Dapper.Contrib - a simple object mapper for .Net

Release Notes

Located at dapperlib.github.io/Dapper.Contrib

Packages

MyGet Pre-release feed: https://www.myget.org/gallery/dapper

Package	NuGet Stable	NuGet Pre-release	Downloads	MyGet
Dapper.Contrib

Features

Dapper.Contrib contains a number of helper methods for inserting, getting, updating and deleting records.

The full list of extension methods in Dapper.Contrib right now are:

T Get<T>(id);
IEnumerable<T> GetAll<T>();
int Insert<T>(T obj);
int Insert<T>(Enumerable<T> list);
bool Update<T>(T obj);
bool Update<T>(Enumerable<T> list);
bool Delete<T>(T obj);
bool Delete<T>(Enumerable<T> list);
bool DeleteAll<T>();

For these extensions to work, the entity in question MUST have a key property. Dapper will automatically use a property named "id" (case-insensitive) as the key property, if one is present.

public class Car
{
    public int Id { get; set; } // Works by convention
    public string Name { get; set; }
}

If the entity doesn't follow this convention, decorate a specific property with a [Key] or [ExplicitKey] attribute.

public class User
{
    [Key]
    int TheId { get; set; }
    string Name { get; set; }
    int Age { get; set; }
}

[Key] should be used for database-generated keys (e.g. autoincrement columns), while [ExplicitKey] should be used for explicit keys generated in code.

Get methods

Get one specific entity based on id

var car = connection.Get<Car>(1);

or a list of all entities in the table.

var cars = connection.GetAll<Car>();

Insert methods

Insert one entity

connection.Insert(new Car { Name = "Volvo" });

or a list of entities.

connection.Insert(cars);

Update methods

Update one specific entity

connection.Update(new Car() { Id = 1, Name = "Saab" });

or update a list of entities.

connection.Update(cars);

Delete methods

Delete an entity by the specified [Key] property

connection.Delete(new Car() { Id = 1 });

a list of entities

connection.Delete(cars);

or ALL entities in the table.

connection.DeleteAll<Car>();

Special Attributes

Dapper.Contrib makes use of some optional attributes:

• [Table("Tablename")] - use another table name instead of the (by default pluralized) name of the class

  [Table ("emps")]
  public class Employee
  {
      public int Id { get; set; }
      public string Name { get; set; }
  }

• [Key] - this property represents a database-generated identity/key

  public class Employee
  {
      [Key]
      public int EmployeeId { get; set; }
      public string Name { get; set; }
  }

• [ExplicitKey] - this property represents an explicit identity/key which is not automatically generated by the database

  public class Employee
  {
      [ExplicitKey]
      public Guid EmployeeId { get; set; }
      public string Name { get; set; }
  }

• [Write(true/false)] - this property is (not) writeable

• [Computed] - this property is computed and should not be part of updates

• [Column("Columnname")] - this property has a different name in the Database

  • Property is called EmployeeId but Column in DB is called employee_id

    public class Employee
    {
        [ExplicitKey]
        [Column("employee_id")]
        public Guid EmployeeId { get; set; }
        public string Name { get; set; }
    }

Limitations and caveats

SQLite

SQLiteConnection exposes an Update event that clashes with the Update extension provided by Dapper.Contrib. There are 2 ways to deal with this.

1. Call the Update method explicitly from SqlMapperExtensions

   SqlMapperExtensions.Update(_conn, new Employee { Id = 1, Name = "Mercedes" });

2. Make the method signature unique by passing a type parameter to Update

   connection.Update<Car>(new Car() { Id = 1, Name = "Maruti" });