Fix: Don't add null values to query string. (#5108)

* feat: add  boolean flag to mimic pre 1.x behavior for paramsSerializer custom function

* chore: update ParamsSerializer Readme

* fix: dont slice hash off URL if not appending params

* Omit nulls from formData serialization

* fix: dont add nulls or undefined values to arrays either

* readme update

* fix test

* chore: documentation

* chore: do TS properly

Co-authored-by: Jay <jasonsaayman@gmail.com>

test/specs/helpers/buildURL.spec.js

@@ -8,10 +8,31 @@ describe('helpers::buildURL', function () {
 
   it('should support params', function () {
     expect(buildURL('/foo', {
-      foo: 'bar'
+      foo: 'bar',
+      isUndefined: undefined,
+      isNull: null
     })).toEqual('/foo?foo=bar');
   });
 
+  it('should support sending raw params to custom serializer func', function () {
+        const serializer = sinon.stub();
+        const params = { foo: "bar" };
+        serializer.returns("foo=bar");
+    expect(
+      buildURL(
+        "/foo",
+        {
+          foo: "bar",
+        },
+        {
+          serialize: serializer,
+        }
+      )
+    ).toEqual("/foo?foo=bar");
+    expect(serializer.calledOnce).toBe(true);
+    expect(serializer.calledWith(params)).toBe(true);
+  });
+
   it('should support object params', function () {
     expect(buildURL('/foo', {
       foo: {
@@ -30,7 +51,7 @@ describe('helpers::buildURL', function () {
 
   it('should support array params', function () {
     expect(buildURL('/foo', {
-      foo: ['bar', 'baz']
+      foo: ['bar', 'baz', null, undefined]
     })).toEqual('/foo?foo[]=bar&foo[]=baz');
   });
 

test/typescript/axios.ts

@@ -6,7 +6,7 @@ import axios, {
   AxiosAdapter,
   Cancel,
   CancelTokenSource,
-  Canceler, AxiosProgressEvent
+  Canceler, AxiosProgressEvent, ParamsSerializerOptions
 } from 'axios';
 
 const config: AxiosRequestConfig = {
@@ -21,8 +21,8 @@ const config: AxiosRequestConfig = {
   params: { id: 12345 },
   paramsSerializer: {
     indexes: true,
-    encode: (value) => value,
-    serialize: (value, options) => String(value)
+    encode: (value: any) => value,
+    serialize: (value: Record<string, any>, options?: ParamsSerializerOptions) => String(value)
   },
   data: { foo: 'bar' },
   timeout: 10000,