I am using repository pattern, so my repository just know about DTOs. It has to query the database with some filters using Entity Framework.
My problem is that Entity Framework only knows about DB model classes, so I have to 'automap' the Expression before being able to use them in any query.
I have declared a method that accepts a Expression as a filter.
public interface IRepository
{
IEnumerable<ItemDTO> GetItemsWithFilter(Expression<Func<ItemDTO, bool>> filter)
{
var filterDb = Mapper.Map<Expression<Func<ItemDB, bool>>>(filter);
return dbContext.CONFIGURATIONS.Where(filterDb).Select(x => Mapper.Map<ItemDTO>(x));
}
}
public class ItemDTO
{
public int numero { get; set; }
public string name { get; set; }
}
public class ItemDB //they are both the same, just for testing purpose
{
public int numero { get; set; }
public string name { get; set; }
}
//failing code
Repository.GetItemsWithFilter(x => x.name=="a");
I followed tutorial that says it is possible to map between expressions but i get some errors:
"The specified type member 'name' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported."}
I solved it by including this extension method call:
Mapper.Initialize(cfg => {
cfg.AddExpressionMapping();
// Rest of your configuration
});
Remeber to install nuget package AutoMapper.Extensions.ExpressionMapping
Install-Package AutoMapper.Extensions.ExpressionMapping
Related
I have the following Entity class definition:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
Notice that table name is different than the class name. I also have a ClientUsers table which is a many-to-many mapping for clients and users. Problem is, when I try to access the webUser.Clients property I get the following exception:
"Invalid object name 'dbo.ClientWebUsers'."
Looks like Entity Framework is trying to guess the name of the third table, but it apparently was not smart enough to take into account the table attribute that I have there. How can I tell EF that it is ClientUsers and not ClientWebUsers? Also what rule does it follow to know which table name comes first and which one comes second in the new table name? I think it's not alphabetical order.
I'm using EF 5.0. Thanks!
From the looks of things you're using Code First, so I'll answer accordingly. If this is incorrect, please let me know.
I believe the convention being used to determine the name of the many-to-many table is determined by the order in which they occur as DbSet properties in your SomeContext : DbContext class.
As for forcing EntityFramework to name your table whatever you like, you can use the Fluent API in the OnModelCreating method of your SomeContext : DbContext class as follows:
public class DatabaseContext : DbContext
{
public DatabaseContext()
: base("SomeDB")
{
}
public DbSet<WebUser> Users { get; set; }
public DbSet<Client> Clients { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<WebUser>().HasMany(c => c.Clients)
.WithMany(p => p.WebUsers).Map(
m =>
{
m.MapLeftKey("ClientId");
m.MapRightKey("UserId");
m.ToTable("ClientUsers");
});
}
}
This assumes your classes are something like the following:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
public class Client
{
public int Id { get; set; }
public ICollection<WebUser> WebUsers { get; set; }
// more properties
}
Finally, here's an integration test (NUnit) demonstrating the functionality working. You may need to drop your database before running it as Code First should want to update/migrate/recreate it.
[TestFixture]
public class Test
{
[Test]
public void UseDB()
{
var db = new DatabaseContext();
db.Users.Add(new WebUser { Clients = new List<Client> { new Client() } });
db.SaveChanges();
var webUser = db.Users.First();
var client = webUser.Clients.FirstOrDefault();
Assert.NotNull(client);
}
}
Edit: Link to relevant documentation for the Fluent API
Rowan's answer (adding here for reference):
Here is the information on how to configure a many-to-many table (including specifying the table name). The code you are after is something like:
modelBuilder.Entity<WebUser>()
.HasMany(u => u.Clients)
.WithMany(c => c.WebUsers)
.Map(m => m.ToTable("ClientUsers");
~Rowan
Is it possible to to use a POCO with generic type and map to Entity Framework Code First? The reason I ask is I get the following error on the context.Products.Add(product); line of the CreateNewProduct() method -
The type 'CodeFirstNewDBConsole.Product`1[CodeFirstNewDBConsole.ProductDetail]' was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive or generic, and does not inherit from EntityObject.
