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C # Forehead keeps adding the same item to the list

I am having problems with my simple foreach. I am trying to get data from a database into my list.

IList<DeliveredTaskModel> deliveredTaskModel = new List<DeliveredTaskModel>();
// lines of code 

if (materialUsed.Count > 0)
{
    foreach (var material in materialUsed)
    {
        var deliveryModel = new DeliveredTaskModel();
        deliveryModel.Info = materialUsed[0].SubPartCode;
        deliveryModel.Description = materialUsed[0].Description;
        deliveryModel.Qty = materialUsed[0].Qty;
        deliveredTaskModel.Add(deliveryModel);
    }
}

when i set a breakpoint on foreach. I can see that it has 4 different items in materialUsed. however, when I do this foreach it just adds 4x the same item to the grid.

I am assuming it keeps adding the same item, but why? Can someone please explain?

+5


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4 answers


You always get access at index zero. Correction options:

  1. If you are using foreach

    , use:

    foreach (var material in materialUsed)
{
    var deliveryModel = new DeliveredTaskModel();
    deliveryModel.Info = material.SubPartCode;
    deliveryModel.Description = material.Description;
    deliveryModel.Qty = material.Qty;
    deliveredTaskModel.Add(deliveryModel);
}

  2. If you are using an indexer, change to for-loop

    :

    for(int i = 0; i < materialUsed.Count, i++)
{
    var deliveryModel = new DeliveredTaskModel();
    deliveryModel.Info = materialUsed[i].SubPartCode;
    deliveryModel.Description = materialUsed[i].Description;
    deliveryModel.Qty = materialUsed[i].Qty;
    deliveredTaskModel.Add(deliveryModel);
}

  3. Then a custom property initializer would be better:

    foreach (var material in materialUsed)
{
    deliveredTaskModel.Add(new DeliveredTaskModel
    {
        Info = material.SubPartCode,
        Description = material.Description,
        Qty = material.Qty
    });
}

  4. And then using linq you can achieve this with .Select 

    var deliveredTaskModel = materialUsed.Select(material => new DeliveredTaskModel
    {
        Info = material.SubPartCode,
        Description = material.Description,
        Qty = material.Qty
    }).ToList();


I suggest you go with the last option :)

Last comment - your if statement (materialUsed.Count > 0)

is redundant because if the collection is empty it won't go into the loop

+11


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You are referencing the same fixed index in your loop:

deliveryModel.Info = materialUsed[0].SubPartCode;


You need to use a loop variable:

deliveryModel.Info = material.SubPartCode;
+3


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You should use the current item in each iteration of the foreach loop instead of referencing the list. Try the following:

IList<DeliveredTaskModel> deliveredTaskModel = new List<DeliveredTaskModel>();

        if (materialUsed.Count > 0)
        {
            foreach (var material in materialUsed)
            {
                var deliveryModel = new DeliveredTaskModel();
                deliveryModel.Info = material .SubPartCode;
                deliveryModel.Description = material .Description;
                deliveryModel.Qty = material .Qty;
                deliveredTaskModel.Add(deliveryModel);
            }
        }
+2


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IList<DeliveredTaskModel> deliveredTaskModel = new List<DeliveredTaskModel>();
// lines of code 

if (materialUsed.Count > 0)
{
    foreach (var material in materialUsed)
    {
        var deliveryModel = new DeliveredTaskModel();
        deliveryModel.Info = material.SubPartCode;
        deliveryModel.Description = material.Description;
        deliveryModel.Qty = material.Qty;
        deliveredTaskModel.Add(deliveryModel);
    }
}

materialUsed [0] is the first item in your list, and if the number of items you always make in the list is the first you should take the current item "material"

0


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