I have a flat object, and it looks like as below

public class Test 
{
   public string Name {get; set;}
   public string Number {get; set;}
   public string Description {get; set;}
   public string Name1 {get; set;}
   public string Name2 {get; set;}
}

and I have the data looks like as below

List<Test> tests = new List<Test>
{
    new Test{ Name = "nameA", Number=8, Description="description", Name1 = "test 1", Name2="test name1" },
    new Test{ Name = "nameB", Number=3, Description="description2", Name1 = "test 2", Name2="test name2" },
    new Test{ Name = "nameC", Number=4, Description="description3", Name1 = "test 3", Name2="test name3" },
};

and I am trying to form an object list that looks like below

I am using the below logic to form a list object but failed to add all objects to that,

List<dynamic> testList = new();

int rowIndex = 1;
foreach (var testDt in tests)
{
    dynamic testData = new ExpandoObject();

    if (rowIndex % 2 != 0)
    {
        testData.Name = testDt.Name;
        testData.Description = testDt.Description;
        testData.Number = testDt.Number;
    }
    else
    {           
        testData.Name1 = testDt.Name1;
        testData.Name2 = testDt.Name2;
    }
    testList.Add(testData);
    rowIndex  ;
}

But this logic is not adding all items to the list if the list has more items and could anyone please let me know where I am wrong with the above code.

Many thanks in advance!!!

CodePudding user response：

Here you go:

List<Test> tests = new List<Test>
{
    new Test{ Name = "nameA", Number = 8, Description = "description", Name1 = "test 1", Name2 = "test name1" },
    new Test{ Name = "nameB", Number = 3, Description = "description2", Name1 = "test 2", Name2 = "test name2" },
    new Test{ Name = "nameC", Number = 4, Description = "description3", Name1 = "test 3", Name2 = "test name3" },
};

var results  = 
    from t in tests
    from r in new []
    {
        new { t.Name, Number = t.Number.ToString(), t.Description, Name1 = "", Name2 = "", },
        new { Name = "", Number = "", Description = "", Name1 = t.Name1, t.Name2, },
    }
    select r;

That gives me:

To use a regular foreach loop this would work:

public class Output
{
    public string Name { get; set; }
    public string Number { get; set; }
    public string Description { get; set; }
    public string Name1 { get; set; }
    public string Name2 { get; set; }
}

var results = new List<Output>();
foreach (var t in tests)
{
    results.Add(new Output() { Name = t.Name, Number = t.Number.ToString(), Description = t.Description, Name1 = "", Name2 = "", });
    results.Add(new Output() { Name = "", Number = "", Description = "", Name1 = t.Name1, Name2 = t.Name2, });
}

I've created a new class rather than use dynamic, as dynamic generally creates more problems than it solves, IMO. I avoid it where possible.

And finally, the equivalent using LINQ's method syntax:

results =
    tests
        .SelectMany(t => new []
        {
            new Output() { Name = t.Name, Number = t.Number.ToString(), Description = t.Description, Name1 = "", Name2 = "", },
            new Output() { Name = "", Number = "", Description = "", Name1 = t.Name1, Name2 = t.Name2, },
        })
        .ToList();

CodePudding user response：

The problem is that you are adding only 1 item to the list for each iterate, however, what you need is to add 2 instead to be able to get the expected result.

You can simply do that as follows.

foreach (var testDt in tests)
{
    dynamic testData1 = new ExpandoObject();
    testData1.Name = testDt.Name;
    testData1.Description = testDt.Description;
    testData1.Number = testDt.Number;
    testList.Add(testData1);

    dynamic testData2 = new ExpandoObject();
    testData2.Name1 = testDt.Name1;
    testData2.Name2 = testDt.Name2;
    testList.Add(testData2);
}