repository-pattern

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key

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Edit: Original answer used Find instead of Local.SingleOrDefault. It worked in combination with @Juan’s Save method but it could cause unnecessary queries to database and else part was probably never executed (executing the else part would cause exception because Find already queried the database and hadn’t found the entity so it could not be updated). … Read more

Repository Design Pattern with Dapper

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Sure, a function to create and dispose your Connection will work great. protected void Execute(Action<IDbConnection> query) { using (IDbConnection db = new SqlConnection(ConfigurationManager.ConnectionStrings[“myDB”].ConnectionString)) { query.Invoke(db); } } And your simplified call site: public void SaveCustomer(CustomerDTO custDTO) { Execute(db => db.Execute(saveCustSp, custDTO, CommandType.StoredProcedure)); } With Return Values: public T Get<T>(Func<IDbConnection, T> query) { using (IDbConnection db … Read more

Is it ok for entities to access repositories?

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it’s not a horrible violation of DDD it’s a horrible violation of… well… it’s just plain horrible (i say this tongue in cheek) :). First off, your entity becomes dependent on having a repository… that’s not ideal. Ideally you’d want to have your repository create the Person and then assign it everything it needs to … Read more

using stored procedure in entity framework

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You need to create a model class that contains all stored procedure properties like below. Also because Entity Framework model class needs primary key, you can create a fake key by using Guid. public class GetFunctionByID { [Key] public Guid? GetFunctionByID { get; set; } // All the other properties. } then register the GetFunctionByID … Read more

EF Including Other Entities (Generic Repository pattern)

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Use just the Include extension on IQueryable. It is available in EF 4.1 assembly. If you don’t want to reference that assembly in your upper layers create wrapper extension method in your data access assembly. Here you have example: public static IQueryable<T> IncludeMultiple<T>(this IQueryable<T> query, params Expression<Func<T, object>>[] includes) where T : class { if … Read more

Entity Framework 4 CTP 4 / CTP 5 Generic Repository Pattern and Unit Testable

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Start with you DbContext, create a new file called Database.cs: Database.cs public class Database : DbContext { private IDbSet<Post> _posts; public IDbSet<Post> Posts { get { return _posts ?? (_posts = DbSet<Post>()); } } public virtual IDbSet<T> DbSet<T>() where T : class { return Set<T>(); } public virtual void Commit() { base.SaveChanges(); } } Define … Read more

Method cannot be translated into a store expression

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Reason: By design, LINQ to Entities requires the whole LINQ query expression to be translated to a server query. Only a few uncorrelated subexpressions (expressions in the query that do not depend on the results from the server) are evaluated on the client before the query is translated. Arbitrary method invocations that do not have … Read more

How to implement Unit Of Work pattern with Dapper?

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This Git project is very helpful. I started from the same and did some changes as per my need. public sealed class DalSession : IDisposable { public DalSession() { _connection = new OleDbConnection(DalCommon.ConnectionString); _connection.Open(); _unitOfWork = new UnitOfWork(_connection); } IDbConnection _connection = null; UnitOfWork _unitOfWork = null; public UnitOfWork UnitOfWork { get { return _unitOfWork; … Read more

Generic Repository or Specific Repository for each entity?

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To begin with, if you are using full ORM like Entity Framework or NHibernate, you should avoid implementing additional layer of Repository and Unit Of Work. This is because; the ORM itself exposes both Generic Repository and Unit Of Work. In case of EF, your DbContext is Unit Of Work and DbSet is Generic Repository. … Read more

How are Spring Data repositories actually implemented?

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First of all, there’s no code generation going on, which means: no CGLib, no byte-code generation at all. The fundamental approach is that a JDK proxy instance is created programmatically using Spring’s ProxyFactory API to back the interface and a MethodInterceptor intercepts all calls to the instance and routes the method into the appropriate places: … Read more