重复输入vb.net

Question

I'm working on a Recipe Book in vb.NET but have a background in PHP. I'm trying to build up functionality to add multiple ingredients to a recipe before its saved.

In PHP I would have an auto complete input and add button. When the add button is pressed the ingredient is added to the list of ingredients (with a hidden field for the ingredient id) then when I post the recipe I would simple loop through the post data and extract the id's like this:

<div id="ingredient-list">
 <div>
  <input type="hidden" name="ingredient[0]" value="32" />
  <span>Potatoes</span>
 </div>
</div>
<div>
 <input type="text" onKeyUp="IngredientSearch(this)" />
 <div id="food-search-results" class="auto-complete"></div>
</div>

foreach($_POST['ingredient'] as $ingredient) {
 recipe.addIngredient($ingredient);
}

However I am unsure how to accomplish such a task in .NET. Currently my add button is causing a post-back to the page (which I don't want) and adding the data to a asp:repeater. Could anyone please point me in the right direction or to a code example please.

On a side note, my next task to allow the user to upload multiple images. Which will function much the same but add a new file input when ever a file is attached to the existing input.

Answer 1

If you are not trying to cause a postback you could either do the button as an html button, or you could put the button and the repeater in an update panel. This would cause a partial postback. This would probably be the better option because I do not think you could update the asp:repeater otherwise.

As Titopo said though, I would suggest either using the list to store the IDs or you could use a dataset to store both the ID and text value in the Viewstate.

On your button click you could do something like this...

        Dim ds As DataSet
        Dim dt As DataTable
        If Not ViewState("Ingredients") Is Nothing Then
            ds = ViewState("Ingredients")
            dt = ds.Tables(0)

            Dim dr As DataRow = dt.NewRow
            dr.Item("IngredientID") = IngredientID' However you would get that.
            dr.Item("Ingredient") = txtIngredient.Text
            dt.Rows.Add(dr)
        Else
            ds = New DataSet
            dt = New DataTable
            dt.Columns.Add(New DataColumn("IngredientID"))
            dt.Columns.Add(New DataColumn("Ingredient"))

            Dim dr As DataRow = dt.NewRow
            dr.Item("IngredientID") = IngredientID' However you would get that.
            dr.Item("Ingredient") = txtIngredient.Text
            ds.Tables.Add(dt)
            ds.Tables(0).Rows.Add(dr)
        End If

        Dim dv As DataView = dt.DefaultView
        dv.Sort = "Ingrediant ASC"
        repIngrediants.DataSource = dv
        repIngrediants.DataBind()         ' -- Bind to your repeater here

        ViewState("Ingredients") = ds

This would store the ID and Text for each ingredient. If you had this in an update panel it would preform smoothly and only load the section with the button, text box, and repeater.

Answer 2

An ASP:Button will always causes a post back. I suggest you to store each ingredient when you press the button, but, if you want to send all of them as POST, you can use the ViewState to store a list of ingredientes.

On the Page_Load event:

If Not Me.IsPostBack Then
  ViewState("Ingredients") = New List(Of Integer)
End If

And in the AddButton OnClick event:

Dim list = CType(ViewState("Ingredients"), List(Of Integer)
list.add(ingredient_id)
ViewState("Ingredients") = list

After this, you can use the For Each statment for extract all the ingredients, form the string and send it as POST variable.