Dapper.net how to create a map

asp.net-mvc-4 dapper

Question

 public CodeCustomMapper()
  {

    Map(f => f.Name).Column("SName");
    Map(f => f.Name).Column("TName");
    Map(f => f.EmailID).Column("wmail");
    Map(f => f.EmailID).Column("Email");
   }

I want create this kind of map for dapper.query function.
Please can anybody help?
I want to map custom column names to entity property names.


public class EntityBase
{
    public string CreatedBy { get; set; }
    public DateTime CreatedOn { get; set; }
}

public class Person :EntityBase
{
    public string SecurityAlias{ get; set; }
    public DateTime Identifier{ get; set; }
}

public class EntityBaseMap
{
    public EntityBaseMap()
    {
        var map = new CustomTypeMap<EntityBase>();
        map.Map("CreatingPerson", "CreatedBy");
        map.Map("CreatedDate", "CreatedOn");
        SqlMapper.SetTypeMap(map.Type, map);
    }
}

public class PersonMap
{
    public PersonMap()
    {
        var map = new CustomTypeMap<Person>();
        map.Map("security_alias", "SecurityAlias");
        map.Map("Id", "Identifier");
        SqlMapper.SetTypeMap(map.Type, map);
    }
}

When I call this:

EntityBaseMap entityBaseMap = new EntityBaseMap();
PersonMap personMap = new PersonMap();

now if I use Person entity it's not mapping EntityBase properties inside the person entity.

Accepted Answer

Basically, you need to write an ITypeMap and IMemberMap implementation, which internally could be based on any rules you choose (naming conventions such as removing S etc identifiers, underscores, etc; attributes; or custom maps as in your case).

Here's a complete runnable example that may help:

using Dapper;
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Reflection;

class SomeType
{
    public string Bar { get; set; }
    public int Foo { get; set; }
}

static class Program
{
    static Program()
    {
        // only need to do this ONCE
        var oldMap = SqlMapper.GetTypeMap(typeof(SomeType));
        var map = new CustomTypeMap(typeof(SomeType), oldMap);
        map.Map("IFoo", "Foo");
        map.Map("SBar", "Bar");
        SqlMapper.SetTypeMap(map.Type, map);
    }

    static void Main()
    {
        using (var conn = new SqlConnection("Server=.;Database=master;Trusted_Connection=true"))
        {
            conn.Open();

            var row = conn.Query<SomeType>("select 123 as [IFoo], 'abc' as [SBar]").Single();
            Console.WriteLine(row.Foo);
            Console.WriteLine(row.Bar);
        }
    }

    class CustomTypeMap : SqlMapper.ITypeMap
    {
        private readonly Dictionary<string, SqlMapper.IMemberMap> members
            = new Dictionary<string, SqlMapper.IMemberMap>(StringComparer.OrdinalIgnoreCase);
        public Type Type { get { return type; } }
        private readonly Type type;
        private readonly SqlMapper.ITypeMap tail;
        public void Map(string columnName, string memberName)
        {
            members[columnName] = new MemberMap(type.GetMember(memberName).Single(), columnName);
        }
        public CustomTypeMap(Type type, SqlMapper.ITypeMap tail)
        {
            this.type = type;
            this.tail = tail;
        }
        public System.Reflection.ConstructorInfo FindConstructor(string[] names, Type[] types)
        {
            return tail.FindConstructor(names, types);
        }

        public SqlMapper.IMemberMap GetConstructorParameter(
            System.Reflection.ConstructorInfo constructor, string columnName)
        {
            return tail.GetConstructorParameter(constructor, columnName);
        }

        public SqlMapper.IMemberMap GetMember(string columnName)
        {
            SqlMapper.IMemberMap map;
            if (!members.TryGetValue(columnName, out map))
            { // you might want to return null if you prefer not to fallback to the
              // default implementation
                map = tail.GetMember(columnName);
            }
            return map;
        }
    }
    class MemberMap : SqlMapper.IMemberMap
    {
        private readonly MemberInfo member;
        private readonly string columnName;
        public MemberMap(MemberInfo member, string columnName)
        {
            this.member = member;
            this.columnName = columnName;
        }
        public string ColumnName { get { return columnName; } }
        public System.Reflection.FieldInfo Field { get { return member as FieldInfo; } }
        public Type MemberType { get {
            switch (member.MemberType)
            {
                case MemberTypes.Field: return ((FieldInfo)member).FieldType;
                case MemberTypes.Property: return ((PropertyInfo)member).PropertyType;
                default: throw new NotSupportedException();
            }
        } }
        public System.Reflection.ParameterInfo Parameter { get { return null; } }
        public System.Reflection.PropertyInfo Property { get { return member as PropertyInfo; } }
    }
}



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Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow
Is this KB legal? Yes, learn why