[.NET] I don't have time for this. POCO Generator, Function Imports, Returning None

1. Used POCO Generator to create Function Imports
2. Had a Function that returns none
3. POCO Generator does not generate Functions that return none.

WUDDDAAAPPPAAAACCCKKERRRR

Alright, this was such a headache, but thanks to Matt Johnson in this stack overflow link:
http://stackoverflow.com/questions/3797248/update-function-import-not-displaying-in-context-file

...problem was solved.

Here is the Function Import region of the .tt file:


region.Begin("Function Imports");

        foreach (EdmFunction edmFunction in container.FunctionImports)
        {
            var parameters = FunctionImportParameter.Create(edmFunction.Parameters, code, ef);
            string paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
            string returnTypeElement = edmFunction.ReturnParameter == null
? null : code.Escape(ef.GetElementType(edmFunction.ReturnParameter.TypeUsage));

#>
    <#=Accessibility.ForMethod(edmFunction)#> <#= returnTypeElement == null ? "int" : ("ObjectResult<" + returnTypeElement + ">") #>  <#=code.Escape(edmFunction)#>(<#=paramList#>)
    {
<#
            foreach (var parameter in parameters)
            {
                if (!parameter.NeedsLocalVariable)
                {
                    continue;
                }
#>

        ObjectParameter <#=parameter.LocalVariableName#>;

        if (<#=parameter.IsNullableOfT ? parameter.FunctionParameterName + ".HasValue" : parameter.FunctionParameterName + " != null"#>)
        {
            <#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", <#=parameter.FunctionParameterName#>);
        }
        else
        {
            <#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", typeof(<#=parameter.RawClrTypeName#>));
        }
<#
            }
#>
        return base.ExecuteFunction<#= returnTypeElement == null ? "" : ("<" + returnTypeElement + ">")#>("<#=edmFunction.Name#>"<#=code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()))#>);
    }
<#
        }

        region.End();

[.NET] Updating Detached Objects in Entity Framework

Here's the scenario.

An object is being passed like this

1. Object gets pull from the database through the Business Logic layer and WCF, as well as getting converted into a detached object.
2. Values are changed in the Business Logic Layer.
3. Object gets passed back into the WCF for an update.

I've seen several ways of how a detached object could be updated. Previously in the data access layer, I was retrieving the original object from the database and getting the object again by the original's entity key. Then updated the values and applied the changes. It looks something like this:

using (MyDBContext db = new MyDBContext ())

                {

                    My_Object obj =  db.GetObjectByKey(GetObjectFromDatabaseByID(id).EntityKey) as My_Object;

                    obj.Name = <newName>;

                    if (obj != null)

                    {

                        db.ApplyCurrentValues("My_Object_Table_Name", obj);

                        db.SaveChanges();

                        return "Succesfully Updated!";

                    }

                    else

                        return "Record Does Not Exist.";

                }

So one thing, the method that surrounds this code is only passing an 'id'. There is no objects coming in. Therefore, the object would have to be retrieved again to use its Entity Key to grab the object again, except with an attached state. Another parameter that was passed into the method was the newName. So this newName variable has to be assigned to the new attached object. Only then, we can apply and save the changes. Yes, this is a crude way of doing it, but it works.

Recently, I found a new way of handling an update. So what if we pass in a whole object? Will we have to consider the change of all members of the object? What if the object has 50 members? Well, coding will definitely suck. This method was posted on MSDN, so I'm just going to take it as a valid strategy, and it goes something like this:

 EntityKey key = default(EntityKey);

                object originalObj = null;

                using (MESDataModel.e_MESEntities db = new MESDataModel.e_MESEntities())

                {

                    key = db.CreateEntityKey("KIT_Part", ct);

                    if (db.TryGetObjectByKey(key, out originalObj))

                    {

                        db.ApplyCurrentValues(key.EntitySetName, ct);

                        db.SaveChanges();

                        return "Succesfully Updated!";

                    }

                    else

                    {

                        return "Record Does Not Exist.";

                    }

                }

In this situation, we are creating an entity key out of the passed in object. If it already has a key, then it will return the original instead of creating a new one. Similar to the first method, we are using the key to retrieve an attached object. At this point, the attached object and the passed in object now has the same keys. Call ApplyCurrentValues and the data from the passed in object will write to the attached object within context. This is pretty much MSDN's definition of what ApplyCurrentValues does. Save changes and everything should work. Hope this kind of helps.

Hmm, Okay, what about using DetectChanges?
This method seems to be good, if you are pulling straight from the database, writing new values, and saving it back to the database. No detached objects involved here. If there is a way to use this method with cross platform in mind (Android, iPhone), please let me know.

[SQL/MySQL/.NET] Setting databases for .NET usage

After setting up WCF services and having my android devices consuming it, I wanted my WCF to be the layer that communicates to a database resource. At first, I had a hard time with getting started with SQL Server, so I went with MySQL instead.

NOTE: In your IIS, make sure the ASP.NET 4.0 Application Pool "Identity" is set to Local System. This is the reason why SQL Server wouldn't go so smooth at first, but I will discuss details later.

MySQL setup:

1. Download MySQL server installer, MySQL OBDC connector, and MySQL Net connector. Optionally, download the Workbench, which provides a GUI solution for handling SQL functions. If you're lame like me, you would use this tool.

2. Set up your tables using Workbench or commandline.

3. In Visual Studio, add a new ADO.NET Entity Data Model and point to your MySQL Server when prompted. If you don't know the server name or IP Addy, you can always go to the Workbench and see the properties there. Mine was 127.0.0.1. Follow through with creating the .edmx file.

4. Now you should see the newly created entities right in front of you. The name of the object is exactly what the header of the entity is. So you can instantiate it like:

User objUser = new User();

Of course, we don't want to instantiate like this, but rather grab the info from the database and create the object then. We will use LINQ to do so.

 Now look for Entity Container Name in the properties of your .edmx file. This is the object you use to connect to the database. So lets just put 2 and 2 together with the entity object included:

MyDBEntities db = new MyDBEntities();
List<User> users = ( from p in db.Users select p ).ToList();

This should select all users from a "Users" table and return it as a list of User objects.

Run the WCF Test Client and test if it works.

SQL Server setup:

Okay, if you installed SQL Server 2008, I believe that it should've created an instance of SQLEXPRESS. So we will just go with this default setup, although, you might have set up another instance, you'll just have to remember the server name for that one.

So by default, your instance of SQLEXPRESS should be your <computername>\SQLEXPRESS. (ex. KETTLEPOT-PC\SQLEXPRESS).

Create tables in SQL Management Studio (Free) by using the server name.

From now on, follow step 3 from the MySQL setup section to configure everything in VS2010.

 Now, if you're getting the "underlying provider" error when you run the WCF Test Client and invoke your method, check out the "NOTE" at the beginning of this post.

Hope that helps!!!!