Is there a way to change the pattern that EF uses to generate the Entity name when generating the EDM model from an existing database?
Example:
I have a table: table_name and I want my entity to be named TableName without me having to change it manually.
EDIT: I know I can change the POCO generation template, but how about the EDM generation? Is this done with a template as well? If so, where is this template located?
I'm affraid it is not possible - at least not without investigating possibilities of EF Designer extensibility or investigating EdmGen internals. The point of Entity designer is to allow you easily map / change those names.
Interestingly it is possible if you start with model (EF designer) and want to generate database from the model - in such case the process is controlled by workflow and T4 templates and you can change it but in case of generating model from database the process is most probably hardcoded inside Edmgen tool - you can check if this tool has any API which would allow you changing the behavior.
Anyway EDMX is just XML so if you have exact pattern you need to replace you can create very simple tool, transformation or script which will modify your EDMX file after generation from the database.
You cannot change the POCO T4 template. The template must produce classes with exactly same names as you have for entities in your model. Otherwise the POCO magic will not work.
Related
I have been working with Entity Framework 4 and SQL Server. The main problem I have found is that the table names in the database are all lower case and has underscore. This means that when I create the entities in Visual Studio, the classes and the properties are all lower case with underscores Is there any way to achieve Pascal Casing for the classes created and Camel Casing for the Properties?
Eg:
table_name--> to be converted as TableName
Is there any other templates need to be added or any other way to achieve this.
Editing the class name and properties manually in is not recommended as i have huge number of entities
Why not use a T4 template to generate the entity classes? That way, you can add a method to convert the table names to the convention of your choice.
VS comes with a couple of built-in T4 templates for EF, so it's very likely that you can just pick one of these and modify it. I wouldn't recommend writing your own from scratch!
If you haven't used T4 templates before, a quick start is to open your EF model in the designer, right-click a blank part of the design surface and choose "Add Code Generation Item." This will open a dialog with the installed T4 templates for EF, and you can choose whichever you feel most appropriate.
You can then right-click the T4 template files in Solution Explorer (it will have a .tt extension) and choose "Run Custom Tool" to generate the entities themselves. You can edit the .tt file (it's just a plain text file, containing something that looks horribly like VBScript!) and make the modifications. Then run the custom tool again and see if the generated entities have the right names.
Hope this helps.
The following blog post has a great response on how to do this. It involves modifying the T4 template file created when creating the data model.
http://khalidk7.wordpress.com/2014/04/21/entity-framework-ef-t4-template-modification-to-output-pascalcasing-database-objects/
I'm starting a new application that must use an existing database that use some naming conventions that are really annoying in .net (table names start with several trigrams that specify the business domain of the table, column names start with the tables trigram, trigrams are in uppercase and separated by underscores, etc.,).
What I'd like to do is to write a simple renaming rule (this is as simple as finding the last underscore and take everything after that) and apply it in Entity Framework. I don't really want to edit the names one by one in the editor, especially because the database might change and I don't want to do it several times.
I'm using Database First (as the database already exists and it is "the master"), and EF 4.x DbContext Generator and it works really great out of the box (with badly named classes and properties though).
I edited the T4 templates in order to rename the generated entities and properties, but when I try to perform any request, the DbContext object can't find the table that matches with the entity I'm trying to request and I get this exception :
The entity type [Entity Name] is not part of the model for the
current context.
This is obvious why it doesn't find the table : nothing tells it how to match the entity name and the table as I changed it on the fly.
I read that I can add instructions in the OnModelCreating(DbModelBuilder modelBuilder) method but this is not used in Database First (and the default T4 template adds an exception in it, just in case).
So now I'm stuck, I don't know how to specify that matching.
Here are several ideas I have but not sure if it's correct or doable :
Using the "plural / singular" API to change the name of the Entity ? Sounds like a dirty workaround. But it might work (didn't try though).
Finding a way to edit the EDMX file on the fly.
Editing the EDMX afterwards but it might complicate the process (edit in the designer, then execute a tool to alter the EDMX, then run custom tool to regenerate entities and DbContext... while today I just have to edit in the designer).
Using Code First (as it seems easier to use different entity names than table names, through attributes or instructions in the DbContext class), but it sounds like it would not be more complicated to use it with an existing database.
Any idea ? Or did I miss something ?
