Ajax: Support binary data (including FormData)

Two changes have been applied:
* prefilters are now applied before data is converted to a string;
  this allows prefilters to disable such a conversion
* a prefilter for binary data is added; it disables data conversion
  for non-string non-plain-object `data`; for `FormData` bodies, it
  removes manually-set `Content-Type` header - this is required
  as browsers need to append their own boundary to the header

Ref gh-4150
Closes gh-5197

package.json

@@ -55,6 +55,7 @@
     "karma-qunit": "4.1.2",
     "karma-webkit-launcher": "2.1.0",
     "load-grunt-tasks": "5.1.0",
+    "multiparty": "4.2.3",
     "native-promise-only": "0.8.1",
     "playwright-webkit": "1.29.2",
     "promises-aplus-tests": "2.1.2",

src/ajax.js

@@ -562,14 +562,14 @@ jQuery.extend( {
 			}
 		}
 
+		// Apply prefilters
+		inspectPrefiltersOrTransports( prefilters, s, options, jqXHR );
+
 		// Convert data if not already a string
 		if ( s.data && s.processData && typeof s.data !== "string" ) {
 			s.data = jQuery.param( s.data, s.traditional );
 		}
 
-		// Apply prefilters
-		inspectPrefiltersOrTransports( prefilters, s, options, jqXHR );
-
 		// If request was aborted inside a prefilter, stop there
 		if ( completed ) {
 			return jqXHR;

src/ajax/binary.js

@@ -0,0 +1,17 @@
+import jQuery from "../core.js";
+
+import "../ajax.js";
+
+jQuery.ajaxPrefilter( function( s ) {
+
+	// Binary data needs to be passed to XHR as-is without stringification.
+	if ( typeof s.data !== "string" && !jQuery.isPlainObject( s.data ) ) {
+		s.processData = false;
+	}
+
+	// `Content-Type` for requests with `FormData` bodies needs to be set
+	// by the browser as it needs to append the `boundary` it generated.
+	if ( s.data instanceof window.FormData ) {
+		s.contentType = false;
+	}
+} );

src/jquery.js

@@ -23,6 +23,7 @@ import "./ajax.js";
 import "./ajax/xhr.js";
 import "./ajax/script.js";
 import "./ajax/jsonp.js";
+import "./ajax/binary.js";
 import "./ajax/load.js";
 import "./core/parseXML.js";
 import "./core/parseHTML.js";

test/data/mock.php

@@ -124,6 +124,17 @@ QUnit.assert.ok( true, "mock executed");';
 		echo "$cleanCallback($text)\n";
 	}
 
+	protected function formData( $req ) {
+		$prefix = 'multipart/form-data; boundary=--';
+		$contentTypeValue = $req->headers[ 'CONTENT-TYPE' ];
+		if ( substr( $contentTypeValue, 0, strlen( $prefix ) ) === $prefix ) {
+			echo 'key1 -> ' . $_POST[ 'key1' ] . ', key2 -> ' . $_POST[ 'key2' ];
+		} else {
+			echo 'Incorrect Content-Type: ' . $contentTypeValue .
+				"\nExpected prefix: " . $prefix;
+		}
+	}
+
 	protected function error( $req ) {
 		header( 'HTTP/1.0 400 Bad Request' );
 		if ( isset( $req->query['json'] ) ) {

test/data/testinit.js

@@ -174,8 +174,11 @@ function url( value ) {
 }
 
 // Ajax testing helper
-this.ajaxTest = function( title, expect, options ) {
-	QUnit.test( title, function( assert ) {
+this.ajaxTest = function( title, expect, options, wrapper ) {
+	if ( !wrapper ) {
+		wrapper = QUnit.test;
+	}
+	wrapper.call( QUnit, title, function( assert ) {
 		assert.expect( expect );
 		var requestOptions;
 

test/middleware-mockserver.js

@@ -3,6 +3,7 @@
 const url = require( "url" );
 const fs = require( "fs" );
 const getRawBody = require( "raw-body" );
+const multiparty = require( "multiparty" );
 
 let cspLog = "";
 
@@ -141,6 +142,19 @@ const mocks = {
 		resp.writeHead( 200 );
 		resp.end( `${ cleanCallback( callback ) }(${ JSON.stringify( body ) })\n` );
 	},
+	formData: function( req, resp, next ) {
+		const prefix = "multipart/form-data; boundary=--";
+		const contentTypeValue = req.headers[ "content-type" ];
+		resp.writeHead( 200 );
+		if ( ( prefix || "" ).startsWith( prefix ) ) {
+			getMultiPartContent( req ).then( function( { fields = {} } ) {
+				resp.end( `key1 -> ${ fields.key1 }, key2 -> ${ fields.key2 }` );
+			}, next );
+		} else {
+			resp.end( `Incorrect Content-Type: ${ contentTypeValue
+				}\nExpected prefix: ${ prefix }` );
+		}
+	},
 	error: function( req, resp ) {
 		if ( req.query.json ) {
 			resp.writeHead( 400, { "content-type": "application/json" } );
@@ -363,4 +377,18 @@ function getBody( req ) {
 		} );
 }
 
+function getMultiPartContent( req ) {
+	return new Promise( function( resolve ) {
+		if ( req.method !== "POST" ) {
+			resolve( "" );
+			return;
+		}
+
+		const form = new multiparty.Form();
+		form.parse( req, function( _err, fields, files ) {
+			resolve( { fields, files } );
+		} );
+	} );
+}
+
 module.exports = MockserverMiddlewareFactory;

test/unit/ajax.js

@@ -3105,4 +3105,47 @@ if ( typeof window.ArrayBuffer === "undefined" || typeof new XMLHttpRequest().re
 		assert.ok( jQuery.active === 0, "ajax active counter should be zero: " + jQuery.active );
 	} );
 
+	ajaxTest( "jQuery.ajax() - FormData", 1, function( assert ) {
+		var formData = new FormData();
+		formData.append( "key1", "value1" );
+		formData.append( "key2", "value2" );
+
+		return {
+			url: url( "mock.php?action=formData" ),
+			method: "post",
+			data: formData,
+			success: function( data ) {
+				assert.strictEqual( data, "key1 -> value1, key2 -> value2",
+					"FormData sent correctly" );
+			}
+		};
+	} );
+
+	ajaxTest( "jQuery.ajax() - URLSearchParams", 1, function( assert ) {
+		var urlSearchParams = new URLSearchParams();
+		urlSearchParams.append( "name", "peter" );
+
+		return {
+			url: url( "mock.php?action=name" ),
+			method: "post",
+			data: urlSearchParams,
+			success: function( data ) {
+				assert.strictEqual( data, "pan", "URLSearchParams sent correctly" );
+			}
+		};
+	}, QUnit.testUnlessIE );
+
+	ajaxTest( "jQuery.ajax() - Blob", 1, function( assert ) {
+		var blob = new Blob( [ "name=peter" ], { type: "text/plain" } );
+
+		return {
+			url: url( "mock.php?action=name" ),
+			method: "post",
+			data: blob,
+			success: function( data ) {
+				assert.strictEqual( data, "pan", "Blob sent correctly" );
+			}
+		};
+	} );
+
 } )();