I am trying to get a List of Main category and Sub Category. But in debug i can see its loading only first level Main category but not loading sub category which is relational database. I have attached .edmx picture to make you sure that relational database is configured properly. LazyLoading false also not works! Any idea?
[ChildActionOnly]
public PartialViewResult _GuestNav()
{
using (var db = new TestWebDbEntities())
{
db.Configuration.LazyLoadingEnabled = false;
var Cat = db.Categories.ToList();
return PartialView("_GuestNav", Cat);
}
}
Lazy loading prevents child entities from being loaded, you need to explicitly tell Entity Framework what you want it to do. For this you use the Include method:
var Cat = db.Categories
.Include(c => c.SubCategories)
.Include(c => c.Products)
.ToList();
Related
I'm working on a dotnet mvc5 application. Here's a function from my api of customer controller
public IHttpActionResult GetCustomers()
{
var customerDtos = _context.Customers.ToList().Select(Mapper.Map<Customer, CustomerDto>);
return Ok(customerDtos);
}
I need to add "TYPEAHEAD" plugin to my application. The video series/instructor I'm following says to make the function code change to
public IHttpActionResult GetCustomers(string query = null)
{
var customersQuery = _context.Customers
.Include(c => c.MembershipType);
if (!String.IsNullOrWhiteSpace(query))
customersQuery = customersQuery.Where(c => c.Name.Contains(query));
var customerDtos = customersQuery
.ToList()
.Select(Mapper.Map<Customer, CustomerDto>);
return Ok(customerDtos);
}
in order to make "TypeAhead" plug in work on my view.
The only problem is previously while creating customers I didn't feel the need to add "MembershipType" class to my customer. So how do I use the new code without MembershipType. Is there any other attribute I can replace it with? Name, ID etc.
.Include(c => c.MembershipType);
essentially means that you also want to include the 'child' collection of MembershipType
See here for more information on Loading Related Entities
For your case, you can simply omit this.
public IHttpActionResult GetCustomers(string query = null)
{
var customersQuery = _context.Customers;
if (!String.IsNullOrWhiteSpace(query))
customersQuery = customersQuery.Where(c => c.Name.Contains(query));
var customerDtos = customersQuery
.ToList()
.Select(Mapper.Map<Customer, CustomerDto>);
return Ok(customerDtos);
}
You don't need to replace it with anything.
customersQuery is then an IQueryable<Customer> which the rest of this code can append Where clause to.
It is not executed against the database until the ToList call.
I've got a method in my controller that returns a List<TreeViewItemModel>() that I'm populating with the correct hierarchy. This seems to serialize correctly, but when I load the Treeview, I don't have any of the hierarchy, just the first level of nodes.
Example:
Each of the above Curricula has 2/3 scenarios underneath that I've verified are getting added as items to the base object when going from curriculum => TreeViewItemModel
Controller:
public JsonResult GetAvailableCurricula(string LocationId)
{
LocationId = "1";
if(LocationId != string.Empty)
{
var results = Logic.GetFilteredCurriculum().Select(c => CurriculumToTreeView(c));
return Json(results, JsonRequestBehavior.AllowGet);
}
else
{
return Json(new List<TreeViewItemModel>(),JsonRequestBehavior.AllowGet);
}
}
private TreeViewItemModel CurriculumToTreeView(CurriculumModel c)
{
var tree = new TreeViewItemModel()
{
Id = c.CurriculumId.ToString(),
Text = c.CurriculumName,
HasChildren = c.Scenarios.Any()
};
if (tree.HasChildren)
{
tree.Items = c.Scenarios.Select(scenario =>
new TreeViewItemModel()
{
Text = scenario.Name,
}
).ToList();
}
return tree;
}
View:
#(Html.Kendo().TreeView()
.Name("AvailableCurricula")
.DataTextField("Text")
.DataSource(source => source
.Read(read => read
.Action("GetAvailableCurricula", "TraineeAssignments")
.Data("filterAvailableCurricula")
)
)
Is there some extra step I need to take to bind the child objects AND the parent, instead of just one level at a time? I have a fairly small set of data that I don't need to reload all that often, so I would was hoping to avoid loading each level individually/on-demand.
In case it's helpful, here's the raw JSON I'm sending from the controller for one of my curricula:
{"Enabled":true,"Expanded":false,"Encoded":true,"Selected":false,"Text":"Operator B","SpriteCssClass":null,"Id":"1","Url":null,"ImageUrl":null,"HasChildren":true,"Checked":false,"Items":[{"Enabled":true,"Expanded":false,"Encoded":true,"Selected":false,"Text":"test 2","SpriteCssClass":null,"Id":null,"Url":null,"ImageUrl":null,"HasChildren":false,"Checked":false,"Items":[],"HtmlAttributes":{},"ImageHtmlAttributes":{},"LinkHtmlAttributes":{}},{"Enabled":true,"Expanded":false,"Encoded":true,"Selected":false,"Text":"Scenario II","SpriteCssClass":null,"Id":null,"Url":null,"ImageUrl":null,"HasChildren":false,"Checked":false,"Items":[],"HtmlAttributes":{},"ImageHtmlAttributes":{},"LinkHtmlAttributes":{}}],"HtmlAttributes":{},"ImageHtmlAttributes":{},"LinkHtmlAttributes":{}}
I believe that the remote data option for the Treeview uses ajax to load the child data, either on demand or at initial load - controlled by the LoadOnDemand option.
