所以我有一个列表框在我的页面和一些文本框。通过文本框我可以添加一个项目到我的列表框中(点击按钮,它将它添加到一个私人列表中,然后将其设置为ViewState,并且该列表再次是数据绑定)。我的列表框也位于按钮的Click事件触发的updatepanel中。问题:我的Viewstate在回发中保持为空,因此每次都会重置。Viewstate null on postback
一些代码:
private const string VIEW_INGREDIENTS = "IngredientsList";
private const string VIEW_LANGUAGE = "CurrentLanguage";
private List<IngredientData> _ingredientsList;
protected void Page_PreInit(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
if (ViewState[VIEW_INGREDIENTS] != null)
{
_ingredientsList = (List<IngredientData>) ViewState[VIEW_INGREDIENTS];
}
}
else
{
// prepare ingredient lists
_ingredientsList = new List<IngredientData>();
}
}
protected void Page_Load(object sender, EventArgs e)
{
lstIngredients.DataSource = _ingredientsList;
lstIngredients.DataTextField = "Text";
lstIngredients.DataValueField = "Name";
lstIngredients.DataBind();
}
protected void btnAddIngredient_Click(object sender, EventArgs e)
{
_ingredientsList.Add(new IngredientData { Name = txtIngredientName.Text, Quantity = txtUnitQuantity.Text, Unit = lstUnits.SelectedValue });
ViewState[VIEW_INGREDIENTS] = _ingredientsList;
lstIngredients.DataSource = _ingredientsList;
lstIngredients.DataBind();
}
这似乎解决了它!谢谢! – Fverswijver 2011-06-09 10:02:24
+1真棒,不敢相信我忽略了:D – Andomar 2011-06-09 10:24:22
哇,很高兴知道 – Jim109 2015-11-16 18:44:14