将 dbcontext 连接字符串传递给 DALayer

Question

我的应用程序中有 4 层 UI,DomainClass,Model(DBCntext),Repository。

在存储库中，我有一个像这样的抽象类：

 public abstract class GenericRepository<C, T> :
    IGenericRepository<T>
        where T : class
        where C : DbContext, new()
    {

        private C _entities = new C();
        public C Context
        {

            get { return _entities; }
            set { _entities = value; }
        }

        public virtual IQueryable<T> GetAll()
        {

            IQueryable<T> query = _entities.Set<T>();
            return query;
        }

        public IQueryable<T> FindBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
        {

            IQueryable<T> query = _entities.Set<T>().Where(predicate);
            return query;
        }

        public virtual void Add(T entity)
        {
            _entities.Set<T>().Add(entity);
        }

        public virtual void Delete(T entity)
        {
            _entities.Set<T>().Remove(entity);
        }

        public virtual void Edit(T entity)
        {
            _entities.Entry(entity).State = System.Data.Entity.EntityState.Modified;
        }

        public virtual void Save()
        {
            _entities.SaveChanges();
        }

    }

我所有的实体都继承自这个类：

namespace Repository
{
    public class StationRepository : GenericRepository<ShirazRailWay.ShirazRailwayEntities, DomainClass.Station>
    {
    }
}

我UI 我称这个存储库。正如你在这里看到的：

  stationrepository objnew=new stationrepository();
  obnew.getall();

在 UI 层中，我在 app.config 中有一个连接字符串，您可以在此处看到：

<connectionStrings>
    <add name="ShirazRailwayEntities" connectionString="metadata=res://*/RailWay.csdl|res://*/RailWay.ssdl|res://*/RailWay.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=****;initial catalog=DB-Metro;user id=sa;password=****;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>

但是我想给我的用户一个选项，通过这个选项他们可以自己设置connection string。所以我在 UI 层创建了一个表单，当用户尝试log in 时，它会询问他们连接字符串.我的问题是How can pass this connection string to my dbcontext？

在我的model layer(dbcontext) 我有这个：

public partial class ShirazRailwayEntities : DbContext
    {
        public ShirazRailwayEntities()
            : base("name=ShirazRailwayEntities")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }

        public DbSet<Advertisement> Advertisements { get; set; }
        public DbSet<Line> Lines { get; set; }
        public DbSet<Log> Logs { get; set; }
        public DbSet<Path> Paths { get; set; }
        public DbSet<Sensor> Sensors { get; set; }
        public DbSet<Station> Stations { get; set; }
        public DbSet<Train> Trains { get; set; }
        public DbSet<User> Users { get; set; }
        public DbSet<TimeTable> TimeTables { get; set; }
        public DbSet<ConfigFont> ConfigFonts { get; set; }
        public DbSet<ArrivalTime> ArrivalTimes { get; set; }
        public DbSet<ConfigColor> ConfigColors { get; set; }
    }

Answer 1

添加另一个接受连接字符串的构造函数：

public partial class ShirazRailwayEntities : DbContext
{
    public ShirazRailwayEntities()
        : base(name: "ShirazRailwayEntities")
    {
    }

    public ShirazRailwayEntities(string connectionName)
        : base(name: connectionName)
    {
    }
}

var context = new ShirazRailwayEntities("whatever connection name you want");