Save values in list after click event

Question

When I click on this LinkButton I need to save the object on my list, but if I click again, my list will lost the older value and get list count = 1, any suggestion ?

 List<Product> products = new List<Product>();

 protected void AddProduct_Click(object sender, EventArgs e)
    {
        int productID = Convert.ToInt32((sender as LinkButton).CommandArgument); /*Pega o id do button que foi clicado relativa a reserva*/

        products.Add(ProductBLL.GetProductByID(productID));

        ViewState["products"] = products;
    }

This is ASP.NET Web Forms? Please remember to tag your question for the appropriate framework in the future. — mason
– mason, Commented Dec 5, 2018 at 16:29
You're storing the list in ViewState, but when you next add it, you're using a new List. Don't declare a field (class level variable). Instead, use a local variable, retrieve the list from ViewState (if it exists), and add your item to it. — mason
– mason, Commented Dec 5, 2018 at 16:30
Your products variable very likely does not persist between sessions. As mason suggested, you need to retrieve your list from the ViewState, not start a new list. — Robert Harvey
– Robert Harvey, Commented Dec 5, 2018 at 16:30

mason · Accepted Answer · 2018-12-05 16:42:56Z

1

I was able to solve the problem by retrieving the list from ViewState if it exists, then adding my item to it.

protected void AddProduct_Click(object sender, EventArgs e)
{
    List<Product> products = new List<Product>();
    if(ViewState["products"] != null)
    products = (List<Product>) ViewState["products"];

    int productID = Convert.ToInt32((sender as LinkButton).CommandArgument); 

    products.Add(ProductBLL.GetProductByID(productID));

    ViewState["products"] = products;
}

edited Dec 5, 2018 at 16:42

mason

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answered Dec 5, 2018 at 16:37

JNeves

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