"CS0162: Warning as Error: Unreachable code detected" on Razor View - asp.net-mvc

Question

I have the following code within a script tag on my razor view:
self.regions = [];
#foreach(var region in Model.OperationRegions)
{
<text>
self.regions.push({
regionid: '#region.Region_Id',
regionname: '#region.Title',
selected: ko.observable(#(Model.RegionsList.Contains(region.Region_Id).ToString().ToLower()))
});
</text>
}
self.categories = [];
#foreach(var category in Model.Categories)
{
<text>
self.categories.push({
categoryid: '#category.Category_Id',
title: '#category.Title'
});
</text>
}
For clarity, the code outside of the foreach loops and within the text tags are Javascript and the purpose of the razor code is to populate my Javascript arrays with data from the server.
When I run this I am currently getting a server error saying "CS0162: Warning as Error: Unreachable code detected"
The error is thrown on the second "foreach" in the snippet.
Surprisingly I couldn't find another question referring to this error message on an MVC razor page so I'm posting this here.
My question is why is that line of code considered to be unreachable? I will update this question if I find anything else on my page to be relevant to the issue as I try to debug.

Answer 1

The error has disappeared now. I had renamed a property of my model and not recompiled before trying to load the page again. Recompiling made the error go away. I have no idea how the root cause translated to the error message shown but its fixed now in any case.

Answer 2

This is an extremely poor way to handle this. There's no need to build an array piece by piece like this. Just convert your list to JSON.
self.regions = #Html.Raw(Json.Encode(Model.OperationRegions.Select(region => new {
regionid = region.Region_Id,
regionname = region.Title,
selected = Model.RegionsList.Contains(region.Region_Id)
})));
The only thing this can't handle is making selected an observable. However, you can simply loop through the array and fix this:
for (var i = 0; i < self.regions.length; i++) {
self.regions[i].selected = ko.observable(self.regions[i].selected);
}
However, the better approach is to use another view model:
var OperationRegionViewModel = function (data) {
var self = {};
self.regionid = ko.observable(data.regionid);
self.regionname = ko.observable(data.regionname);
self.selected = ko.observable(data.selected);
return self;
};
Then, you can just do something like:
var regions = #Html.Raw(Json.Encode(Model.OperationRegions.Select(region => new {
regionid = region.Region_Id,
regionname = region.Title,
selected = Model.RegionsList.Contains(region.Region_Id)
})));
self.regions = $.map(regions, new OperationRegionViewModel);
Or, even better build your JSON all at once:
var json = #Html.Raw(Json.Encode(new {
regions = Model.OperationRegions.Select(r => new { ... }),
categories = Model.Categories.Select(c => new { ... }),
// etc
});
Then, inject this all into your view model:
var viewModel = (function (json) {
// other stuff
self.regions = $.map(json.regions, new OperationRegionViewModel);
self.categories = $.map(json.categories, new CategoryViewModel);
// etc
})(json);