feat(common): implement `appendAll()` method on `HttpParams` (#20930)

Adds an `appendAll()` method to `HttpParams` that can construct the HTTP
request/response body from an object of parameters and values.

This avoids calling `append()` multiple times when multiple parameters
need to be added.

Fixes #20798

PR Close #20930

goldens/public-api/common/http/http.d.ts

@@ -1570,6 +1570,9 @@ export declare interface HttpParameterCodec {
 export declare class HttpParams {
     constructor(options?: HttpParamsOptions);
     append(param: string, value: string): HttpParams;
+    appendAll(params: {
+        [param: string]: string | string[];
+    }): HttpParams;
     delete(param: string, value?: string): HttpParams;
     get(param: string): string | null;
     getAll(param: string): string[] | null;

packages/common/http/src/params.ts

@@ -209,6 +209,26 @@ export class HttpParams {
     return this.clone({param, value, op: 'a'});
   }
 
+  /**
+   * Constructs a new body with appended values for the given parameter name.
+   * @param params parameters and values
+   * @return A new body with the new value.
+   */
+  appendAll(params: {[param: string]: string|string[]}): HttpParams {
+    const updates: Update[] = [];
+    Object.keys(params).forEach(param => {
+      const value = params[param];
+      if (Array.isArray(value)) {
+        value.forEach(_value => {
+          updates.push({param, value: _value, op: 'a'});
+        });
+      } else {
+        updates.push({param, value, op: 'a'});
+      }
+    });
+    return this.clone(updates);
+  }
+
   /**
    * Replaces the value for a parameter.
    * @param param The parameter name.
@@ -251,10 +271,10 @@ export class HttpParams {
         .join('&');
   }
 
-  private clone(update: Update): HttpParams {
+  private clone(update: Update|Update[]): HttpParams {
     const clone = new HttpParams({encoder: this.encoder} as HttpParamsOptions);
     clone.cloneFrom = this.cloneFrom || this;
-    clone.updates = (this.updates || []).concat([update]);
+    clone.updates = (this.updates || []).concat(update);
     return clone;
   }
 

packages/common/http/test/params_spec.ts

@@ -36,6 +36,12 @@ import {HttpParams} from '@angular/common/http/src/params';
         expect(mutated.toString()).toEqual('a=b&a=c');
       });
 
+      it('should allow appending all parameters', () => {
+        const body = new HttpParams({fromString: 'a=a1&b=b1'});
+        const mutated = body.appendAll({a: ['a2', 'a3'], b: 'b2'});
+        expect(mutated.toString()).toEqual('a=a1&a=a2&a=a3&b=b1&b=b2');
+      });
+
       it('should allow deletion of parameters', () => {
         const body = new HttpParams({fromString: 'a=b&c=d&e=f'});
         const mutated = body.delete('c');