Dapper.Contrib - more extensions for dapper


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
    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.


Update methods

Update one specific entity

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

or update a list of entities.


Delete methods

Delete an entity by the specified [Key] property

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

a list of entities


or ALL entities in the table.


Special Attributes

Dapper.Contrib makes use of some optional attributes:

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


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" });