Consider this class used for DB mapping.
[Bind()]
public class ActiveType
{
[Key()]
public int ID { get; set; }
[Display(Name = "Navn")]
public string Name
{
get;
set;
}
public string Prefix { get; set; }
public string Suffix { get; set; }
}
As you can see, I tried to use the Display annotation to make MVC use that name when it auto-generates entity-framework CRUD pages. However, it ignores it. How do I change this? Is it possible through annotations?
If you are genarating your domain classes it will remove the attributes you have added.
It seems like you are using the domain object in entity framework layer for the model in MVC layer. This is not a good practice. You need to create separate view models (http://blogs.msdn.com/b/simonince/archive/2010/01/26/view-models-in-asp-net-mvc.aspx) for the MVC layer. Because you need to separate the presentation logic from the data layer.
You can use something like AutoMapper to map domain object to view model. http://sourceforge.net/projects/automapper-dn/
The example I provided actually worked, but not for auto-generated EF pages, where it would ignore it in some cases.
Related
I have created a fairly simply domain model using pocos. I have mapped these to an EF DB context using EntityTypeConfiguration<TEnitityType> classes. This all works fine.
I am now trying to create an OData V4 WebAPI controller endpoint using a ODataConventionModelBuilder and this is where things are coming unstuck. It all works fine until it encounters an association that is not convention based. But I cannot find a way to get the ODataBuilder to pick up the mappings from my EntityTypeConfiguration<TEnitityType> classes.
This leaves my with 2 unpalatable options
Decorate my lovely clean pocos with dirty attributes.
Re-map all the non convention based mappings manually using the ODataBuilder
Not sure if code samples will help but here they are anyway, i have simplified the entities for brevity.
var builder = new ODataConventionModelBuilder();
builder.EntitySet<Item>("Items");
config.MapODataServiceRoute(
routeName: "odata",
routePrefix: "odata",
model: builder.GetEdmModel(),
batchHandler: new DefaultODataBatchHandler((GlobalConfiguration.DefaultServer)));
public class Item
{
public Int32 Id { get; set; }
public Int16 ItemTypeId { get; set; }
public virtual ItemType Type { get; set; }
public virtual ICollection<ItemVersion> Versions { get; set; }
public virtual ICollection<ItemTag> Tags { get; set; }
}
The problem comes when it encounters the ItemTags collection, here is an ItemTag:
public class ItemTag
{
public Int32 ItemId { get; set; }
public string Tag { get; set; }
public Item Item { get; set; }
}
Which you can see is not convention based and I have a configuration class for it as follows:
public class ItemTagConfiguration : EntityTypeConfiguration<ItemTag>
{
public ItemTagConfiguration()
{
HasKey(x => new {x.ItemId, x.Tag});
HasRequired(x => x.Item)
.WithMany(y => y.Tags)
.HasForeignKey(x => x.ItemId);
}
}
Does anyone know of a way that I can use these EntityTypeConfiguration files with an ODataBuilder or web API?
EDIT
If found this page which seems to indicate it might be possible with EF 6 which I am using. What I want to do is this
ODataModelBuilder modelBuilder = new ODataConventionModelBuilder();
modelBuilder.EntitySet<Dbf>("Dbfs");
// modelBuilder.Configurations.Add(new DbfMap()); <---- NO GOOD - Needs Class from DBContext we only have a model builder :(
Microsoft.Data.Edm.IEdmModel model = modelBuilder.GetEdmModel();
config.Routes.MapODataRoute("ODataRoute", "odata", model);
but the builder does not have a Configurations property.
Two things:
I have read multiple sources now that ward against using lazy loading and serialization; which is basically what OData is; (It even uses the system.runtime.serialization.datacontract and datamember attributes)
I have had more success in explicitly loading from context, and defining navigation properties in the modelbuilder for dbContext. I understand you are looking at customized nav properties, but I am fairly sure these are overriden methods useful for the ODataModelBuilder class (that does not assume much and needs less Entity Framework to work). Where you mentioned using EF already, I imagine that is the direction you will work, and if you do not need to alias your model names, you add an entry for each Set, using convention naming.
EntitySet("routePrefixName")
in building the EdmModel, and it wires up the relationships you made using Fluent previously. If you do have to add extraneous items to the underlying model, you should define each class as an EntityType<>(), only setting the key. EdmBuilder can use mild properties and key association to attach to the EF model in the ODataConventionModelBuilder.
I have wrestled and sought for some time, and there does not seem to be a wealth of information on .Net OData v4 floating around, probably due to the whole force datetimeoffset issue.
Hope that helps somewhat
I've seen this that suggest I can build different views based on user:
different json views for the same entity
However in asp web api, one uses a Model class, I can't just add new properties willy-nilly.
