Develop Reference

Converting MVC Model List to JSLINQ Error

I have three dropdownlist BodyPart, ExamDetail and ExamView and I have complete data set for these lists. I don't need to call controller again and again whenever the dropdown change event call but I want to fetch list from my model's property list. I am using JS Library to apply LINQ Queryto avoid any loops in code.
My Class Architecture is given below:
public class BodyPart
{
public string ID { get; set; }
public string Text { get; set; }
public List<ExamDetail> examdetail { get; set; }
}
public class ExamDetail
{
public string ID { get; set; }
public string Text { get; set; }
public List<ExamView> examview { get; set; }
}
public class ExamView
{
public string ID { get; set; }
public string Text { get; set; }
}
I have proper data in all my list, here is my js code to fetch ExamDetail Record
var selectedBodyPart = $("#BodyPartDDL").val();
var examdetailList = JSLINQ(#Model.bodypart).Where(function (item) {
return item.ID == selectedBodyPart; });
But I am getting "Uncaught SyntaxError: Unterminated template literal(…)" error where I pass my model list. I need to pass this examdetailList to my ExamDetail partial view. Thank you.

How to represent the value reference to my lookup data in my ViewModel?

I have a list of (for example) countries in my database, which might have a class representation that looks like;
public class Country {
public int CountryId { get; set; }
public string CountryName { get; set; }
}
Now i have a ViewModel class that models a Student for example, and it looks like;
public class StudentViewModel {
public int StudentId { get; set; }
public string StudentName { get; set; }
public int Age { get; set; }
}
When i want to provide the Country the Student comes from, i usually include the following properties in the StudentViewModel class;
public int CountryId { get; set; }
public string CountryName { get; set; }
Now, i not quite sure if i am doing the right thing because on the client (using javascript), i have to keep the CountryId and CountryName synchronized. The reason i have done it this way for a while is because i used the CountryId property to set the initial value of the dropdownlist and CountryName to show the textual value on a different section of the same form.
I would like to know how other people are handling situations like this?

Unable to send JSON data to MVC controller

I have a JavaScript function that looks as follows:
function exportToExcel() {
$.ajax({
url: "/eBird/ExportToExcel",
data: jsonSightingData,
type: 'POST',
contentType: 'application/json'
});
}
My MVC controller looks like this:
public ActionResult ExportToExcel(List<Entities.MyClass> data)
{
try
{
...
}
catch (System.Exception exception)
{
...
}
MyClass defintion is:
public class MyClass
{
public string comName { get; set; }
public int howMany { get; set; }
public double lat { get; set; }
public double lng { get; set; }
public string locID { get; set; }
public string locName { get; set; }
public bool locationPrivate { get; set; }
public string obsDt { get; set; }
public bool obsReviewed { get; set; }
public bool obsValid { get; set; }
public string sciName { get; set; }
}
The class matches the JSON data coming in exactly. The problem is that when my controller method is called, 'data' is always NULL. My understanding was that the MVC model binder would automatically bind the JSON data to my MyClass list. But it doesn't appear to be working.
Sample JSON is as follows:
[{"comName":"Great Black-backed Gull","lat":42.4613266,"lng":-76.5059255,"locID":"L99381","locName":"Stewart Park","locationPrivate":false,"obsDt":"2014-09-19 12:40","obsReviewed":false,"obsValid":true,"sciName":"Larus marinus"}]

Use a General Object (Like JContainer) to "capture" the incoming data. or even Object if you are not sure what you get.
Then see what you have inside.
I use an external deserializer to convert json back to class. (using .ToString() to make it readable to the serializer)
(try Json.Net)
Also - make sure that the JSON is not converted into Unicode. I've had an issue with that as well.
another remark - I think content type should be application/json.
Read this: SO about json content type

Run Fiddler and capture Json sent to controller. The controller expects a List but looks like you are sending single object. Stuff coming in as null happens to many of us. I'll try and run what you have. Can you also mess with controller and give it just MyClass coming in?

How to select object in dropdown

I have a City class
public class City
{
public int Id { get; set; }
public string Name { get; set; }
public string CountryCode { get; set; }
}
and Ride class.
public class Ride
{
public Guid Id { get; set; }
public City From { get; set; }
public List<City> To { get; set; }
public DateTime DateAndTime { get; set; }
}
What is the best way to load cities, pass it to view, show them in dropdownlists and POST data back to controller? Best would be if I could add more than one City to To column.
I have found Selectize.js but I have no experience with JavaScript. Can I pass to options only JSON etc or could it be a list of cities from database.
Thank you for your time.

You'll need a view model, especially if you want to select multiple cities at once. For example:
public class RideViewModel
{
public Guid Id { get; set; }
public DateTime DateAndTime { get; set; }
public int FromCityId { get; set; }
public List<int> ToCityIds { get; set; }
public IEnumerable<SelectListItem> CityChoices { get; set; }
}
Notice that there's no List<City> property on the view model. Instead, there's ToCityIds which will store the selected id values from the list box and CityChoices which will be used to populate the list box. You can't post full City objects from a list box, only simple types like int. So, on POST you'll use the values from ToCityIds to lookup up the City instances from the database. The same goes for your From property on your entity.
Now, in your controller:
private void PopulateCityChoices(RideViewModel model)
{
model.CityChoices = db.Cities.Select(m => new SelectListItem
{
Value = m.Id,
Text = m.Name
});
}
public ActionResult Create()
{
var model = new RideViewModel();
PopulateCityChoices(model);
return View(model);
}
[HttpPost]
public ActionResult Create(RideViewModel model)
{
if (ModelState.IsValid)
{
// Create new `Ride` and map data over from model
var ride = new Ride
{
Id = Guid.NewGuid(),
DateAndTime = model.DateAndTime,
From = db.Cities.Find(model.FromCityId),
To = db.Cities.Where(m => m.ToCityIds.Contains(m.Id))
}
db.Rides.Add(ride);
db.SaveChanges();
}
// Must repopulate `CityChoices` after post if you need to return the form
// view again due to an error.
PopulateCityChoices(model);
return View(model);
}
Finally in your view change the model declaration to:
#model Namespace.To.RideViewModel
And then add your From select list and To list box:
#Html.DropDownListFor(m => m.FromCityId, Model.CityChoices)
#Html.ListBoxFor(m => m.ToCityIds, Model.CityChoices)
You can use the same choices for both, since they're both selecting cities.

How to use subqueries with Breeze.js

We have two entities, User and Person.
public class User
{
public int Id { get; set; }
public string UserName { get; set; }
public string Password { get; set; }
public int PersonId { get; set; }
public Person Person { get; set; }
}
and
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
Every user has a person, but not every person has a user.
I would like to retrieve all the persons, that aren't assigned to a user.
Is there a way to do this using breeze.js?
I can't find anything on using subqueries with Breeze, but I imagine there should be some sort of 'in' clause or some way to use/make a subquery

Updated post: 11/25/13
As of Breeze 1.4.6, 'any' and 'all' operators are now supported.
Older post
Right now there is no easy way to do this. We do plan to support 'any' and 'all' query filters in the future but we just haven't gotten to it yet. Please vote for this here.
As a workaround, in some scenarios you can query for the value of the foreign key being null or 0 but I don't think that this will work in your case, given your schema.