如何从datalist代表id删除图像？

Question

I want to delete image from datalist on the behalf of id but this code is not working Error:Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

public void show_top_one()
{
    BusinessLogic b1 = new BusinessLogic();
    string query = "select txt_img_name from tbl_gallery2";
    DataSet ds = b1.GetDataSet(query);
    DataList1.DataSource = ds.Tables[0];
    DataList1.DataBind();
}

protected void DataList1_DeleteCommand(object source, DataListCommandEventArgs e)
{
    BusinessLogic b1 = new BusinessLogic();
    int id = Convert.ToInt32(DataList1.DataKeys[e.Item.ItemIndex]);
    string query = "Delete from tbl_gallery2 where id='"+id+"'";
    b1.ExecuteQuery(query);
    show_top_one();

}

}

Answer 1

Please change your select query.

string query = "select id,txt_img_name from tbl_gallery2";

and now please add DataKeyName to your datalist like

<asp:DataList DataKeyField="id"

So this will add Id column to datakey. Then you can get value of it in backend.

Answer 2

Try This : You missed .Value, i guess.

protected void DataList1_DeleteCommand(object source, DataListCommandEventArgs e)
{
    BusinessLogic b1 = new BusinessLogic();
    int id = Convert.ToInt32(DataList1.DataKeys[e.Item.ItemIndex].Value);
    string query = "Delete from tbl_gallery2 where id='"+id+"'";
    b1.ExecuteQuery(query);
    show_top_one();

}

Answer 3

don't need single quotations, if it is int

 string query = "Delete from tbl_gallery2 where id="+id;

and also you need to select id column in your select query as well as data key

Answer 4

Ok your code is not giving me a lot of info to work on but if you have you DataSet configured right then you could write a method to: 1. get the image by id. 2. delete the selected image.

 public "classname where the image is" GetById(int id)
    {
        return ds.Find(id);  //ds is your DataSet
    }

and after finding it

 public void Delete(int id)
    {
        var entity = this.GetById(id);
        if (entity!=null)
        {
            this.Delete(entity);
        }
    }

This should be a clean and nice answer :)

Good luck!

Answer 5

First of all you need to check this value

 DataList1.DataKeys[e.Item.ItemIndex].Value

You might be getting null value in the above parameter. If yes you may not have set the data-key-filed in your data-list.

So you will need to set the DataKeyField in your DataList first and then use the code.