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

试试这个(创建扩展方法)

public static List<T> ExecuteQuery<T>(this dbContext db, string query) where T : class, new()
        {
            using (var command = db.Database.GetDbConnection().CreateCommand())
            {
                command.CommandText = query;
                command.CommandType = CommandType.Text;

                db.Database.OpenConnection();

                using (var reader = command.ExecuteReader())
                {
                    var lst = new List<T>();
                    var lstColumns = new T().GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
                    while (reader.Read())
                    {
                        var newObject = new T();
                        for (var i = 0; i < reader.FieldCount; i++)
                        {
                            var name = reader.GetName(i);
                            PropertyInfo prop = lstColumns.FirstOrDefault(a => a.Name.ToLower().Equals(name.ToLower()));
                            if (prop == null)
                            {
                                continue;
                            }
                            var val = reader.IsDBNull(i) ? null : reader[i];
                            prop.SetValue(newObject, val, null);
                        }
                        lst.Add(newObject);
                    }

                    return lst;
                }
            }
        }

用法:

var db = new dbContext();
string query = @"select ID , Name from People where ... ";
var lst = db.ExecuteQuery<PeopleView>(query);

我的模型:(不在DbSet中):

public class PeopleView
{
    public int ID { get; set; }
    public string Name { get; set; }
}

在。net core 2.2和3.0中测试。

注意:该方案性能较慢

其他回答

我更新了扩展方法从@AminRostami返回IAsyncEnumerable(这样LINQ过滤可以应用),它的映射模型列名的记录从DB返回到模型(EF Core 5测试):

扩展本身:

public static class QueryHelper
{
    private static string GetColumnName(this MemberInfo info)
    {
        List<ColumnAttribute> list = info.GetCustomAttributes<ColumnAttribute>().ToList();
        return list.Count > 0 ? list.Single().Name : info.Name;
    }
    /// <summary>
    /// Executes raw query with parameters and maps returned values to column property names of Model provided.
    /// Not all properties are required to be present in model (if not present - null)
    /// </summary>
    public static async IAsyncEnumerable<T> ExecuteQuery<T>(
        [NotNull] this DbContext db,
        [NotNull] string query,
        [NotNull] params SqlParameter[] parameters)
        where T : class, new()
    {
        await using DbCommand command = db.Database.GetDbConnection().CreateCommand();
        command.CommandText = query;
        command.CommandType = CommandType.Text;
        if (parameters != null)
        {
            foreach (SqlParameter parameter in parameters)
            {
                command.Parameters.Add(parameter);
            }
        }
        await db.Database.OpenConnectionAsync();
        await using DbDataReader reader = await command.ExecuteReaderAsync();
        List<PropertyInfo> lstColumns = new T().GetType()
            .GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
        while (await reader.ReadAsync())
        {
            T newObject = new();
            for (int i = 0; i < reader.FieldCount; i++)
            {
                string name = reader.GetName(i);
                PropertyInfo prop = lstColumns.FirstOrDefault(a => a.GetColumnName().Equals(name));
                if (prop == null)
                {
                    continue;
                }
                object val = await reader.IsDBNullAsync(i) ? null : reader[i];
                prop.SetValue(newObject, val, null);
            }
            yield return newObject;
        }
    }
}

使用的模型(注意列名与实际的属性名不同):

public class School
{
    [Key] [Column("SCHOOL_ID")] public int SchoolId { get; set; }

    [Column("CLOSE_DATE", TypeName = "datetime")]
    public DateTime? CloseDate { get; set; }

    [Column("SCHOOL_ACTIVE")] public bool? SchoolActive { get; set; }
}

实际的用法:

public async Task<School> ActivateSchool(int schoolId)
{
    // note that we're intentionally not returning "SCHOOL_ACTIVE" with select statement
    // this might be because of certain IF condition where we return some other data
    return await _context.ExecuteQuery<School>(
        "UPDATE SCHOOL SET SCHOOL_ACTIVE = 1 WHERE SCHOOL_ID = @SchoolId; SELECT SCHOOL_ID, CLOSE_DATE FROM SCHOOL",
        new SqlParameter("@SchoolId", schoolId)
    ).SingleAsync();
}

在其他答案的基础上,我写了这个助手来完成这个任务,包括示例用法:

public static class Helper
{
    public static List<T> RawSqlQuery<T>(string query, Func<DbDataReader, T> map)
    {
        using (var context = new DbContext())
        {
            using (var command = context.Database.GetDbConnection().CreateCommand())
            {
                command.CommandText = query;
                command.CommandType = CommandType.Text;

                context.Database.OpenConnection();

                using (var result = command.ExecuteReader())
                {
                    var entities = new List<T>();

                    while (result.Read())
                    {
                        entities.Add(map(result));
                    }

                    return entities;
                }
            }
        }
    }

用法:

public class TopUser
{
    public string Name { get; set; }

    public int Count { get; set; }
}

var result = Helper.RawSqlQuery(
    "SELECT TOP 10 Name, COUNT(*) FROM Users U"
    + " INNER JOIN Signups S ON U.UserId = S.UserId"
    + " GROUP BY U.Name ORDER BY COUNT(*) DESC",
    x => new TopUser { Name = (string)x[0], Count = (int)x[1] });

result.ForEach(x => Console.WriteLine($"{x.Name,-25}{x.Count}"));

