How to call Stored Procedure with join on multiple tables in Entity Framework Core?

Question

I have to call a stored procedure which is selecting records from multiple tables.

I have tried the following code, but it's returning null for columns from other tables than the entity class.

private async Task<IEnumerable<TEntity>> InvokeStoredProcedureAsync(string input = "")
{
    var storedProcedureName = "sp_BulkSelect";

    using (var db = new MyDbContext(_options))
    {
        var result = await db.Set<TEntity>().FromSql(storedProcedureName + " @inputIds", new SqlParameter("inputIds", input)).ToListAsync();
        return result;
    }
}

Stored procedure:

SELECT 
    [MainTable].[Id],
    [Table1Id],
    [Table2Id],
    [MainTable].[Table1Code],
    [Table2].[Table2Code]
FROM
    [MainTable] [MainTable]
LEFT JOIN 
    [Table1] [Table1] ON [MainTable].Table1Id = [Table1].[Id]
LEFT JOIN 
    [Table2] [Table2] ON [MainTable].[Table2Id] = [Table2].[Id];

MainTable class:

[Table("MainTable")]
public class MainTable : FullAuditedEntity
{

    [ForeignKey("Table1Id")]
    public virtual Table1 Table1 { get; set; }
    public virtual int Table1Id { get; set; }

    [ForeignKey("Table2Id")]
    public virtual Table2 Table2 { get; set; }
    public virtual int? Table2Id { get; set; }      

}

So when I call this stored procedure, Table1Code and Table2Code are missing in the return value.

I tried to add the following code in MainTable class, but its also not working.

[NotMapped]
public virtual string Table2Code { get; set; }

[NotMapped]
public virtual string Table1Code { get; set; }

Then I removed [NotMapped] from both the properties and added migration, in this case, its returning proper value. But It will add two columns in MainTable. It's really a BAD design.

So my question is how to select columns from multiple tables in the stored procedure in Entity Framework Core.

I'm using EF Core 2.0.

I think there has to be some way to call the stored procedure with using Entity and then map it to any class because select columns from multiple tables using join is a very basic requirement.

I tried the similar solution, but its giving compilation error.

'DatabaseFacade' does not contain a definition for 'SqlQuery' and no extension method 'SqlQuery' accepting a first argument of type 'DatabaseFacade' could be found (are you missing a using directive or an assembly reference?)

Answer 1

The complete idea to get data from a stored procedure is as follows:

1. You need to add an entity that has the same properties as the procedures select query has.
2. Add the entity to your DbContext and Create a migration. Change the code in the Up() and Down() methods of the migration so that it creates the procedure in the database.
3. Now use the FromSql() method to get the data a normal entity data.

Here is some code that can guide you. Suppose you have these entities in your application domain:

1. Student
2. Parent
3. SchoolClass
4. Section
5. Enrollment

Migrations up method

protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropTable(
            name: "StudentDetails");

        migrationBuilder.Sql(
            @"create proc GetStudentDetail
            @ssid int,
            @sectionId int = null
            as
            select Id, name, Gender, RollNumber, Status, Type,
            FatherName, FatherContact, SchoolClass, Section,
            SsId, SectionId, EnrollmentId
            from 
            (
                SELECT stu.Id, stu.name, stu.Gender, en.RollNumber, en.Status, en.Type,
                p.FatherName, p.FatherContact, sc.Name as SchoolClass, sec.Name as Section,
                ss.SessionId as SsId, sec.Id as SectionId, en.Id as EnrollmentId,
                en.EntryDate, row_number() over (partition by studentid order by en.entrydate desc) as rowno
                from SchoolSessions ss
                join SchoolClasses sc on ss.SessionId = sc.ssid
                join Sections sec on sc.Id = sec.ClassId
                join Enrollments en on sec.id = en.SectionId
                join Students stu on en.StudentId = stu.Id
                join parents p on stu.ParentId = p.Id 
                where ss.SessionId = @ssid 
            ) A
            where rowno = 1 and
            (SectionId = @sectionId or @sectionId is null)"
            );
    }

Migrations down method

protected override void Down(MigrationBuilder migrationBuilder)
    {

        migrationBuilder.Sql("drop proc GetStudentDetail");

        migrationBuilder.CreateTable(
            name: "StudentDetails",
            columns: table => new
            {
                Id = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
                EnrollmentId = table.Column<int>(nullable: false),
                FatherContact = table.Column<string>(nullable: true),
                FatherName = table.Column<string>(nullable: true),
                Gender = table.Column<int>(nullable: false),
                Name = table.Column<string>(nullable: true),
                RollNumber = table.Column<string>(nullable: true),
                SchoolClass = table.Column<string>(nullable: true),
                Section = table.Column<string>(nullable: true),
                SectionId = table.Column<int>(nullable: false),
                SsId = table.Column<int>(nullable: false),
                Status = table.Column<int>(nullable: false),
                Type = table.Column<int>(nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_StudentDetails", x => x.Id);
            });
    }

The fake entity: All properties in this entity are coming from the above-said entities. You can call it a fake entity.

public class StudentDetail
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Gender Gender { get; set; }
    public string RollNumber { get; set; }
    public StudentStatus Status { get; set; }
    public StudentType Type { get; set; }
    public string FatherName { get; set; }
    public string FatherContact { get; set; }
    public string SchoolClass { get; set; }
    public string Section { get; set; }
    public int SsId { get; set; }
    public int SectionId { get; set; }
    public int EnrollmentId { get; set; }
}

Service layer to get data

public IEnumerable<StudentDetail> GetStudentDetails(int ssid)
    {
        var ssidParam = new SqlParameter("@ssid", ssid);
        var result = _appDbContext.StudentDetails.FromSql("exec GetStudentDetail @ssid", ssidParam).AsNoTracking().ToList();
        return result;
    }