abp vnext 事务，多表查询，自定义仓储

abp vnext 中的通用仓储主要是封装的单表操作，如果是实现事务的话最好还是封装一个自定义仓储。

自定义仓储大概的结构如下：

然后使用事务的方式和使用ef就完全一样了

我们这里是在数据库访问层用的ef

/// <summary>
/// 事务示例
/// </summary>
/// <param name="landInfo"></param>
/// <param name="userInfo"></param>
/// <returns></returns>
public async Task<int> UpdateTrans(LandInfo landInfo, UserInfo userInfo)
{
    var getDbContext = await GetDbContextAsync();
    using (var transaction = getDbContext.Database.BeginTransaction())
    {
        try
        {                
            getDbContext.LandInfo.Update(landInfo);
            getDbContext.SaveChanges();
            userInfo.UserDetailsId = landInfo.Id;
            getDbContext.UserInfo.Add(userInfo);
            getDbContext.SaveChanges();
            transaction.Commit();
            return 1;
        }
        catch (Exception)
        {
            transaction.Rollback();
            return -1;
        }
    }
}

自定义仓储下多表查询的话，也是和使用ef一样了

/// <summary>
/// 多表查询示例
/// </summary>
public async void JoinTemp()
{
    var dbContext = await GetDbContextAsync();
    /*表1:UserInfo ; 表2：UserDetails ; 关联条件 UserInfo.UserDetailsId = UserDetails.Id
        返回结果表1的UserName字段，表2的avatar字段
        */
    //方法1
    dbContext.UserInfo.Join(dbContext.UserDetails, a => a.UserDetailsId, b => b.Id, (a, b) => new {
        userName = a.UserName,
        avatar = b.avatar
    });
    //方法2：
    var query = from u in dbContext.UserInfo
                join p in dbContext.UserDetails on u.UserDetailsId equals p.Id
                select new
                {
                    username = u.UserName,
                    avatar = p.avatar
                };
    //方法3：直接执行sql语句返回结果
}

整体点的代码贴一下

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Volo.Abp.Domain.Repositories.EntityFrameworkCore;
using Volo.Abp.EntityFrameworkCore;
using WY.JBLand.Domain.Land;
using WY.JBLand.Domain.User;
namespace WY.JBLand.EntityFrameworkCore.Land
{
    public class LandInfoRepository : EfCoreRepository<WyJBLandDbContext, LandInfo, int>, ILandInfoRepository
    {
        public LandInfoRepository(IDbContextProvider<WyJBLandDbContext> dbContextProvider) : base(dbContextProvider)
        {
        }
        /// <summary>
        /// 多表查询示例
        /// </summary>
        public async void JoinTemp()
        {
            var dbContext = await GetDbContextAsync();
            /*表1:UserInfo ; 表2：UserDetails ; 关联条件 UserInfo.UserDetailsId = UserDetails.Id
                返回结果表1的UserName字段，表2的avatar字段
                */
            //方法1
            dbContext.UserInfo.Join(dbContext.UserDetails, a => a.UserDetailsId, b => b.Id, (a, b) => new
            {
                userName = a.UserName,
                avatar = b.avatar
            });
            //方法2：
            var query = from u in dbContext.UserInfo
                        join p in dbContext.UserDetails on u.UserDetailsId equals p.Id
                        select new
                        {
                            username = u.UserName,
                            avatar = p.avatar
                        };
            //方法3：直接执行sql语句返回结果
        }
        /// <summary>
        /// 事务示例
        /// </summary>
        /// <param name="landInfo"></param>
        /// <param name="userInfo"></param>
        /// <returns></returns>
        public async Task<int> UpdateTrans(LandInfo landInfo, UserInfo userInfo)
        {
            var getDbContext = await GetDbContextAsync();
            using (var transaction = getDbContext.Database.BeginTransaction())
            {
                try
                {
                    getDbContext.LandInfo.Update(landInfo);
                    getDbContext.SaveChanges();
                    userInfo.UserDetailsId = landInfo.Id;
                    getDbContext.UserInfo.Add(userInfo);
                    getDbContext.SaveChanges();
                    transaction.Commit();
                    return 1;
                }
                catch (Exception)
                {
                    transaction.Rollback();
                    return -1;
                }
            }
        }
        public async Task<LandInfo> FindByNameAsync(string name)
        {
            var dbSet = await GetDbSetAsync();
            return await dbSet.FirstOrDefaultAsync(author => author.landName == name);
        }
        public async Task<List<LandInfo>> GetListAsync(int skipCount, int maxResultCount, string filter = null)
        {
            var dbSet = await GetDbSetAsync();
            return await dbSet
                .WhereIf(
                    !filter.IsNullOrWhiteSpace(),
                    author => author.landName.Contains(filter)
                 )
                .OrderBy(a => a.Id)
                .Skip(skipCount)
                .Take(maxResultCount)
                .ToListAsync();
        }
    }
}

当然使用通用仓储也可以实现多表查询，比如通过通用仓储拿到上下文对象后在去join，但不建议这么去使用

比如连表查询join,可以这样：

public async void JoinTemp() 
{
    WyJBLandDbContext dbContext = await _landInfoRepository.GetDbContextAsync() as WyJBLandDbContext;
    dbContext.UserInfo.Join(dbContext.UserDetails, a => a.UserDetailsId, b => b.Id, (a, b) => new
    {
        userName = a.UserName,
        avatar = b.avatar
    });
}

但是这种直接在应用层使用上下文对象的方法是不科学的，依赖性过于强了

我们建议使用的方法是通过通用仓储拿到GetQueryableAsync（）后实现join

如下：

public async void TestJoin()
{
    var queryable = (from fileManager in await _fileManagerRepository.GetQueryableAsync()
                        join fileType in await _fileTypeRepository.GetQueryableAsync() on fileManager.FileTypeId equals fileType.Id
                        select new
                        {
                            fileName = fileManager.FileName,
                            fileTypeName = fileType.FileTypeName
                        });
    var reuslt = queryable.ToList();
}

这个和直接使用原生ef实现join其实是一个意思，原生ef通过上下文点出来的实体是一个DbSet:

而DbSet其实本身也是IQueryable，所以通过GetQueryableAsync()获取到实体的IQueryable对象当然也可以直接join了