You won't be able to use a T4 transform for this, as you want to change the content of the actual .edmx file to map your store entity names (with the obnoxious prefixes) to your sanitized conceptual entity names.
Instead, you're better off writing an application that takes an .edmx file as input and sanitizes the names under the conceptual model tag and modifies the mapping names to reflect the sanitized names. I understand that this is your third option and that you wanted to avoid this if possible, but this is the most straightforward way to go about it. Bear in mind that you'll only have to run this tool when you add new tables or columns.
Now that i have generated 19 code-first classes from an existing database by:
Creating a Model-First Entity, and choosing "Generate from database"
Right clicking and choosing "Add Code Generation Item"
EF 4.x DbContext Generater
All the classes i want are generated, and I'm very happy with them...
And now for my question(s)
Why are they all the generated .cs files nested in a sealed .tt collection?
Why can't i copy paste them out to any folder i like, and treat them like normal classes?
Is it just me, or are you unable to use migrations "update-database" when you do it like that?
I guess my overall question is, why are they located in a .tt folder?
And how shall i update my database now? By editing the database manually and then update the Model, and then generate the dbContext again? Or is there a trick to get .cs files out of a .tt folder?
How do you modify you database after generating your DbContext?
Why are they all the generated .cs files nested in a sealed .tt collection?
Your code-first classes are not code-first classes. They were generated based on your database schema. Hence, this is a database-first approach. With database first, your entity classes are generated based on the database. In other words, the database comes first, the code comes second. The .tt file is a T4 template that decides how to generate your classes based on the database. You could change the database and then regenerate your entity classes.
Why can't i copy paste them out to any folder i like, and treat them like normal classes?
Because they are generated files, based on the T4 template.
Is it just me, or are you unable to use migrations "update-database" when you do it like that?
This part of your question I can't answer for certain, and will have to defer. However it seems to me like you want to mix and match approaches. It sounds like you want to start by generating code classes based on your database, and from there forward, change the database based on new entity classes you add to the model project. Is that right?
You can forgo the code-generation part and just go with a pure code-first approach, now that you have an idea of what the entity POCO's should look like. I have tried this T4 code generation before (pre EF 4.1) and immediately abandoned it, because as you have seen, since the entity and DbContext classes are generated, you lose control over the object-oriented model.
In C# is it possible to create a model of entities regardless of the database initially. Are there tools to create graphic entities in this way? What do you recommend?
Well, it's in your question as a tag - entity framework is a good tool for this. You can create classes, that you push later to the database.
Search for "code-first". Google will provide plenty of results I'm sure.
Edit based on the comment:
Well, in that case, try this: when you're creating edmx file, pick the second option - empty model.
From its description:
Creates an empty model as a starting point for visually designing a
conceptual model from the toolbox. Classes are generated from the
model when the project is compiled. You can specify a database
connection later to map the conceptual model to the storage model.
this may be the thing you want then.
As a part of our application architecture, we like to define clear lines between our functional layers. A typical application solution, therefore, will contain:
Entity
Model
Task
Presenter
FrontEnd
These end up being completely distinct assemblies.
The Entity/Model delineation is done to keep database access functionality in a separate layer from our POCOs, so that only Task ever need know about Model, while everyone up to Presenter knows about Entity
This works well when using Code-First or Fluent-API - but due to the lack of support for SPROCs in those paradigms, it turns out that under EF 4.1 I must use EDMX models.
So - I'm generating POCOs using a DbContext Generator, but the resulting classes end up under .Model, and while I can force their namespace into .Entity instead, they still live in the .Model assembly, which means now .Presenter must reference .Model to get to classes that should be in .Entity.
Is there a way to force or trick EF to dump its generated output into a different Project?
Sure. DbContext Generator are just two T4 templates. You can move the template generating entities to other project. You just need to modify template to point to correct EDMX file. This is default:
string inputFile = #"Model.edmx";
You must change it to relative address to your EDMX file. It will be something like:
string inputFile = #"../Model/Model.edmx"
The template will automatically use default namespace of current project for generated entities but you will have to modify the second template for context to use the new namespace so that entity types are correctly resolved from referenced assembly.
There is small disadvantage of using template in another project - it will not update automatically when you modify model. You must always trigger entity recreation manually by using Run custom tool from context menu on template file.