POCO
public class Product<T>
{
public int Id { get; set; }
public string ProductName { get; set; }
public T ProductDetails { get; set; }
}
ProductContext
public class ProductContext : DbContext
{
public DbSet<Product<ProductDetail>> Products { get; set; }
}
Product insert
private static void CreateNewProduct()
{
var productDetail = new ProductDetail { ProductDetailName = "Test Product Detail" };
var product = new Product<ProductDetail>
{
ProductName = "Test Product",
ProductDetails = productDetail
};
using (var context = new ProductContext())
{
context.Products.Add(product);
context.SaveChanges();
}
}
Generic Classes are not supported by Entity Framework. Which is clear from the error message :
"... Verify that the type was defined as a class, is not primitive or generic, and does not inherit from EntityObject."
I am in the process of creating a domain model and would like to have a "BaseEntity" class with an "Id" property (and some other audit tracking stuff). The Id property is the primary key and each Entity in my Domain Model will inherit from the BaseEntity class. Pretty straightforward stuff.....
public class BaseEntity
{
[Key]
public int Id { get; set; }
public DateTime LastUpdate { get; set; }
public string LastUpdateBy { get; set; }
}
public class Location : BaseEntity
{
[Required]
public string Name { get; set; }
public string Description { get; set; }
}
Using the example above, I would like to map the "Id" field to a "LocationId" column. I understand that I can use the modelBuilder to do this for each entity explicitly by doing something like this:
modelBuilder.Entity<Location>().Property(s => s.Id).HasColumnName("LocationId");
But I would like to do this for every Entity in my domain model and it would be ugly.
I tried the following bit of reflection but did not have any luck. For whatever reason, the compiler "cannot resolve symbol type":
foreach (var type in GetTypesInNamespace(Assembly.Load("Domain.Model"),"Domain.Model"))
{
modelBuilder.Entity<type>().Property(x=>x.Id).....
}
Is there a way to define a convention to override the default PrimaryKey convention to map my "Id" property to a "ClassNameId" property in the database? I am using Entity Framework 6.
You should take a look at Custom Code First Conventions. You need EF6 for it to work, but it looks like you're already using it.
Just to give you an overview, take a look at the following convention I've used to convert PascalCase names to underscore names. It includes a convention for id properties... It also includes an optional table name prefix.
public class UnderscoreNamingConvention : IConfigurationConvention<PropertyInfo, PrimitivePropertyConfiguration>,
IConfigurationConvention<Type, ModelConfiguration>
{
public UnderscoreNamingConvention()
{
IdFieldName = "Id";
}
public string TableNamePrefix { get; set; }
public string IdFieldName { get; set; }
public void Apply(PropertyInfo propertyInfo, Func<PrimitivePropertyConfiguration> configuration)
{
var columnName = propertyInfo.Name;
if (propertyInfo.Name == IdFieldName)
columnName = propertyInfo.ReflectedType.Name + IdFieldName;
configuration().ColumnName = ToUnderscore(columnName);
}
public void Apply(Type type, Func<ModelConfiguration> configuration)
{
var entityTypeConfiguration = configuration().Entity(type);
if (entityTypeConfiguration.IsTableNameConfigured) return;
var tableName = ToUnderscore(type.Name);
if (!string.IsNullOrEmpty(TableNamePrefix))
{
tableName = string.Format("{0}_{1}", TableNamePrefix, tableName);
}
entityTypeConfiguration.ToTable(tableName);
}
public static string ToUnderscore(string value)
{
return Regex.Replace(value, "(\\B[A-Z])", "_$1").ToLowerInvariant();
}
}
You use it like this
modelBuilder.Conventions.Add(new UnderscoreNamingConvention { TableNamePrefix = "app" });
EDIT: In your case, the Apply method should be something like this:
public void Apply(PropertyInfo propertyInfo, Func<PrimitivePropertyConfiguration> configuration)
{
if (propertyInfo.Name == "Id")
{
configuration().ColumnName = propertyInfo.ReflectedType.Name + "Id";
}
}
Try this out in your DbContext class;
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Properties<int>()
.Where(p => p.Name.Equals("Id"))
.Configure(c => c.HasColumnName(c.ClrPropertyInfo.ReflectedType.Name + "Id"));
}
int is the CLR Type of my Primary Key fields. I want to refer to all keys in code as Id but DBA's require keys to be Id with Table entity name prefix. Above gives me exactly what I want in my created database.
