在使用存储库include（）方法 [英] Use Include() method in repository

问题描述

我有EF 5以下内容：

I have the following with EF 5:

var a = context.Posts.Include(x => x.Pack).Select(x => x.Pack.Id).ToList();

这工作。然后我试图在我的通用存储库复制这样的：

This works. Then I tried to replicate this in my generic repository:

public IQueryable<T> Include<T>(Expression<Func<T, Boolean>> criteria) where T : class
{
    return _context.Set<T>().Include(criteria);
}

但在这种情况下，我不能做到以下几点：

But in this case I am not able to do the following:

var b = repository.Include<Post>(x => x.Pack).Select(x => x.Pack.Id).ToList();

我得到的错误：

I get the error:

无法隐式转换类型'Data.Entities.Pack'到'布尔

Cannot implicitly convert type 'Data.Entities.Pack' to 'bool'

我怎样才能解决这个问题？

How can I solve this?

我应该在我的include（）方法改变？

What should I change in my Include() method?

推荐答案

尝试：

修改

Expression<Func<T, Boolean>> criteria

要

Expression<Func<T, object>> criteria

编辑：
。要包括多个实体，则需要添加一个包括延期

To Include multiple entities, you need to add an "include" extension:

public static class IncludeExtension
{
    public static IQueryable<TEntity> Include<TEntity>(this IDbSet<TEntity> dbSet,
                                            params Expression<Func<TEntity, object>>[] includes)
                                            where TEntity : class
    {
        IQueryable<TEntity> query = null;
        foreach (var include in includes)
        {
            query = dbSet.Include(include);
        }

        return query == null ? dbSet : query;
    }
}

然后你可以使用这样的：

Then you can use it like this:

repository.Include(x => x.Pack, x => x.Pack.Roles, ...).Select(x => x.Pack.Id).ToList();

只要确保库返回DbSet对象。

Just make sure "repository" return a "DbSet" Object.

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