I'm trying to convert an object to a dto

public class topology
{
    public int a { get; set; } 
    public int b { get; set; }
}

to

public class topologyDto
{
    public int a { get; set; }
    public List<int> b { get; set; }
}

What I have right now that is mapping doesn't convert it to a list:

public IEnumerable<topologyDto> GetTopology()
{
     return _dataProvider.GetTopology()
     .Select(x => new topologyDto
     {
        a= x.a,
        b= x.b
     };
}

A test set would look something like this, where I want to map to the topologyDto:

var data = new []
{
    new topology() { a = 1, b = 1 },
    new topology() { a = 1, b = 2 },
    new topology() { a = 1, b = 3 },
    new topology() { a = 1, b = 4 },
    new topology() { a = 2, b = 1 },
    new topology() { a = 2, b = 2 },
    new topology() { a = 2, b = 3 },
    new topology() { a = 2, b = 4 },
};

var test = new []
{
    new topologyDto() { a = 1, b = new List<int>() { 1, 2, 3, 4 }, },
    new topologyDto() { a = 2, b = new List<int>() { 1, 2, 3, 4 }, },
}

CodePudding user response：

Looks like you want to group by a:

_dataProvider.GetTopology()
    .GroupBy(x => x.a)
    .Select(g => new topologyDto
        {
            a = g.Key,
            b = g.Select(t => t.b).ToList(),
        } );