与实体框架核心删除dbData.Database。我找不到一个解决方案来构建一个原始的SQL查询为我的全文搜索查询,将返回表数据和排名。

我所见过的在实体框架核心中构建原始SQL查询的唯一方法是通过dbData.Product。FromSql(“SQL脚本”);这是没有用的,因为我没有DbSet,将映射我在查询中返回的排名。

有什么想法?


当前回答

你也可以使用QueryFirst。和Dapper一样,这完全不在EF的范围内。与Dapper(或EF)不同的是,您不需要维护POCO,只需在真实环境中编辑sql sql,并根据DB不断对其进行重新验证。免责声明:我是QueryFirst的作者。

其他回答

添加Nuget包- Microsoft.EntityFrameworkCore.Relational

using Microsoft.EntityFrameworkCore;
...
await YourContext.Database.ExecuteSqlCommandAsync("... @p0, @p1", param1, param2 ..)

这将以int形式返回行号

参见- https://learn.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.relationaldatabasefacadeextensions.executesqlcommand?view=efcore-3.0

在实体框架6中,你可以执行如下内容

创建模态类为

Public class User
{
        public int Id { get; set; }
        public string fname { get; set; }
        public string lname { get; set; }
        public string username { get; set; }
}

执行Raw DQL SQl命令如下所示:

var userList = datacontext.Database.SqlQuery<User>(@"SELECT u.Id ,fname , lname ,username FROM dbo.Users").ToList<User>();

你也可以使用QueryFirst。和Dapper一样,这完全不在EF的范围内。与Dapper(或EF)不同的是,您不需要维护POCO,只需在真实环境中编辑sql sql,并根据DB不断对其进行重新验证。免责声明:我是QueryFirst的作者。

这样做的实体框架核心5,需要安装

Microsoft.EntityFrameworkCore.Relational

助手扩展方法

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.Storage;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;


public static class EfHelper
{
    public static DbTransaction GetDbTransaction(this IDbContextTransaction source)
    {
        return (source as IInfrastructure<DbTransaction>).Instance;
    }

    private class PropertyMapp
    {
        public string Name { get; set; }
        public Type Type { get; set; }

        public bool IsSame(PropertyMapp mapp)
        {
            if (mapp == null)
            {
                return false;
            }
            bool same = mapp.Name == Name && mapp.Type == Type;
            return same;
        }
    }

    public static IEnumerable<T> FromSqlQuery<T>(this DbContext context, string query, params object[] parameters) where T : new()
    {
        const BindingFlags flags = BindingFlags.Public | BindingFlags.Instance | BindingFlags.NonPublic;
        List<PropertyMapp> entityFields = (from PropertyInfo aProp in typeof(T).GetProperties(flags)
                                           select new PropertyMapp
                                           {
                                               Name = aProp.Name,
                                               Type = Nullable.GetUnderlyingType(aProp.PropertyType) ?? aProp.PropertyType
                                           }).ToList();
        List<PropertyMapp> dbDataReaderFields = new List<PropertyMapp>();
        List<PropertyMapp> commonFields = null;

        using (var command = context.Database.GetDbConnection().CreateCommand())
        {
            if (command.Connection.State != ConnectionState.Open)
            {
                command.Connection.Open();
            }
            var currentTransaction = context.Database.CurrentTransaction;
            if (currentTransaction != null)
            {
                command.Transaction = currentTransaction.GetDbTransaction();
            }
            command.CommandText = query;
            if (parameters.Any())
            {
                command.Parameters.AddRange(parameters);
            }
            using (var result = command.ExecuteReader())
            {
                while (result.Read())
                {
                    if (commonFields == null)
                    {
                        for (int i = 0; i < result.FieldCount; i++)
                        {
                            dbDataReaderFields.Add(new PropertyMapp { Name = result.GetName(i), Type = result.GetFieldType(i) });
                        }
                        commonFields = entityFields.Where(x => dbDataReaderFields.Any(d => d.IsSame(x))).Select(x => x).ToList();
                    }

                    var entity = new T();
                    foreach (var aField in commonFields)
                    {
                        PropertyInfo propertyInfos = entity.GetType().GetProperty(aField.Name);
                        var value = (result[aField.Name] == DBNull.Value) ? null : result[aField.Name]; //if field is nullable
                        propertyInfos.SetValue(entity, value, null);
                    }
                    yield return entity;
                }
            }
        }
    }

    /*
     * https://entityframeworkcore.com/knowledge-base/35631903/raw-sql-query-without-dbset---entity-framework-core
     */
    public static IEnumerable<T> FromSqlQuery<T>(this DbContext context, string query, Func<DbDataReader, T> map, params object[] parameters)
    {
        using (var command = context.Database.GetDbConnection().CreateCommand())
        {
            if (command.Connection.State != ConnectionState.Open)
            {
                command.Connection.Open();
            }
            var currentTransaction = context.Database.CurrentTransaction;
            if (currentTransaction != null)
            {
                command.Transaction = currentTransaction.GetDbTransaction();
            }
            command.CommandText = query;
            if (parameters.Any())
            {
                command.Parameters.AddRange(parameters);
            }
            using (var result = command.ExecuteReader())
            {
                while (result.Read())
                {
                    yield return map(result);
                }
            }
        }
    }
}

模型

public class UserModel
{
    public string Name { get; set; }
    public string Email { get; set; }
    public bool? IsDeleted { get; set; }
}

手动映射

List<UserModel> usersInDb = Db.FromSqlQuery
(
    "SELECT Name, Email FROM Users WHERE Name=@paramName",
    x => new UserModel 
    { 
        Name = (string)x[0], 
        Email = (string)x[1] 
    },
    new SqlParameter("@paramName", user.Name)
)
.ToList();

usersInDb = Db.FromSqlQuery
(
    "SELECT Name, Email FROM Users WHERE Name=@paramName",
    x => new UserModel 
    { 
        Name = x["Name"] is DBNull ? "" : (string)x["Name"], 
        Email = x["Email"] is DBNull ? "" : (string)x["Email"] 
    },
    new SqlParameter("@paramName", user.Name)
)
.ToList();

使用反射自动映射

List<UserModel> usersInDb = Db.FromSqlQuery<UserModel>
(
    "SELECT Name, Email, IsDeleted FROM Users WHERE Name=@paramName",
    new SqlParameter("@paramName", user.Name)
)
.ToList();

不是直接针对OP的场景,但因为我一直在努力解决这个问题,我想放弃这些让DbContext更容易执行原始SQL的ex.方法:

public static class DbContextCommandExtensions
{
  public static async Task<int> ExecuteNonQueryAsync(this DbContext context, string rawSql,
    params object[] parameters)
  {
    var conn = context.Database.GetDbConnection();
    using (var command = conn.CreateCommand())
    {
      command.CommandText = rawSql;
      if (parameters != null)
        foreach (var p in parameters)
          command.Parameters.Add(p);
      await conn.OpenAsync();
      return await command.ExecuteNonQueryAsync();
    }
  }

  public static async Task<T> ExecuteScalarAsync<T>(this DbContext context, string rawSql,
    params object[] parameters)
  {
    var conn = context.Database.GetDbConnection();
    using (var command = conn.CreateCommand())
    {
      command.CommandText = rawSql;
      if (parameters != null)
        foreach (var p in parameters)
          command.Parameters.Add(p);
      await conn.OpenAsync();
      return (T)await command.ExecuteScalarAsync();
    }
  }
}