feat: added custom params serializer support; (#5113)

* Added custom params serializer support;

* Added missed semicolon;
Fixed allowUnknown option;

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

lib/core/Axios.js

@@ -47,7 +47,7 @@ class Axios {
 
     config = mergeConfig(this.defaults, config);
 
-    const transitional = config.transitional;
+    const {transitional, paramsSerializer} = config;
 
     if (transitional !== undefined) {
       validator.assertOptions(transitional, {
@@ -57,6 +57,13 @@ class Axios {
       }, false);
     }
 
+    if (paramsSerializer !== undefined) {
+      validator.assertOptions(paramsSerializer, {
+        encode: validators.function,
+        serialize: validators.function
+      }, true);
+    }
+
     // Set config.method
     config.method = (config.method || this.defaults.method || 'get').toLowerCase();
 

lib/helpers/buildURL.js

@@ -44,12 +44,20 @@ export default function buildURL(url, params, options) {
 
   const _encode = options && options.encode || encode;
 
-  const serializerParams = utils.isURLSearchParams(params) ?
-    params.toString() :
-    new AxiosURLSearchParams(params, options).toString(_encode);
+  const serializeFn = options && options.serialize;
 
-  if (serializerParams) {
-    url += (url.indexOf('?') === -1 ? '?' : '&') + serializerParams;
+  let serializedParams;
+
+  if (serializeFn) {
+    serializedParams = serializeFn(params, options);
+  } else {
+    serializedParams = utils.isURLSearchParams(params) ?
+      params.toString() :
+      new AxiosURLSearchParams(params, options).toString(_encode);
+  }
+
+  if (serializedParams) {
+    url += (url.indexOf('?') === -1 ? '?' : '&') + serializedParams;
   }
 
   return url;