Hi guys,
The premise: Get a dropdownlist's content based on the value selected in the first one. Literal data returns successfully. LINQ queries on a LINQ2SQL Datacontext fail.
Being a total rookie at this MVC/LINQ/jQuery stuff, I battled for HOURS on end trying to figure out what was wrong w/ my understanding of the code. When i hard coded my values, everything worked fine, but as soon as i tried to query a LINQ2SQL datacontext, all sorts of wierd stuff started to happen and, finally, when i duplicated the query results into a new object everything worked again! Forgive my lack of linguistic prowess when it comes to LINQ, but, I think it has to do with the "connectedness" of LINQ2SQL's data. When I create another list representing the queried data, all is well, but if i try to use the queried data itself, jQuery's world falls apart (and without erroring too - which made it hard to figure out).
I would basically like a reference to or an explanation of LINQ2SQL's "connectedness" and how/why it's a problem, especially in these remote/asynchronous calling situations!
See the code below - hope it makes sense & thank you in advance :) Basic Layout:
<script type="text/javascript">
$(document).ready(function() {
$("#CaseTypeCategoryId").change(function() {
$.getJSON("/Cases/CaseNatures", { caseTypeCategoryId: $("#CaseTypeCategoryId option:selected").val() }, function(data) {
$("#CaseNatureId option").remove();
$("#CaseNatureId").fillSelect(data);
});
});
});
</script>
<p>
<label for="CaseTypeCategoryId">Case Type:</label>
<%= Html.DropDownList("CaseTypeCategoryId") %>
</p>
<p>
<label for="CaseNatureId">Case Nature</label>
<select id="CaseNatureId" name="CaseNatureId></select>
</p>
Controller.aspx
Initially it was just a
SelectList() { new ListItem() { Text = "--Select A Case Nature--", Value = "" }}
and it worked just fine! Then I tried
public JsonResult CaseNatures(int caseTypeCategoryId)
{
return this.Json(_caseService.GetCaseNatures(caseTypeCategoryId)
.ToList());
}
This failed - no javascript errors, no compilation issues, couldn't figure it out until i tried dumping the data into a new list manually and i finally settled on:
public JsonResult CaseNatures(int caseTypeCategoryId)
{
List returnList = new List();
returnList.Add(new ListItem() { Text = "--Select A Case Nature--", Value = "" });
_caseService.GetCaseNatures(caseTypeCategoryId)
.ToList()
.ForEach(p => returnList.Add(new ListItem() { Value = p.CaseNatureId.ToString(), Text = p.CaseNatureText }));
return this.Json(returnList);
}