I've seen in OData documentation that there are Edm types Date and Time. Currently in my database there are many DATE fields being represented in EF as DateTimes, so the ODataConventionModelBuilder is declaring them as Edm.DateTime. How can I change them to Edm.Date?
Was hoping I could do this:
entityType.Property(p => p.AgreementDate).EdmType = EdmType.Date;
The corresponding Edm type of certain property is mapped from the CLR type and can't be overrided by ODataConventionModelBuilder.
If you want to change the Edm type, you can ignore these properties within the ODataConventionModelBuilder.
After getting the Edm model by calling GetEdmModel on the ODataConventionModelBuilder, you can add these properties with Edm.Date to the Edm model by calling OData APIs.
Here's my answer in case someone is interested in the details of how to implement Feng Zhao's suggestion. I didn't find the API too discoverable, so I wanted to share.
First, build your EDM model as usual with the ODataConventionModelBuilder but ignore the date property:
...
entitType.Ignore(p => p.AgreementDate);
...
IEdmModel model = builder.GetEdmModel();
Then add the date property "manually":
var myType = (EdmStructuredType)model.FindDeclaredType(typeof(MyType).FullName);
var dateType = (IEdmPrimitiveType)model.FindType("Edm.Date");
myType.AddProperty(new EdmStructuralProperty(myType, "AgreementDate", new EdmPrimitiveTypeReference(dateType, false)));
That's it.
Related
I am using Entity Framework code first with a generic repository pattern with ASP.NET MVC. I have two tables Category and Product.
My model class of product is like this
Public class Product
{
public int ProductID{get;set;}
Public int CategoryID{get;set;}
[ForeignKey("CategoryID")]
public virtual Category Category{get;set;}
[NotMapped]
public string CategoryName{get;set;}
}
The model is binding correctly as long as I am getting data using DBContext.
But I am having a problem when I am getting list of products from stored procedure mapped to Product object. So it is not mapping the Category property of Product object and hence I cannot able to get Category.CategoryName.
So I added a new property with [NotMapped] attribute in product class as CategoryName. But it is also not binding from stored procedure.
And if I remove the [NotMapped] attribute then it is correctly binding from stored procedure but error occurs again when getting product by DbContext (Linq).
Please help me in this regards.
You don't need to add an extra property, use the DbSet.SqlQuery method for queries that return entity types. The returned objects must be of the type expected by the DbSet object, and they are automatically tracked by the database context unless you turn tracking off.
var products= _context.Products.SqlQuery("storedProcedureName",params);
The columns returned by SP should match the properties of your entity type otherwise, it will throw an exception.
After execute your SP, you should be able of get the CategoryName through your Category navigation property:
var catName=someProduct.Category.CategoryName;
On the other hand, the returned data by the Database.SqlQuery isn't tracked by the database context, even if you use this method to retrieve entity types. If you want to track the entities that you get after execute your SP using this method, you can try this:
//Attach the entity to the DbContext
_context.Product.Attach(someProduct);
//The Category navigation property will be lazy loaded
var catName=someProduct.Category.CategoryName;
If you have disabled lazy loading you can load explicitly your navigation property:
//Load the Category navigation property explicitly
_context.Entry(someProduct).Reference(c => c.Category).Load();
I have a situation in AutoMapper where I need to create a mapping with an interface destination. This is not a problem, and when using the normal Mapper.Map, it returns a proxy class as expected. However, when I try to do something similar with .Project().To(), which I need to use because an ORM is involved, I have issues. Here is the exact code that is failing which I replicated in a unit test:
AutoMapper.Mapper.CreateMap<RoleDto, IRole>(); //both just have Id/Name
IQueryable<RoleDto> roleDtos = new List<RoleDto>
{
new RoleDto { Id = 1, Name = "Role1" },
new RoleDto { Id = 2, Name = "Role2" }
}.AsQueryable();
//this works:
List<IRole> roles = roleDtos.Select(
roleDto => AutoMapper.Mapper.Map<IRole>(roleDto)
).ToList();
//this does not work:
List<IRole> roles2 = roleDtos.Project().To<IRole>().ToList();
I'm getting ArgumentException:
ArgumentException: Type 'UnitTestProject5.IRole' does not have a default constructor
In my real implementation the .Select is being performed on an Entity Framework collection, which is why I need to stick with .Project().To().
I have no issues with .Project().To() if the destination is not an interface. Additionally, I have no issues with the interface destination if I use .Map().
How can I get the interface destination and .Project.To() to work at the same time? Why is .Project.To() not giving me proxy classes like .Map() is? Any ideas?
Thanks!
Mapper.Map() takes the linq-to-objects route to materialize objects. As you said, AutoMapper is capable of creating types on the fly if the mapped target is an interface.
Project().To() is a way to translate the whole query, including the mapping, into SQL. Which is great, because only the properties that are required for the target object are included in the SQL query. However, the things AutoMapper does for creating types on the fly (undoubtedly some Refection voodoo) can never be part of an expression tree that can be converted into SQL. That's why Project.To simply tries to new up an object, even if it's an interface.
You'll have to use a concrete type as a mapping target. Of course, this type can implement an interface, so you can keep the independence you want.
I've got a class called Customer that has several properties, i.e. FirstName, LastName, City, State
The Customer class has some data annotations to fix naming and other things. (This class is being used as a model for MVC)
I've got a Linq query against an EF5 entity that has those same fields. Is there a simple way to map the query results to the class other than:
customer.FirstName = item.FirstName;
customer.LastName = item.LastName;
customer.City = item.City;
etc.....