Entity Framework 6.x is required.
In Entity Framework 6 Code First:
modelBuilder.Entity<roles>().Property(b => b.id).HasColumnName("role_id");
and update-database...
Change in model
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long id { get; set; }
to:
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long role_id { get; set; }
Then remove this:
//modelBuilder.Entity<roles>().Property(b => b.id).HasColumnName("role_id");
A start to the Dynamic approach if NOT using custom conventions
modelBuilder.Entity<Location>().Property(s => s.Id).HasColumnName("LocationId");
You can do this using reflection on the context. Pseudo Code as explanation:
Reflect Context to get a list of POCO names
For each POCO in a dbcontext.
Map Property Id -> string PocoName+Id
Here are the extensions I use for this type of solution.
// DBSet Types is the Generic Types POCO name used for a DBSet
public static List<string> GetModelTypes(this DbContext context) {
var propList = context.GetType().GetProperties();
return GetDbSetTypes(propList);
}
// DBSet Types POCO types as IEnumerable List
public static IEnumerable<Type> GetDbSetPropertyList<T>() where T : DbContext {
return typeof (T).GetProperties().Where(p => p.PropertyType.GetTypeInfo()
.Name.StartsWith("DbSet"))
.Select(propertyInfo => propertyInfo.PropertyType.GetGenericArguments()[0]).ToList();
}
private static List<string> GetDbSetTypes(IEnumerable<PropertyInfo> propList) {
var modelTypeNames = propList.Where(p => p.PropertyType.GetTypeInfo().Name.StartsWith("DbSet"))
.Select(p => p.PropertyType.GenericTypeArguments[0].Name)
.ToList();
return modelTypeNames;
}
private static List<string> GetDbSetNames(IEnumerable<PropertyInfo> propList) {
var modelNames = propList.Where(p => p.PropertyType.GetTypeInfo().Name.StartsWith("DbSet"))
.Select(p => p.Name)
.ToList();
return modelNames;
}
However, you will still need to employee dynamic lambda to finish.
Continue that topic here: Dynamic lambda example with EF scenario
EDIT:
Add link to another question that address the common BAse Config class approach
Abstract domain model base class when using EntityTypeConfiguration<T>
Piggybacking on #Monty0018 's answer but this just need to be updated a little if, like me, you're using Entity Framework 7 and/or SQLite.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
try
{
_builder = modelBuilder;
var typeName = typeof(T).Name;
_builder
.Entity(typeof(T))
.Property<int>("Id")
.ForSqliteHasColumnName(typeName + "Id");
}
catch (Exception e)
{
throw e;
}
}
I use EF 5 with the code first approach. Now I try to define a "code" table in which I want to have several different codes (like address code, medium code, etc.). In this table I just have the following properties: ID (Guid), Name (String), Description (String) and a discriminator (in this case something like the type of the code: address code, medium code, etc.).
So I defined the following base class:
public abstract class Code : EntityBase
{
public string Name { get; set; }
public string Beschreibung { get; set; }
}
Then I derived two classes from code
public class AddressCode : Code {}
public class MediumCode : Code {}
The class EntityBase is abstract and just defines the Id property, we use it for every POCO class...
The goal is that I can use AddressCode as a property on my address POCO class:
public class Adresse : EntityBase
{
#region Properties
public string Name1 { get; set; }
public virtual AddressCode AddressCode { get; set; }
#endregion
}
The question now is, how can I explain EF how to do that? Anyone can help?
Thanks
Marco
Thanks for your answer!
