Dapper official translation Tutorial 1: What Dapper that?

December 20, 2018 16:07:28 Day_and_Night_2017 Reads: 108

What is the Dapper?

Dapper .NET is a simple object mappers, with the king of micro title ORM in speed, and almost as fast as the speed of the original ADO.NET data reader. ORM is an object-relational mapper, which is responsible for mapping between databases and programming languages. Dapper By providing a useful extension method to query the database to extend IDbConnection.

How to use Dapper?

Use Dapper just three steps:

1. Create an object IDbConnecton

2. Write a statement CURD

3. statements are passed to the Execute method as a parameter.

Dapper installation:

Use NuGet command: the Install-Package Penalty for Dapper

Database requirements:

As long as it provides a database Provider's database, you can use Dapper.

Dapper extension method:

string sqlOrderDetails = "SELECT TOP 5 * FROM OrderDetails;";
string sqlOrderDetail = "SELECT * FROM OrderDetails WHERE OrderDetailID = @OrderDetailID;";
string sqlCustomerInsert = "INSERT INTO Customers (CustomerName) Values (@CustomerName);";
using (var connection = new SqlCeConnection("Data Source=SqlCe_W3Schools.sdf"))
{
var orderDetails = connection.Query<OrderDetail>(sqlOrderDetails).ToList();
var orderDetail = connection.QueryFirstOrDefault<OrderDetail>(sqlOrderDetail, new {OrderDetailID = 1});
var affectedRows = connection.Execute(sqlCustomerInsert, new {CustomerName = "Mark"});
Console.WriteLine(orderDetails.Count);
Console.WriteLine(affectedRows);
FiddleHelper.WriteTable(orderDetails);
FiddleHelper.WriteTable( new List<OrderDetail>() { orderDetail });
}

Dapper parameters:

// Anonymous
var affectedRows = connection.Execute(sql,
new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
commandType: CommandType.StoredProcedure);
// Dynamic
DynamicParameters parameter = new DynamicParameters();
parameter.Add( "@Kind", InvoiceKind.WebInvoice, DbType.Int32, ParameterDirection.Input);
parameter.Add( "@Code", "Many_Insert_0", DbType.String, ParameterDirection.Input);
parameter.Add( "@RowCount", dbType: DbType.Int32, direction: ParameterDirection.ReturnValue);
connection.Execute(sql,
parameter,
commandType: CommandType.StoredProcedure);
int rowCount = parameter.Get<int>("@RowCount");
// List
connection.Query<Invoice>(sql, new {Kind = new[] {InvoiceKind.StoreInvoice, InvoiceKind.WebInvoice}}).ToList();
// String
connection.Query<Invoice>(sql, new {Code = new DbString {Value = "Invoice_1", IsFixedLength = false, Length = 9, IsAnsi = true}}).ToList();

Dapper execution results

string sqlOrderDetails = "SELECT TOP 10 * FROM OrderDetails;";
using (var connection = new SqlCeConnection("Data Source=SqlCe_W3Schools.sdf"))
{
var anonymousList = connection.Query(sqlOrderDetails).ToList();
var orderDetails = connection.Query<OrderDetail>(sqlOrderDetails).ToList();
Console.WriteLine(anonymousList.Count);
Console.WriteLine(orderDetails.Count);
FiddleHelper.WriteTable(orderDetails);
FiddleHelper.WriteTable(connection.Query(sqlOrderDetails).FirstOrDefault());
}

Dapper other aids

// Async
connection.QueryAsync<Invoice>(sql)
// Buffered
connection.Query<Invoice>(sql, buffered: false)
// Transaction
using (var transaction = connection.BeginTransaction())
{
var affectedRows = connection.Execute(sql,
new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
commandType: CommandType.StoredProcedure,
transaction: transaction);
transaction.Commit();
}
// Stored Procedure
var affectedRows = connection.Execute(sql,
new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
commandType: CommandType.StoredProcedure);