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how to return tuple of primitive data types in dapper

Tags:

c#

mysql

dapper

I have been using dapper for one of my projects and in one case I wanted to return a tuple of primitive data types. (only a single row) Since I used dapper, I really would like to use dapper for this case also. I checked these links but couldn't find a solution

Can I map a result to Tuple in Dapper?

Dapper multiple objects from one row

Using Dapper to map more than 5 types

This is what my code looks like,

Using(_dbTransaction = _dbConnection.BeginTransaction()){

     var command = new CommandDefinition(
                "SELECT ID1,ID2 " +
                "FROM table " +
                "WHERE ID0 = @ID",
                new {ID = 34},_dbTransaction); //34 is just a number

    var dataSet   = _dbConnection.QueryFirst<Tuple<uint, decimal>>(command);

    //assign the retrieved values to properties of orderItem (orderItem is a passed object as a parameter)
    orderItem.Id = dataSet.item1;
    orderItem.ContainerPrice = dataSet.item2; 

}

but this would generate an exception

{"A parameterless default constructor or one matching signature (System.UInt32 Id, System.Decimal ContainerPrice) is required for System.Tuple`2[[System.UInt32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Decimal, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]] materialization"}

It would be a great help if can suggest a method or point out where I went wrong

like image 999
Lahiru Jayathilake Avatar asked Aug 22 '16 04:08

Lahiru Jayathilake


1 Answers

If you want to use a Tuple, you can try this:

    [Test]
    public void TupleTest()
    {
        var result = _connection.Query<int, decimal, Tuple<int, decimal>>
            ("select 1 as Id, 12.99 as ContainerPrice", Tuple.Create, splitOn: "*")
            .FirstOrDefault();

        Assert.That(result.Item1, Is.EqualTo(1));
        Assert.That(result.Item2, Is.EqualTo(12.99));
    }

You can also avoid Tuples, and use a dynamic:

    [Test]
    public void DynamicTest()
    {
        var result = _connection.Query<dynamic>
            ("select 1 as Id, 12.99 as ContainerPrice")
            .FirstOrDefault();

        Assert.That(result.Id, Is.EqualTo(1));
        Assert.That(result.ContainerPrice, Is.EqualTo(12.99));
    }
like image 92
Void Ray Avatar answered Nov 15 '22 13:11

Void Ray