I am new to using the ADO.NET Entity Data Model tool. I have a table in my database that has three properties (FirstName, LastName, Age). I need to add a field to this entity called IsChosen. However, I cannot add this column in the database.
How do I add custom properties to entities generated through this tool?
Thank you!
The Entity Data Model tool creates partial classes.
You can extend those partial classes in another source file. You just need to make sure your section of the partial class lives in the same namespace as the Entity Data Model generated classes. For example:
Tool Generated Code
namespace Your.Generated.Classes
{
public partial class Stuff
{
public string Name {get; set;}
public int Age {get; set;}
}
}
Your Seperate Code File
namespace Your.Generated.Classes
{
public partial class Stuff
{
public string NonDatabaseProperty {get; set;}
}
}
Related
I am using database first approach. I already mapped my tables and have generated entities. In my edmx model I have changed table names so that my entity names are more readable. But now for some reason I need to get original table/column name for my entities. Is there anyway in which I can update tt file to get table/column names? (See desired code below).
// Current generated code for entity,
public partial class University
{
public int DepartmentCount { get; set; }
}
// Desired code for entity,
[Description("TABLE_UNIVERSITY")]
public partial class University
{
[Description("DEPARTMENT_COUNT")]
public int DepartmentCount { get; set; }
}
I'm using Entity Framework edmx. When I update the edmx I lose my metadata.How do you create and use metadata properties (that are not real fields).
Create a Metadata folder in the project where is the edmx. Create a class with the name of your entity as bellow: And within the same file create another class with the name of your entity with the "metadata" extension (MyEntityMetadata).
namespace MyNameSpace.DataAccess //You need to use the same namespace of edmx entities files
{
[MetadataType(typeof(MyEntityMetaData))]
public partial class MyEntity //This is possible because entities files using partial class
{
[NotMapped] //System.ComponentModel.DataAnnotations.Schema
public int MyProperty { get; set; }
//more properties...
}
public class UsuarioMetaData
{
[Display(ResourceType = typeof(Resources.Global), Name = "MyFieldLabel")]
public int MyField { get; set; }
//More fields
}
}
I am trying to generate a CMS using the Entity Framework Code First. I have a TextBox class that I'd like to have a System.Drawing.Font property or a Dictionary Property. Can the Entity Framework Code First generate properly for System.Drawing.Font or Dictionaries?
EF CF is a code-based ORM (Object-Relational Mapper). It handles the storage and retrieval of data held in classes in your app to and from tables in a database.
If you want to store/retrieve data from your forms, you should create "model" classes - these are just simple classes that contain properties for the values you want to store in your DB. For example:
public class Page
{
public Guid ID {get; set;}
public string Title {get; set;}
public string Body {get; set;}
public string FontName {get; set;}
public int FontSize {get; set;}
}
You then create a DbContext class that contains DbSet instances of the type of your model classes:
public class StorageContext : DbContext
{
public DbSet<Page> Pages {get; set;}
}
Now, EF will figure out the structure of the data you want to store and handle all the DB operations to load/store your data to your DB.
You should be able to write pretty much all your model and DB code (in a separate library in case you need to reuse).
Note: I also strongly encourage you to add an additional level of abstraction and create a Repository class so that your UI code needs know nothing about HOW you're storing your data - this will allow you to change to a completely different storage engine later without having to touch your app code! For example:
public class PageRepo
{
StorageContext _ctx = new StorageContext();
public Page GetPageById(Guid id)
{
...
}
public void StorePage(Page page)
{
...
}
}
You then use your StorageContext (or, better still, your repository) and Model classes to get/store data from/to your DB and copy those values into the necessary fields in your forms, peprforming any data validation before you store data, of course ;)
HTH.
Entity framework allows you to only map few predefined types. That is because it is an ORM and data types that are common to many RDBMS are supported. You can how ever break the complex type such as Font to its primitive properties and map to an entity.
Eg
public class Style
{
public Guid ID {get; set;}
public string FontName {get; set;}
public int FontSize {get; set;}
// other properties
}
In your UI layer you would have a TextBox that will use the style to build a Font.
public class TextBox
{
public TextBox(Style style)
{
Style = style;
}
protected Style Style {get; set;}
public Font FontSize { get { return new Font(Style.FontName, Style.FontSize); } }
// other properties
}
I am writing an mvc3 application with Entity. I am brand new to .net and entity, so this question may be basic.
I have a model in that represents an object that gets saved to the database. But I would like to have an extra field display on the create and edit forms that is not saved to the database.
Is there a way to specify that a field is not saved with the rest of the object? Also, is there a way to make a field required on create and not on edit?
I would just hard code it, but I would like to include it in the validation that can be set on the entity models.
I am using Entity code first.
you can use viewmodels for displaying or editing, while saving map your view model to domain model(excluding the non-desired fields) and then save it. You can use a tool auto mapper to map your view models to domain models.
say for example you have a domain class person
public class Person
{
public string Name {get; set;}
public string Address {get; set;}
}
then you make a view model
public class VMPerson
{
public string Name {get; set;}
public string Address {get; set;}
public int Age{get;set;}
}
fetch data into your view model and pass it to your view the query may look like
var q = (from p in db.Person
select new VMPerson{
Name = p.name,
Address = p.address,
Age = 16
}).SingleOrDefault();
return q;
in your view the age will also be displayed, then on post
[HttpPost]
public ActionResult Person(VMPerson vmperson)
{
Person p = new Person()// your domain object
// mapping part here
p.name = vmperson.name;
p.address = vmperson;
TryUpdateModel(p);
db.Person.Save();
}
Using MVC3 and Entity Framework.
Am trying to get validation flowing from data model
Question: On an entity framework save, how can I automatically put in the [MetadataType tag below for my buddy class?
[EdmEntityTypeAttribute(NamespaceName="ModelValidationTestModel", Name="Person")]
[Serializable()]
[DataContractAttribute(IsReference=true)]
[MetadataType(typeof(Person_Validation))] // I want EF to put this line in automatically
public partial class Person : EntityObject
...
[Bind(Exclude="PersonID")]
public class Person_Validation
{
[Required]
public string FirstName { get; set; }
[Required]
public string LastName { get; set; }
[Required]
public int Age { get; set; }
[Required]
public string Email { get; set; }
}
Using example from: http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx
I think the best option is not to mess with the class generated by EF. Instead define your own partial class:
[MetadataType(typeof(Person_Validation))]
public partial class Person
{
//rest of class may be empty
}
You can do this in the same file as the Person_Validation class if you like.
It's not automatic, but it is safe (your changes won't get lost). This approach will work with any code generation framework (that uses partial classes), not just EF.
Data Annotations/attributes are baked at compile time and you cannot add them dynamically. I would recommend you to avoid passing/getting your EF models to/from the views. You should be using view models which are classes specifically tailored to the needs of a given view. It is those view models that will handle the would handle view specific validations such required, format, ...). You could then use AutoMapper to have your controller map between your view models and the EF models.