I tried to do it like you said. Unfortunately I get an error because of my EntityBase class:
public abstract class EntityBase
{
#region Properties
public virtual Guid Id { get; set; }
public virtual bool IsValid
{
get
{
{
return Validate();
}
}
}
[NotMappedAttribute]
public virtual IList<ValidationFailure> ValidationFailures { get; set; }
#endregion
#region Methods
private bool Validate()
{
var validatorFactory = new AttributedValidatorFactory();
IValidator validator = validatorFactory.GetValidator(GetType());
if (validator == null)
{
return true;
}
ValidationResult validationResult = validator.Validate(this);
ValidationFailures = validationResult.Errors;
return validationResult.IsValid;
}
#endregion
}
The error message is:
You cannot use Ignore method on the property 'ValidationFailures' on type 'Entities.AdresseCode' because this type inherits from the type 'Entities.EntityBase' where this property is mapped. To exclude this property from your model, use NotMappedAttribute or Ignore method on the base type.
As you can see I already defined the property ValidationFailures as NotMapped but still I get this error.. Do you have an idea?
Thanks
Marco
Just create a context (derived from DbContext)
public class AddressesDb : DbContext
{
public DbSet<Code> Codes { get; set; }
public DbSet<Adresse> Adressen { get; set; }
}
And (when used in code) EF will create a database with default table and column names. It will create a discriminator column of type text (nvarchar) which will contain the names of the classes that derive from Code.
If you want different names and/or types you should either use data annotations or fluent API to configure these.
Finally I got it work!
In the DBContext be aware to define DbSets for the code derived classes before all the other POCO's and then it works!
I've got the following requirement that works well in the OO space but I can't seem to get it to map back to the DB using ADO EF code first.
I have numrous products each will have different aspects (attributes but not in the sense of code attributes). For instance ring would have aspects such as mineral type = gold etc whilst a diamond would have an aspec of clarity = VVSI1.
As you can see the products very greatly in thier composition and I want a dynamic way of growing my system.
As such I've created a product class:
public class Product
{
public int id { get; set; }
public string Name { get; set; }
private List<ProductAspect> aspects = new List<ProductAspect>();
public List<ProductAspect> Aspects { get { return aspects; } set { aspects = value; } }
}
It has a list of ProductAspect which is the base class for all aspects moving forward:
public class ProductAspect
{
public int id { get; set; }
public string AspectName { get; set; }
}
I then inherit from the ProductAspect using a generic which alows me to be specific (strongly typed) about my Aspect Value:
public abstract class ProductAspect<T> : ProductAspect
{
public T AspectValue { get; set; }
}
I then create some Aspects that will allow me to decorate my product:
public class StringAspect : ProductAspect<string> { };
public class DecimalAspect : ProductAspect<decimal> { };
public class ImageAspect : ProductAspect<byte[]> { };
I then give the DbContext a try and have tried both TPH and TPC inheritance mappings.
Neither seem to work. The DB model that get's generated doesn't create a foriegn key to the StringAspect or DecimalAspect tables from the Aspect Table.
public class IxamDataContext : DbContext
{
public DbSet<Product> Products { get; set; }
public DbSet<ProductAspect> Aspects { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
AspectMapping(modelBuilder);
}
private void AspectMapping(DbModelBuilder mb)
{
//TPH
//mb.Entity<ProductAspect>()
// .Map<StringAspect>(m => m.Requires("type").HasValue("sa"))
// .Map<DecimalAspect>(m => m.Requires("type").HasValue("da"));
//TPC
//mb.Entity<StringAspect>().ToTable("StringAspect");
//mb.Entity<DecimalAspect>().ToTable("DecimalAspect");
}
}
Resulting in the following exception for this Seeding code:
Product p = new Product();
p.Name = "Diamond";
p.Aspects.Add(new StringAspect() { AspectName = "History", AspectValue = "Old and long" });
p.Aspects.Add(new DecimalAspect() { AspectName = "Weight", AspectValue= 96.5M });
context.Products.Add(p);
context.SaveChanges();
Excpetion:
EntityType 'StringAspect' does not
exist in the EntitySet
'IxamDataContext.Aspects'. Parameter
name: entity
Any ideas from the EF code first pros out there?
Entity framework doesn't support intermediate non mapped types in inheritance hierarchy. It means that you can't have this inheritance: A (mapped) -> B (not mapped) -> C (mapped). EF also doesn't support mapping generic types. It means that you must remove your generic intermediate class from the hierarchy and move AspectValue to derived types with correct type.
Maybe it's to late, but I would offer you using ComplexType attribute it will allows you to extend your types as you wish.