private httpClient: HttpClient) { }    

   getData(){
        let headers = new HttpHeaders();
        headers  = headers.append('header-1', 'value-1');
        headers  = headers.append('header-2', 'value-2');

       let params = new HttpParams();
       params = params.append('param-1', 'value-1');
       params = params.append('param-2', 'value-2');

       this.httpClient.get("/data", {headers , params })
   }

The classes HttpParams and HttpHeaders are immutable, meaning that after each call to the set or append methods, a new instance is returned. Therefore, it's important to do this: params = params.append(...)

Answer 2

Starting from Angular version 4.3, you can utilize the HttpClient in the following manner:

import { HttpClient,HttpHeaders, HttpParams } from '@angular/common/http';

   constructor(private httpClient: HttpClient) { }    

   getData(){
        let headers = new HttpHeaders();
        headers  = headers.append('header-1', 'value-1');
        headers  = headers.append('header-2', 'value-2');

       let params = new HttpParams();
       params = params.append('param-1', 'value-1');
       params = params.append('param-2', 'value-2');

       this.httpClient.get("/data", {headers , params })
   }

The classes HttpParams and HttpHeaders are immutable, meaning that after each call to the set or append methods, a new instance is returned. Therefore, it's important to do this: params = params.append(...)

Answer 3

Answer №2

Comparison of Angular 4 and Angular 5:

this.http.get(url, {headers: this.setHeaders(), search: params})

New Method in Angular 5:

import { HttpClient, HttpParams } from '@angular/common/http';
let params = new HttpParams().set('paramName', paramValue);
this.http.get(url,  { params: params })

Handling Multiple Parameters:

// Initialize Params Object
let Params = new HttpParams();

// Assign multiple parameters
Params = Params.append('firstParameter', firstVal);
Params = Params.append('secondParameter', secondVal);

Answer 4

Comparison of Angular 4 and Angular 5:

this.http.get(url, {headers: this.setHeaders(), search: params})

New Method in Angular 5:

import { HttpClient, HttpParams } from '@angular/common/http';
let params = new HttpParams().set('paramName', paramValue);
this.http.get(url,  { params: params })

Handling Multiple Parameters:

// Initialize Params Object
let Params = new HttpParams();

// Assign multiple parameters
Params = Params.append('firstParameter', firstVal);
Params = Params.append('secondParameter', secondVal);

Answer 5

Answer №3

Here are the steps you need to follow in order to make the necessary changes:

Replace the older Http import with:

import { HttpClient } from "@angular/common/http";
Create an instance of HttpClient as shown below:

constructor( protected httpClient: HttpClient, ) {}

There are various methods to implement search parameters, such as:

public get(searchParam: string): Observable { return this.httpClient.get(${this.URL}/${searchParam}); }

Alternatively, you can also use the following approach:

public get(searchParam: string): Observable<object> {
let headers = new Headers({ 'Content-Type': 'application/json' });
    let myParams = HttpParams().set("id", searchParam);

    let options = new RequestOptions({ headers: headers, method: 'get', params: myParams });

return this.http.get("this.url",options)
         .map((res: Response) => res.json())
         .catch(this.handleError);
}

Answer 6

Here are the steps you need to follow in order to make the necessary changes:

Replace the older Http import with:

import { HttpClient } from "@angular/common/http";
Create an instance of HttpClient as shown below:

constructor( protected httpClient: HttpClient, ) {}

There are various methods to implement search parameters, such as:

public get(searchParam: string): Observable { return this.httpClient.get(${this.URL}/${searchParam}); }

Alternatively, you can also use the following approach:

public get(searchParam: string): Observable<object> {
let headers = new Headers({ 'Content-Type': 'application/json' });
    let myParams = HttpParams().set("id", searchParam);

    let options = new RequestOptions({ headers: headers, method: 'get', params: myParams });

return this.http.get("this.url",options)
         .map((res: Response) => res.json())
         .catch(this.handleError);
}

Answer 7

Answer №4

In one instance, I encountered a scenario where multiple parameters needed to be passed to the api. The approach that proved successful for me was chaining set() method calls in the same line during the initialization of the HttpParams object:

public fetchData(userID: string, userName: string): Observable<object> {
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let myParams = HttpParams().set("id", userID).set("username", userName);
    let options = new RequestOptions({ headers: headers, method: 'get', params: 
myParams });

Answer 8

In one instance, I encountered a scenario where multiple parameters needed to be passed to the api. The approach that proved successful for me was chaining set() method calls in the same line during the initialization of the HttpParams object:

public fetchData(userID: string, userName: string): Observable<object> {
    let headers = new Headers({ 'Content-Type': 'application/json' });
    let myParams = HttpParams().set("id", userID).set("username", userName);
    let options = new RequestOptions({ headers: headers, method: 'get', params: 
myParams });

Answer 9

Answer №5

When using HttpParams, there are two methods available: set(string, string) and append(string, string).

The purpose of set is clearly defined - it replaces the value for a parameter:

let httpParams = new HttpParams();
httpParams = httpParams.set('page', '0');
httpParams = httpParams.set('page', '1');

// httpParams.toString() -> 'page=1'

On the other hand, the description for append seems misleading to me: Appends a new value to existing values for a parameter.

I would expect the following behavior based on the documentation:

let httpParams = new HttpParams();
httpParams = httpParams.add('page', '0');
httpParams = httpParams.add('page', '1');

// httpParams.toString() -> 'page=1,2'

However, in actuality (angular 11.2.14), the behavior is as follows:

let httpParams = new HttpParams();
httpParams = httpParams.add('page', '0');
httpParams = httpParams.add('page', '1');

// httpParams.toString() -> 'page=1&page=2'

Despite this discrepancy, there are still different scenarios that need to be addressed:

page=0&size=10 - can be achieved using the set method of httpParams
```
sort=id,asc&sort=statusId,desc
```
- can be handled using the add method of httpParams
```
search=id>100,id<500,statusId:3
```
- requires manual intervention

Answer 10

When using HttpParams, there are two methods available: set(string, string) and append(string, string).

The purpose of set is clearly defined - it replaces the value for a parameter:

let httpParams = new HttpParams();
httpParams = httpParams.set('page', '0');
httpParams = httpParams.set('page', '1');

// httpParams.toString() -> 'page=1'

On the other hand, the description for append seems misleading to me: Appends a new value to existing values for a parameter.

I would expect the following behavior based on the documentation:

let httpParams = new HttpParams();
httpParams = httpParams.add('page', '0');
httpParams = httpParams.add('page', '1');

// httpParams.toString() -> 'page=1,2'

However, in actuality (angular 11.2.14), the behavior is as follows:

let httpParams = new HttpParams();
httpParams = httpParams.add('page', '0');
httpParams = httpParams.add('page', '1');

// httpParams.toString() -> 'page=1&page=2'

Despite this discrepancy, there are still different scenarios that need to be addressed:

page=0&size=10 - can be achieved using the set method of httpParams
```
sort=id,asc&sort=statusId,desc
```
- can be handled using the add method of httpParams
```
search=id>100,id<500,statusId:3
```
- requires manual intervention

Tips for effectively utilizing URLSearchParams in Angular 5 HttpClient's "get" function

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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