SqlEmbeddedAttribute Class

.NET Standard 2.x

Specifies that a property of the model class will use the specified raw SQL SELECT statement to load data.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Inheritance Constructor

System.Attribute

Syntax

   [AttributeUsage(AttributeTargets.Property)]
   public class SqlEmbeddedAttribute : Attribute, ISqlEmbedded

Constructors

Name	Description
SqlEmbeddedAttribute(string rawSql)	Initializes a new instance of the SqlEmbeddedAttribute class.

Properties

Name	Return Type	Description
ParamValue	string	Gets or sets the value of the parameter that is required when loading the data for the current property.
RawSql	string	Gets the raw SQL SELECT statement that will be used to load the data for the current property.

Examples

The following code example demonstrates how to use the SqlEmbedded attribute. When a property in the model is applied with the SqlEmbedded attribute, it indicates the value of that property comes from a SQL query.

Model: PersonSqlEmbedded

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using SnapObjects.Data;

namespace Appeon.ApiDoc.Models.School
{

    [Table("Person", Schema = "dbo")]
    public class PersonSqlEmbedded
    {
        [Key]
        public int PersonID { get; set; }

        public string LastName { get; set; }

        public string FirstName { get; set; }

        public DateTime? HireDate { get; set; }

        public DateTime? EnrollmentDate { get; set; }

        public string Discriminator { get; set; }

        [SqlEmbedded("select sum(Grade) from StudentGrade " +
            "where StudentID = @personid", ParamValue = "$PersonID"
           )]
        public decimal? SumGrade { get; set; }

    }
}

Example Method:

using SnapObjects.Data;
using Appeon.ApiDoc.Models.School;
using System;

namespace Appeon.ApiDoc.SqlEmbeddedAttributeExamples
{
    public class SqlEmbeddedAttributeExample
    {
        private SchoolContext _context;

        public SqlEmbeddedAttributeExample(SchoolContext dataContext)
        {
            // Sets the data context.
            _context = dataContext;
        }

        public void Example()
        {
            var mapper = _context.SqlModelMapper;

            // Gets the person record whose PersonID = 2 from the database.
            // IMPORTANT: IncludeAll() must be executed here, otherwise the raw SQL 
            // in SqlEmbedded will not be executed.
            var person = mapper.LoadByKey<PersonSqlEmbedded>(2)
                               .IncludeAll()
                               .FirstOrDefault();

            Console.WriteLine("PersonID: {0}, SumGrade: {1}", person.PersonID,
                person.SumGrade);

            /* The code produces the following output:
            PersonID: 2, SumGrade: 7.50
            */

            /* Internally generated T-SQL:
            
            exec sp_executesql N'SELECT
                [PersonID],
            [LastName],
            [FirstName],
            [HireDate],
            [EnrollmentDate],
            [Discriminator] 
            FROM [dbo].[Person] 
            WHERE ([PersonID] = @p0)',N'@p0 int',@p0=2      
            
            exec sp_executesql N'select sum(Grade) from StudentGrade 
            where StudentID =@personid',N'@personid int',@personid=2
            */
        }
    }
}

Applies to

.NET Standard

2.x