我计划在添加内置支持后尽快摆脱它。根据EF核心团队的Arthur Vickers的声明,这是2.0后的优先级。这个问题正在被追踪。

我使用Dapper绕过了Entity框架Core的这个约束。

IDbConnection.Query

正在处理带有多个参数的SQL查询或存储过程。 顺便说一下,它更快一些(参见基准测试)

Dapper很容易学。编写和运行带参数的存储过程需要15分钟。无论如何,你可以同时使用EF和Dapper。下面是一个例子:

 public class PodborsByParametersService
{
    string _connectionString = null;


    public PodborsByParametersService(string connStr)
    {
        this._connectionString = connStr;

    }

    public IList<TyreSearchResult> GetTyres(TyresPodborView pb,bool isPartner,string partnerId ,int pointId)
    {

        string sqltext  "spGetTyresPartnerToClient";

        var p = new DynamicParameters();
        p.Add("@PartnerID", partnerId);
        p.Add("@PartnerPointID", pointId);

        using (IDbConnection db = new SqlConnection(_connectionString))
        {
            return db.Query<TyreSearchResult>(sqltext, p,null,true,null,CommandType.StoredProcedure).ToList();
        }


        }
}

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();

查询数据:不存在实体

               string query = "SELECT r.Name as roleName, ur.roleId, u.Id as userId   FROM dbo.AspNetUserRoles AS ur INNER JOIN dbo.AspNetUsers AS u ON ur.UserId = u.Id INNER JOIN dbo.AspNetRoles AS r ON ur.RoleId = r.Id ";

               ICollection<object> usersWithRoles = new List<object>();
                using (var command = _identityDBContext.Database.GetDbConnection().CreateCommand())
                {
                    command.CommandText = query;
                    command.CommandType = CommandType.Text;

                    await _identityDBContext.Database.OpenConnectionAsync();

                    using (var reader = await command.ExecuteReaderAsync())
                    {      
                        while (await reader.ReadAsync())
                        {
                            usersWithRoles.Add(new { 
                                roleName = reader.GetFieldValueAsync<string>(0).Result, 
                                roleId = reader.GetFieldValueAsync<string>(1).Result,
                                userId = reader.GetFieldValueAsync<string>(2).Result
                            });
                        }    
                    }
                }

详细:

 [HttpGet]
    [Route("GetAllUsersWithRoles")]
    public async Task<IActionResult> GetAllUsersWithRoles()
    {
        string query = "SELECT r.Name as roleName, ur.roleId, u.Id as userId   FROM dbo.AspNetUserRoles AS ur INNER JOIN dbo.AspNetUsers AS u ON ur.UserId = u.Id INNER JOIN dbo.AspNetRoles AS r ON ur.RoleId = r.Id ";
        try
        {
            ICollection<object> usersWithRoles = new List<object>();
            using (var command = _identityDBContext.Database.GetDbConnection().CreateCommand())
            {
                command.CommandText = query;
                command.CommandType = CommandType.Text;

                await _identityDBContext.Database.OpenConnectionAsync();

                using (var reader = await command.ExecuteReaderAsync())
                {      
                    while (await reader.ReadAsync())
                    {
                        usersWithRoles.Add(new { 
                            roleName = reader.GetFieldValueAsync<string>(0).Result, 
                            roleId = reader.GetFieldValueAsync<string>(1).Result,
                            userId = reader.GetFieldValueAsync<string>(2).Result
                        });
                    }    
                }
            }
                return StatusCode(200, usersWithRoles); // Get all users   
        }
        catch (Exception e)
        {
            return StatusCode(500, e);
        }
    }

结果如下所示:

[
  {
    "roleName": "admin",
    "roleId": "7c9cb1be-e987-4ec1-ae4d-e4c9790f57d8",
    "userId": "12eadc86-6311-4d5e-8be8-df30799df265"
  },
  {
    "roleName": "user",
    "roleId": "a0d5ef46-b1e6-4a53-91ce-9ff5959f1ed8",
    "userId": "12eadc86-6311-4d5e-8be8-df30799df265"
  },
  {
    "roleName": "user",
    "roleId": "a0d5ef46-b1e6-4a53-91ce-9ff5959f1ed8",
    "userId": "3e7cd970-8c52-4dd1-847c-f824671ea15d"
  }
]