问题
I have a razor view where I am declaring a string array
@{
var siteList = new List<string>();
var stockTypeList = new List<string>();
}
There is an event on a multiselect that iterates over the selected values and I want to add the value of each of the selected items to this array
$('#stockTypeArea select :selected').each(function (i, selected) {
@stockTypeList.Add(selected.val());
});
Currently this complains that it cannot resolve the 'selected' value. So my question is how can I add these string values to my string array?
The reason I need the string array is that I post this back as part of a @Html.Action
@HTML.Action("CustomReport_Data", "Reports", new { stockCodesList = stockTypeList })))
Perhaps there is a better way to capture this list of strings and pass back to the controller.
Even when I try and test the add method to my string array with:
@stockTypeList.Add("Test");
I get an error that:
Expression must return a value to render
回答1:
Razor code is running server-side.
jQuery is running client-side, and so is your event handler.
This:
$('#stockTypeArea select :selected').each(function (i, selected) {
@stockTypeList.Add(selected.val());
});
Is a mix of both, but that can't ever work. selected.val() is client-side, @stockTypeList.Add(...) is server-side.
All of this explains your first error message.
@stockTypeList.Add("Test"); is also a Razor (server-side) statement. It adds a string to your list, but the method doesn't return a value (public void Add(T item)). the @ Razor operator takes the following expression and writes it as a URL encoded string to the client document, but you're not providing it a legal value (void).
This explains your second error.
@HTML.Action(...) generates a link with a url that can include query string parameters. These are normally coming from the 3rd argument in your call:
@HTML.Action("CustomReport_Data", "Reports", new { stockCodesList = stockTypeList })))
But at the time you execute this code (server-side) the list is of course empty.
You need to collect your string in client-side code (JavaScript array for example) and construct a URL for navigation using these strings.
来源：https://stackoverflow.com/questions/33126759/add-item-to-string-array-in-razor-view