Redirecting to Web API after form submission.

I am uploading an image. This is the code of my view:

Code:

Ext.define('MyApp.view.AddCountry', {
    extend: 'Ext.window.Window',
    alias: 'widget.addcountry',
    closable: true,
    closeAction: 'destroy',
    modal: true,
    height: '28%',
    width: '45%',
    panelStatus: 'add',
    panelId: 0,
    initComponent: function () {
        var me = this;
        me.items = [{
            xtype: 'form',
            headers: { 'Content-Type': 'text/html' },
            standardSubmit: true,
            layout: 'form',
            bodyPadding: '5 5 0',
            itemId: 'addCountryForm',
            frame: false,
            items: [{
                xtype: 'textfield',
                fieldLabel: 'Name',
                maxLength: 25,
                enforceMaxLength: true,
                allowBlank: false,
                name: 'Matrix'
            }, {
                xtype: 'textfield',
                fieldLabel: 'Description',
                maxLength: 100,
                enforceMaxLength: true,
                allowBlank: false,
                name: 'description'
            }, {
                xtype: 'filefield',
                name: 'flagImage',
                fieldLabel: 'Flag',
                buttonText: 'Select Image...'
            }],
            buttons: [{
                text: 'Save',
                itemId: 'btnSaveCountry'
            }, {
                text: 'Cancel',
                itemId: 'btnCancelAdding'
            }]
        }];
        this.callParent();
    }
});

This is the upload code in my controller:

Code:

SaveWidgetType: function (button) {
        var form = button.up('form').getForm();
        form.submit({
            url: 'localhost/myapp/api/country/addcountry',
            waitMsg: 'Please wait...',
            success: function (f, o) {
                Ext.Msg.alert('Success', o.result.result);
            },
            failure: function (f, o) {
                Ext.Msg.alert('Error', o.result.error);
            }
        });
    }

When I submit the form, it gets redirected to "localhost/myapp/api/country/addcountry" that shows this string:

{"$id":"1","success":true,"result":"Uploaded Successfully.","error":null}Can someone point out the error? If I remove "standardSubmit: true", The wait message keeps rendering. The control gets stuck there.