I have run across references to automapper (and others) but was wondering of there are other options based on the identical nature of the results and class?
If you are creating the objects at that time, using object initalizers is probably the cleanest coded solution.
var model = new myMvcModel()
{
FirstName = input.FirstName,
LastName = input.LastName,
City = input.City
}
Otherwise using reflection or AutoMapper as Ek0nomik suggest are your only solutions that I could suggest.
Like Ek0nomik I prefer to do it manually rather than AutoMapper. Even created a VS macro to inspect both objects and output some scaffolding.
My team is using Entity Framework 4.3.0 - Code Only with POCO classes as our ORM. Right now we use DBSets of Classes to access our 'tables'
Public Property Customers As DbSet(Of Customers)
But often we are doing soft deletes based on a IsDeleted column in LINQ, and filtering our select statements accordingly:
Dim LiveCustomers =
From C In EM.Customers
Where C.DeleteFlag = False
What I would really like to do is, instead of writing every query to include this filter, create some lower level property (possibly at our inherited DbContext level) that provides the filtered set, while maintaining strong type.
I tried this:
Public Property Customers As DbSet(Of Customer)
Public Property Customers_Live As DbSet(Of Customer)
Get
Return From C In Customers
Where C.DeleteFlag = False
End Get
Set(value As DbSet(Of Customer))
Customers = value
End Set
End Property
However that yielded me this error:
Multiple object sets per type are not supported. The object sets 'Customers' and 'Customers_Live' can both contain instances of type '__.Customer'.
A quick check on google yielded this promising result (How to: Query Objects with Multiple Entity Sets per Type) But after updating my Connection String, I'm still getting the same error.
<add name="EntityManager"
providerName="System.Data.SqlClient"
connectionString="
Data Source=xxxxxx;
Initial Catalog=xxxxxx;
User Id=xxxxxx;
Password=xxxxxx;
MultipleActiveResultSets=True"/>
So my question is, how could I effectively create a LINQ view that allows me to apply filtering, without impacting the upstream usage too drastically?
Change your property like this:
Public Property Customers As DbSet(Of Customer)
Public Property Customers_Live As IQueryable(Of Customer)
Get
Return From C In Customers
Where C.DeleteFlag = False
End Get
End Property
This is slightly different, as you won't have things like Add() or Remove(), but for a view you typically wouldn't expect to have that kind of functionality. If you want to add a new one, or remove one you should use the normal Customers property.
You could have your POCO classes inherit from a new class that has a new method that would do the filtering for you. Add something like this to the new class
--PSEUDO CODE!--
Public Function Filtered() as IEnumerable(Of Out T)
Return (From x In Me Where x.DeleteFlag).ToList()
End Function
and you could call it like:
Dim LiveCustomers =
From C In EM.Customers.Filtered
Or you could create an Interface and do a dependancy injection when you call your linq query. You'll have to google that one :)
First of all, I am new to ASP.Net MVC 3, and I am also using EF 4.1.
I have a complex object, something similar to let's say a Product object containing a Category object. So we have Product.CategoryId, Product.Category and some extra properties. I also have a form to create products with a dropdown list to select the category.
In my controller, after the product has been created, I need to have access to some property of the Category to perform some extra stuff. However, although Product.CategoryId is set, I cannot access Product.Category.SomeProperty because Product.Category is null. I expected Product.Category would be loaded automatically using some lazy loading, but it does not seem to be.
The code in my Controller looks like this:
[HttpPost]
public ActionResult Create(Product product)
{
if (ModelState.IsValid)
{
db.Products.Add(product);
db.SaveChanges();
string someString = product.Category.SomeProperty;
...
Now, this does not work because product.Category is null. What do I need to add so that I can access SomeProperty?
Lazy loading will not work in this scenario because you are adding a new object. Lazy loading will work on "Proxy" entities created by EF context.
So what you can do here is explicitly load the navigational property.
db.Products.Add(product);
db.SaveChanges();
db.Entry(product).Reference(p => p.Category).Load();
string someString = product.Category.SomeProperty;
Lazy loading doesn't work in your case because the product which is passed in into the controller action is not a proxy object but created as an ordinary Product instance by the model binder.
What you expect would work if product is created as a proxy:
var product = db.Products.Create();
product.CategoryId = 1;
db.Products.Add(product);
db.SaveChanges();
string someString = product.Category.SomeProperty;
// Category gets lazily loaded now
The Category property on the Product class must be virtual of course to have lazy loading working at all.
It doesn't help you in your situation because the model binder doesn't create a proxy.
Solutions: Either explicite loading (see #Eranga's answer) or in case you really only need to inspect the SomeProperty of the category fetch the value in a projection:
string someString = db.Entry(product).Reference(p => p.Category).Query()
.Select(c => c.SomeProperty).SingleOrDefault();
...or (because you have the key of the category)...
string someString = db.Categories.Where(c => c.Id == product.CategoryId)
.Select(c => c.SomeProperty).SingleOrDefault();
You may need to explicitly enable lazy loading in your entity framework object context, as described in the MSDN article How to: Use Lazy Loading to Load Related Objects
In the Entity Framework runtime, the default value of the
LazyLoadingEnabled property in an instance of ObjectContext is false.
db.ContextOptions.LazyLoadingEnabled = true;
More detail is provided in the Loading Related Objects article, just look in the section labeled "Lazily Loading Entity Objects".