DistinctAttribute Class

.NET Standard 2.x

Specifies that a model class should remove the duplicate values when loading data.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Inherited Constructors

System.Attribute

Syntax

   [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
   public class DistinctAttribute : Attribute

Constructors

Name	Description
DistinctAttribute()	Initializes a new instance of the DistinctAttribute class.

Remarks

The Distinct attribute is the equivalent to adding DISTINCT to the SQL SELECT statement. It removes duplicate values.

Examples

The following code example demonstrates how to use the Distinct attribute. It applies the Distinct attribute to the PersonDistinct class to add DISTINCT to the SQL SELECT statement.

Model: PersonDistinct

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

namespace Appeon.ApiDoc.Models.School
{
    /// <summary>
    /// This model class maps to the dbo.Person table.
    /// The Distinct attribute will filter the duplicate records when doing the data query.
    /// </summary>
    [Table("Person", Schema = "dbo")]
    [Distinct]
    public class PersonDistinct
    {
        public string LastName { get; set; }

    }
}

Example Method:

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

namespace Appeon.ApiDoc.DistinctAttributeExamples
{
    public class DistinctAttributeExample
    {
        private SchoolContext _context;

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

        public void Example()
        {
            // Gets the SQL statement.
            string sql = ModelSqlBuilder.GetBuilder<PersonDistinct>(_context).QuerySql;

            var names = _context.SqlExecutor.Select<PersonDistinct>(sql);

            Console.WriteLine("SQL statement:");
            Console.WriteLine(sql);

            /* This code example produces the following output:
            
            SQL statement:
            SELECT
             DISTINCT [LastName]
            FROM [dbo].[Person]
            */
        }
    }
}

Applies to

.NET Standard

2.x