ThenInclude 在 EF Core 查询中无法识别

问题描述

我的 IQueryable 看起来像这样:

 IQueryable查询 = context.Set();query = query.Include("Car").ThenInclude("Model");

IQueryable"不包含ThenInclude"的定义并且没有扩展方法ThenInclude"接受第一个参数可以找到类型IQueryable"(您是否缺少使用指令或程序集引用?)

我有需要的所有参考资料:

使用 Content.Data.Models;使用 Microsoft.EntityFrameworkCore；使用系统；使用 System.Collections.Generic;使用 System.Linq；使用 System.Linq.Expressions;使用 System.Threading.Tasks;

为什么它不识别 ThenInclude?

查询:

[Content.Data.Models.Article]).Where(x => ((x.BaseContentItem.SiteId == value(Content.Business.Managers.ArticleManager+<>c__DisplayClass8_0).id) AndAlso x.BaseContentItem.IsActive) AndAlso x.BaseContentItem.IsLive)).Include("BaseContentItem").Include("BaseContentItem.TopicTag").Include("MainImage")}

在我包含 .Include("BaseContentItem.TopicTag") 部分后失败.

所以我刚刚阅读了通用存储库，您丢失了 ThenInclude.我正在使用这个通用代表:

公共类 ReadOnlyRepository: IReadOnlyRepository其中 TContext : DbContext{受保护的只读 TContext 上下文；公共 ReadOnlyRepository(TContext 上下文){this.context = 上下文；}私有 IQueryableGetQueryable(表达式<Func<TEntity，bool>过滤器 = 空，FuncorderBy = 空，字符串 includeProperties = null,内部?跳过 = 空，内部?取=空)其中 TEntity :类，IEntity{包含属性 = 包含属性 ??字符串.空；IQueryable查询 = context.Set();如果(过滤器！= null){查询 = query.Where(filter);}foreach (var includeProperty in includeProperties.Split(新字符[] { ',' }, StringSplitOptions.RemoveEmptyEntries)){查询 = query.Include(includeProperty);}如果(orderBy ！= null){查询 = orderBy(查询)；}如果(跳过.HasValue){查询 = query.Skip(skip.Value);}如果(采取.HasValue){查询 = query.Take(take.Value);}返回查询；}

解决方案

ThenInclude 仅在您使用带有 lambda 表达式参数的 Include 重载时可用:

query = query.Include(e => e.Car).ThenInclude(e => e.Model);

当您使用带有字符串参数的 Include 重载时，不需要 ThenInclude，因为您可以在传递的字符串中指定整个属性路径:

query = query.Include("Car.Model");

My IQueryable looks like this:

 IQueryable<TEntity> query = context.Set<TEntity>();
query = query.Include("Car").ThenInclude("Model");

I have all references needed:

using Content.Data.Models;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading.Tasks;

Why it doesn't recognize ThenInclude?

Query:

[Content.Data.Models.Article]).Where(x => (((x.BaseContentItem.SiteId == value(Content.Business.Managers.ArticleManager+<>c__DisplayClass8_0).id) AndAlso x.BaseContentItem.IsActive) AndAlso x.BaseContentItem.IsLive)).Include("BaseContentItem").Include("BaseContentItem.TopicTag").Include("MainImage")}

Fails after I include .Include("BaseContentItem.TopicTag") part.

So I just read that with generic repository you lose ThenInclude. I am using thise generic rep:

public class ReadOnlyRepository<TContext> : IReadOnlyRepository
            where TContext : DbContext
    {
        protected readonly TContext context;

        public ReadOnlyRepository(TContext context)
        {
            this.context = context;
        }

        private IQueryable<TEntity> GetQueryable<TEntity>(
            Expression<Func<TEntity, bool>> filter = null,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
            string includeProperties = null,
            int? skip = null,
            int? take = null)
            where TEntity : class, IEntity
        {
            includeProperties = includeProperties ?? string.Empty;
            IQueryable<TEntity> query = context.Set<TEntity>();

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

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

            if (orderBy != null)
            {
                query = orderBy(query);
            }

            if (skip.HasValue)
            {
                query = query.Skip(skip.Value);
            }

            if (take.HasValue)
            {
                query = query.Take(take.Value);
            }

            return query;
        }

解决方案

ThenInclude is available only when you use the Include overload with lambda expression parameter:

query = query.Include(e => e.Car).ThenInclude(e => e.Model);

When you use the Include overload with string argument, there is no need of ThenInclude since you can specify the whole property path in the passed string:

query = query.Include("Car.Model");

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