为什么 EF 急切加载包括未按预期工作？

Question

我有这个仓库，

public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
{
    private readonly DbContext context;
    private readonly DbSet<TEntity> dbEntitySet;

    public Repository(DbContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        this.context = context;
        this.dbEntitySet = context.Set<TEntity>();
    }

    public IEnumerable<TEntity> GetAll()
    {
        return this.dbEntitySet;
    }

    public IEnumerable<TEntity> GetAll(string include)
    {
        return this.dbEntitySet.Include(include);
    }

    public IEnumerable<TEntity> GetAll(string[] includes)
    {
        foreach (var include in includes)
            this.dbEntitySet.Include(include);

        return this.dbEntitySet;
    }

    public void Create(TEntity model)
    {
        this.dbEntitySet.Add(model);
    }

    public void Update(TEntity model)
    {
        this.context.Entry<TEntity>(model).State = EntityState.Modified;
    }

    public void Remove(TEntity model)
    {
        this.context.Entry<TEntity>(model).State = EntityState.Deleted;
    }

    public void Dispose()
    {
        this.context.Dispose();
    }
}

我遇到的问题是这种方法：

public IEnumerable<TEntity> GetAll(string[] includes)
{
    foreach (var include in includes)
        this.dbEntitySet.Include(include);

    return this.dbEntitySet;
}

当我运行它并在返回之前放置一个断点时，就好像 foreach 被忽略了。

上面的方法效果很好：

public IEnumerable<TEntity> GetAll(string include)
{
    return this.dbEntitySet.Include(include);
}

要调用它，我基本上是这样做的：

var a = this.Repository.GetAll(new string[] { "ForbiddenUsers", "ForbiddenGroups" }).ToList();

返回结果但不包括包含：D 如果我将调用修改为：

var a = this.Repository.GetAll("ForbiddenUsers").ToList();

它工作正常。

谁能给我一个解决方案？

Answer 1

将您的方法更改为如下所示：

public IEnumerable<TEntity> GetAll(string[] includes)
{
    var query = this.dbEntitySet;

    foreach (var include in includes)
        query = query.Include(include);

    return query;
}

Include 方法不会改变 DbSet，它只会返回一个新的 DbQuery 并包含您的包含。

Answer 2

此代码不正确：

public IEnumerable<TEntity> GetAll(string[] includes)
{
    foreach (var include in includes)
       this.dbEntitySet.Include(include);

    return this.dbEntitySet;
}

正确的代码如下：

public IEnumerable<TEntity> GetAll(string[] includes)
{
     IQueryable<T> query = this.dbEntitySet;

     foreach (var include in includes)
         query = query.Include(include);

    return query;
}

在你的位置，我将使用这样的 Lambda 表达式：

public IEnumerable<TEntity> GetAll(Expression<Func<T, object>>[] includes)
{
     IQueryable<T> query = this.dbEntitySet;

     foreach (var include in includes)
         query = query.Include(include);

     return query;
}