So, for example I may have uri:
http://host/api/products/id
Returning the model:
public class Product{
public string Code { get; set; }
public string Description { get; set; }
}
But for another purpose I want to add more information, suppose this is expensive because it joins other data to build the model, or formats the data in a very specific way:
http://host/api/productsspecial/id
Returning the model:
public class ProductSpecial{
public string Code { get; set; }
public string Description { get; set; }
public decimal Price { get; set; } //assume expensive to look up
}
So obviously I have a way to do this, two different controllers, returning different views on the data. My question is, is this OK or is there a better way?
Anyway I could do this for example: http://host/api/products/id?includeprice=true and use that to return the alternative model? And is that a good idea?
I would suggest
GET /host/api/products/{id}?fields=code,description,price
You should avoid complicating your resource URL in the manner you describe. Every possible configuration of values would need a new name: "productsReallySpecial", etc.
The problem with ?includePrice=true is you then have a parameter for every variable you might want to make optional. Your documentation can list the default return values and the available return values.
I am trying to create a RESTful web service that returns a list of products using ASP.NET MVC4 Web API. Here is my controller class
public class ProductController : ApiController
{
public IEnumerable<Product> GetProducts()
{
WebCatalogContext dbcontext = DatabaseConfig.Instance.Context;
List<Product> plist = dbcontext.Products.ToList();
return plist;
}
}
When I run my service and call the following URL from my browser :/api/Product, I get System.Runtime.Serialization.SerializationException. I looked into my plist object and there is no problem with it.
Here is my data model:
[DataContract(Name = "p")]
[Serializable]
public class Product
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[DataMember(Name = "id")]
public int Id { get; set; }
[Required, MaxLength(50)]
[DataMember(Name = "ti")]
public string Title { get; set; }
[Required]
[DataMember(Name = "de")]
public string Description { get; set; }
[Required]
[DataMember(Name = "ph")]
public string PhotoURL { get; set; }
[DataMember(Name = "ca")]
public virtual ProductCategory Category { get; set; }
}
[DataContract(Name="pc")]
[Serializable]
public class ProductCategory
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[DataMember(Name="id")]
public int Id { get; set; }
[DataMember(Name="nm")]
public string Name { get; set; }
}
When I remove the reference to ProductCategory from my Product class, all things work just fine. But, when I include it I get the following exception.
Type 'System.Data.Entity.DynamicProxies.Product_664E9A0AA1F165A26C342B508BFFF1279FD3FE059285225BDA19F407A29A9CAD' with data contract name 'Product_664E9A0AA1F165A26C342B508BFFF1279FD3FE059285225BDA19F407A29A9CAD:http://schemas.datacontract.org/2004/07/System.Data.Entity.DynamicProxies' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.
Any idea about what I am missing?
Regards
Entity Framework has wrapped your POCO with an EF Proxy POCO so it can perform lazy loading - this uses the Virtual attribute to create a 'lazy-loadable' navigation property. I expect that is where the serialization error comes from.
You could make a new class and map the POCO to that - then pass the DTO style class from the controller. I've never returned an EF object directly from the API (I always map to some something else) so I don't know another option.
EF POCO to DTO (data transfer object) is relatively painless if you use a tool like http://valueinjecter.codeplex.com/ or http://automapper.org/
To support Lazy Loading for navigation properties which is declared as virtual, EF will generate the proxies for any models which have navigation properties which leads to this kind of exception.
For very simple application, you can use model from EF as DTOs (if having no navigation properties), but for complex application, you should do separate and differ between DTOs and domain models. It should not be mapping 1:1 between DTO and domain model.
Therefore, in your case, you create more DTO model for Web API layer, it will be fine.
I am starting MVC4 with VS2012. I am also using EF5 with the "Database First" method of creating my classes.
However because the generated glasses can be regenerated I cannot put the Data Annotation details to assist with validation.
I have seen some code snippets that use MetaData and partial classes but I was wondering if anyone knows of a small compilable example that I can look at and pull apart to better understand how the vasious classes interlink.
Many many thanks for any help.
Dave
You can achieve what you need through extending models. Suppose that EF generated the following entity class for you:
namespace YourSolution
{
using System;
using System.Collections.Generic;
public partial class News
{
public int ID { get; set; }
public string Title { get; set; }
public int UserID { get; set; }
public virtual UserProfile User{ get; set; }
}
}
and you want do some work arounds to preserve your you data annotations and attributes. So, follow these steps:
First, add two classes some where (wherever you want, but it's better to be in Models) like the following:
namespace YourSolution
{
[MetadataType(typeof(NewsAttribs))]
public partial class News
{
// leave it empty.
}
public class NewsAttribs
{
// Your attribs will come here.
}
}
then add what properties and attributes you want to the second class - NewsAttribs here. :
public class NewsAttrib
{
[Display(Name = "News title")]
[Required(ErrorMessage = "Please enter the news title.")]
public string Title { get; set; }
// and other properties you want...
}
Notes:
1) The namespace of the generated entity class and your classes must be the same - here YourSolution.
2) your first class must be partial and its name must be the same as EF generated class.
Go through this and your attribs never been lost again ...
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.