實體框架代碼優先方法的動態連接字符串

Question

我正在使用帶有代碼優先方法和工作單元模式的實體框架6.0。 我想動態地建立連接字符串並從數據庫中獲取數據。 如果我具有連接字符串的web.config標記，則數據庫連接可以正常工作。 但是，我不想為連接字符串使用web.config標記。 我看到了許多與此有關的問題，但沒有發現與代碼優先方法有關的問題。 請讓我知道如何實現這一目標。

-------------------- Repository.cs --------------------

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.Entity;
using System.Linq.Expressions;
using Commons.DTO;

namespace Repository
{
    public class Repository<TEntity> where TEntity : class
    {
        internal CommonsDbContext context;
        internal DbSet<TEntity> dbSet;

        public Repository(CommonsDbContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            this.context = context;
            this.dbSet = context.Set<TEntity>();
        }

        public virtual IEnumerable<TEntity> Get(Expression<Func<TEntity, bool>> filter = null, Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null, string includeProperties = "")
        {
            IQueryable<TEntity> query = dbSet;

            if (filter != null)
                query = query.Where(filter);

            string[] properties = includeProperties.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            foreach (var includeProperty in properties)
                query = query.Include(includeProperty);

            if (orderBy != null)
                return orderBy(query).ToList();
            else
                return query.ToList();
        }

        public virtual TEntity GetByID(object id)
        {
            return dbSet.Find(id);
        }

        public virtual void Insert(TEntity entity)
        {
            dbSet.Add(entity);
        }

        public virtual void Delete(object id)
        {
            TEntity entityToDelete = dbSet.Find(id);
            Delete(entityToDelete);
        }

        public virtual void Delete(TEntity entityToDelete)
        {
            if (context.Entry(entityToDelete).State == EntityState.Detached)
                dbSet.Attach(entityToDelete);
            dbSet.Remove(entityToDelete);
        }

        public virtual void Update(TEntity entityToUpdate)
        {
            dbSet.Attach(entityToUpdate);
            context.Entry(entityToUpdate).State = EntityState.Modified;
        }

        public virtual bool IsValid(TEntity entityToValid, Expression<Func<TEntity, bool>> filter)
        {
            return dbSet.Where(filter).Any();
        }
    }
}

-------------------- UnitOfWork.cs --------------------
using System;
using Commons.DTO;

namespace Repository
{
    public class UnitOfWork : IDisposable
    {
        protected CommonsDbContext dbContext = null;

        public UnitOfWork()
        {
            dbContext = new CommonsDbContext();
        }

        public UnitOfWork(CommonsDbContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            this.dbContext = context;
        }

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

        #region IDisposable Members
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                dbContext.Dispose();
                dbContext = null;
            }
        }

        ~UnitOfWork()
        {
            Dispose(false);
        }
        #endregion
    }
}
-------------CommonsDbContext.cs
using System.Data.Entity;

namespace Commons.DTO
{
    public class CommonsDbContext : DbContext
    {
        public CommonsDbContext() : base("name=DbContext")
        {
            Database.SetInitializer<CommonsDbContext>(null);
        }

        public CommonsDbContext(string nameOrConnectionString) : base(nameOrConnectionString)
        {

        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new ApplicationMapper());
        }
        public DbSet<Application> Applications { get; set; }
    }
}

Answer 1

您的問題是您要專門傳遞一個連接字符串名稱，該名稱只能在web.config或app.config上進行搜索。 如果不想使用web.config請將其更改為完整的連接字符串：

public class CommonsDbContext : DbContext
{
    //Approach 1:
    private const connectionString = "...";

    public CommonsDbContext() : base(connectionString)
    {
        Database.SetInitializer<CommonsDbContext>(null);
    }

    //Approach 2:

    public static CommonsDbContext GetContext()
    {
        var builder = new SqlConnectionStringBuilder();

        // add data here

        return new CommonsDbContext(builder.ConnectionString);
    }

    private CommonsDbContext(string connString) : base(connString)
    {
        Database.SetInitializer<CommonsDbContext>(null);
    }
}

請注意，但是，將連接字符串放置在web.config比其他任何地方都要好得多。