ccccccmd / Dapper.Contrib

Dapper community contributions - additional extensions for Dapper

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

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" });