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Dec 16

Written by: Michael Washington
12/16/2012 9:51 AM 

In the Visual Studio LightSwitch HTML Client, extra steps are required to determine who the currently logged in user is.

The first step is to turn on authentication in the LightSwitch project.

We create a UserName field. Notice that it is Required. This is the thing that will cause a problem (demonstrated later).

We select the Entity (table), then we select Write Code, then the Inserting method.

We use the following code for the method:

 

        partial void PromiseOrdersSet_Inserting(PromiseOrders entity)
        {
            // Set the Username 
            entity.UserName = this.Application.User.Name;
        }

 

We also set the updating method:

 

        partial void PromiseOrdersSet_Updating(PromiseOrders entity)
        {
            // Set the Username 
            entity.UserName = this.Application.User.Name;
        }

 

We need to do this to protect the OData service points. Only setting this on the client side code (shown later) is not enough.

A user could access the OData service point directly and alter the value. Using the code above prevents this.

However, the UserName is not populated when we run the application.

To fix this, we first switch to File View.

We add a page to the Server project using the following code:

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace LightSwitchApplication.Web
{
    public class GetUserName : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            using (var serverContext = ServerApplicationContext.CreateContext())
            {
                context.Response.ContentType = "text/plain";
                context.Response.Write(serverContext.Application.User.Name);
            }
        }
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

 

(this code uses the new serverContext API)

 

We switch back to Logical View, select the Entity, Client (tab), Write Code, and then the created method.

We add the following code:

 

myapp.PromiseOrders.created = function (entity) {
    // Set the default date for the Order
    entity.OrderDate = new Date();
    // Using a Promise object we can call the CallGetUserName function
    msls.promiseOperation(CallGetUserName).then(function PromiseSuccess(PromiseResult) {
        // Set the result of the CallGetUserName function to the 
        // UserName of the entity
        entity.UserName = PromiseResult;
    });
};
// This function will be wrapped in a Promise object
function CallGetUserName(operation) {
    $.ajax({
        type: 'post',
        data: {},
        url: '../web/GetUserName.ashx',
        success: operation.code(function AjaxSuccess(AjaxResult) {
            operation.complete(AjaxResult);
        })
    });
}

 

We run the project:

The UserName is now retrieved.

 

LightSwitch Help Website Articles

Writing JavaScript That Implements The Binding Pattern In Visual Studio LightSwitch

Implementing The Wijmo Radial Gauge In The LightSwitch HTML Client

Writing JavaScript In LightSwitch HTML Client Preview

Creating JavaScript Using TypeScript in Visual Studio LightSwitch

Theming Your LightSwitch Website Using JQuery ThemeRoller

Using Toastr with Visual Studio LightSwitch HTML Client (Preview)

 

LightSwitch Team HTML and JavaScript Articles

Custom Controls and Data Binding in the LightSwitch HTML Client (Joe Binder)

Creating Screens with the LightSwitch HTML Client (Joe Binder)

The LightSwitch HTML Client: An Architectural Overview (Stephen Provine)

Writing JavaScript Code in LightSwitch (Joe Binder)

New LightSwitch HTML Client APIs (Stephen Provine)

A New API for LightSwitch Server Interaction: The ServerApplicationContext

Building a LightSwitch HTML Client: eBay Daily Deals (Andy Kung)

 

Download Code

The LightSwitch project is available at http://lightswitchhelpwebsite.com/Downloads.aspx

(you must have HTML Client Preview 2 or higher installed to run the code)