用于在查询中预先加载的动态包含语句 - EF 4.3.1 [英] Dynamic Include statements for eager loading in a query - EF 4.3.1

问题描述

我有这个方法:

public CampaignCreative GetCampaignCreativeById(int id)
        {
            using (var db = GetContext())
            {
                return db.CampaignCreatives
                    .Include("Placement")
                    .Include("CreativeType")                    
                    .Include("Campaign")
                    .Include("Campaign.Handshake")
                    .Include("Campaign.Handshake.Agency")
                    .Include("Campaign.Product")
                    .AsNoTracking()
                    .Where(x => x.Id.Equals(id)).FirstOrDefault();
            }
        }

我想让包含列表变得动态.我试过了:

I would like to make the list of Includes dynamic. I tried:

public CampaignCreative GetCampaignCreativeById(int id, string[] includes)
        {
            using (var db = GetContext())
            {
                var query = db.CampaignCreatives;

                foreach (string include in includes)
                {
                    query = query.Include(include);
                }

                return query.AsNoTracking()
                    .Where(x => x.Id.Equals(id)).FirstOrDefault();                    
            }
        }

但它没有编译.我收到此错误:

But it didn't compile. I got this error:

无法将类型System.Data.Entity.Infrastructure.DbQuery"隐式转换为System.Data.Entity.DbSet".存在显式转换(您是否缺少演员表?)

有谁知道如何使包含列表动态化?

Does anyone know how to make the list of Includes dynamic?

谢谢

推荐答案

使 query 变量可查询:

public CampaignCreative GetCampaignCreativeById(int id, string[] includes)
{
    using (var db = GetContext())
    {
        var query = db.CampaignCreatives.AsQueryable();
        foreach (string include in includes)
        {
            query = query.Include(include);
        }

        return query
            .AsNoTracking()
            .Where(x => x.Id.Equals(id))
            .FirstOrDefault();                    
    }
}

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