* change params of multipart_params function.

dist/lib/uploader/zui.uploader.js

@@ -774,7 +774,7 @@ else if(r instanceof a){if(r.hasBlob())if(r.getBlob().isDetached())r=d.call(s,r)
                 var params = {};
                 if(options.sendFileName) params[options.sendFileName === true ? 'name' : options.sendFileName] = file.name;
                 if(options.sendFileId) params[options.sendFileId === true ? 'uuid' : options.sendFileId] = file.id;
-                params = $.extend(params, $.isFunction(multipartParamsOption) ? multipartParamsOption(file) : multipartParamsOption);
+                params = $.extend(params, $.isFunction(multipartParamsOption) ? multipartParamsOption(file, params) : multipartParamsOption);
                 uploader.setOption('multipart_params', params);
                 that.callEvent('onBeforeUpload', file);
             },

docs/part/view-uploader.md

@@ -499,9 +499,14 @@ var uploader = $('#myUploader').uploader('zui.uploader');
     }
 }</code></pre>
         <p>当设置为回调函数时会在提交文件之前调用，使用返回值作为附加参数提交到服务器，该回调函数包含一个参数为当前提交的文件对象。</p>
-        <pre><code>function(file) {
+        <pre><code>function(file, params) {
     return {filename: file.name, extension: file.ext};
 }</code></pre>
+        <p>回调函数参数定义如下：</p>
+        <ul>
+          <li><code>file</code>：当前准备上传的文件对象；</li>
+          <li><code>params</code>：当前默认的参数对象，你可以修改这个对象并返回作为新的参数对象。</li>
+        </ul>
       </td>
     </tr>
     <tr>

src/js/uploader.js

@@ -737,7 +737,7 @@
                 var params = {};
                 if(options.sendFileName) params[options.sendFileName === true ? 'name' : options.sendFileName] = file.name;
                 if(options.sendFileId) params[options.sendFileId === true ? 'uuid' : options.sendFileId] = file.id;
-                params = $.extend(params, $.isFunction(multipartParamsOption) ? multipartParamsOption(file) : multipartParamsOption);
+                params = $.extend(params, $.isFunction(multipartParamsOption) ? multipartParamsOption(file, params) : multipartParamsOption);
                 uploader.setOption('multipart_params', params);
                 that.callEvent('onBeforeUpload', file);
             },