Uncaught Ext.JSON.decode(): You're trying to decode an invalid JSON String:

[Jin_NYC]

Hi guys,

I've been using sencha for a while but never find a solution for this error.

The js code is a simple file upload field and a submit button:

    var enter = Ext.create('Ext.form.Panel', {
        frame:false,
        header:false,
        border:false,
        url:'myUpload.jsp',
        title:'MY FORM',
        bodyStyle:'padding:5px 5px 0',
        width:900,
        fieldDefaults:{
            msgTarget:'side'
        },
        items:[
            {
                xtype:'panel',
                title:'loadExclusionsP',
                layout:{
                    type:'hbox',
                    align:'center'
                },
                border:false,
                header:false,
                items:[
                    {
                        xtype:'component',
                        html:'Load CSV on Excel: ',
                        name:'text',
                        width:150
                    },
                    {
                        xtype:'filefield',
                        name:'exclusionsCSV',
                        required: true
                    },
                    {
                        xtype:'button',
                        text:'Load file',
                        handler:function () {
                            var formUp = enter.getForm();
                            if (formUp.isValid()) {
                                formUp.submit({
                                    success: function(form, action) {
                                        Ext.Msg.alert('Success',action.result.msg);
                                    },
                                    failure: function(form,action) {
                                        Ext.Msg.alert('failed',action.result.msg);
                                    }
                                });
                            }else{
                                Ext.Msg.alert('Failure', 'Not valid form');
                            }
                        }
                    }
                ]
            }
        ]
    });

and the server side code is also straight forward:

<%@ page import="java.io.*" %>
<%@ page import="java.util.List" %>
<%@ page import="java.util.Iterator" %>
<%@ page import="org.apache.commons.fileupload.disk.DiskFileItemFactory" %>
<%@ page import="org.apache.commons.fileupload.servlet.ServletFileUpload" %>
<%@ page import="org.apache.commons.fileupload.FileItem" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


<%
    response.setContentType("text/html");


    String result="";
    File file;
    int maxFileSize = 5000 * 1024;
    int maxMemSize = 5000 * 1024;


    DiskFileItemFactory factory = new DiskFileItemFactory();
    factory.setSizeThreshold(maxMemSize);
    factory.setRepository(new File("c:\\temp"));
    ServletFileUpload upload = new ServletFileUpload(factory);
    List<FileItem> items = upload.parseRequest(request);


    FileItem f1 = items.get(0);


     System.out.println(f1.getString());
%>

Can any one see why the error happens, thank you so much for your time and help.

[evant]

A file upload expects you to return a json response the same way you would for a normal form submit.

[Jin_NYC]

Thank you for your reply, I later find the way write the JSON response.

The way to solve it is add a valid JSON string, for example:

{
    success: <%=successFlag%>,
    "invalid" : [{"name":"2222"},{"name":"3333"}]
}

to the server side code. Hopefully someone else find it help...