The remote data examples in the kendo docs behave that way. That is how I implemented it on a previous project. The full code example includes a treeview as well as a grid.
I want to get all comment with navigation property with Linq query. I disabled lazy loading and proxies in my entities.
public partial class dbCommentEntities : DbContext
{
public dbCommentEntities()
: base("name=dbCommentEntities")
{
this.Configuration.LazyLoadingEnabled = false;
this.Configuration.ProxyCreationEnabled = false;
}
}
And my query code for load from database is
var queryTest = (from c in db.Comments
where c.ParentId == null
orderby c.CommentId descending
select new minicomment {
Title = c.Title,
CommentId = c.CommentId,
Comments1 = c.Comments1}).Skip(skip).Take(take);
Now, if I enable lazy loading and proxy in my dbcontext it is work fine for me. it means get all level navigation...
But this is disable or enable equal false it only load one level for me.
How to get all level navigation when lazy and proxy is false
Thank you.
You have to use Eager Loading.
Good article about Eager Loading.
What is Eager Loading?
When using Eager Loading, the related entities are loaded along with
your target entity set.You use an Include statement in your query to
indicate which related entities you want to bring in.
An example :
return (from owner in Catalog.Owners
where owner.Key == ownerKey
select owner)
.Include(o => o.Credits)
.Include(o => o.Provider)
I have many to many relationship some tables. I am using entity framework.
Reservations >> ApartsToReservations << Aparts
ApartsToReservations include ReservationID and ApartID.
and my delete action below:
public ActionResult DeleteReservation(string resultId)
{
var result = Convert.ToInt32(resultId.Trim());
//just I have reservationID
return View();
}
How can delete reservation?
How can delete reservation?
For example:
[HttpPost] // <- should be a POST action because it's modifying data
public ActionResult DeleteReservation(string resultId)
{
var result = Convert.ToInt32(resultId.Trim());
//just I have reservationID
using (var context = new MyContext())
{
var reservation = new Reservation { ReservationID = result };
context.Reservations.Attach(reservation);
context.Reservations.Remove(reservation);
context.SaveChanges();
}
// ... redirect to Index or something, for example:
// return RedirectToAction("Index");
}
If you already have a context instance as a member of your controller class use this instead of creating a new one in the using block.
The code will also delete the related records in the ApartsToReservations link table because by default the relationships to this table are configured with cascading delete.
I'm not quite sure if this is what you are looking for because it actually doesn't matter if Reservation is involved in the many-to-many relationship you mentioned. It is just the (or one) standard way to delete an entity with DbContext.
If you are looking for something different please try to clarify your question or ask a new one which is clearer.
When I update my model I get an error on a child relation which I also try to update.
My model, say Order has a releationship with OrderItem. In my view I have the details of the order together with an editortemplate for the orderitems. When I update the data the link to Order is null but the orderid is filled, so it should be able to link it, TryUpdateModel returns true, the save however fails with:
InvalidOperationException: The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted.]
My update method:
public ActionResult ChangeOrder(Order model)
{
var order = this.orderRepository.GetOrder(model.OrderId);
if (ModelState.IsValid)
{
var success = this.TryUpdateModel(order);
}
this.orderRepository.Save();
return this.View(order);
}
I tried all solutions I saw on SO and other sources, none succeeded.
I use .Net MVC 3, EF 4.3.1 together with DBContext.
There are a number of code smells here, which I'll try to be elegant with when correcting :)
I can only assume that "Order" is your EF entity? If so, I would highly recommend keeping it separate from the view by creating a view model for your form and copying the data in to it. Your view model should really only contain properties that your form will be using or manipulating.
I also presume orderRepository.GetOrder() is a data layer call that retrieves an order from a data store?
You are also declaring potentially unused variables. "var order =" will be loaded even if your model is invalid, and "var success =" is never used.
TryUpdateModel and UpdateModel aren't very robust for real-world programming. I'm not entirely convinced they should be there at all, if I'm honest. I generally use a more abstracted approach, such as the service / factory pattern. It's more work, but gives you a lot more control.
In your case, I would recommend the following pattern. There's minimal abstraction, but it still gives you more control than using TryUpdateModel / UpdateModel:
public ActionResult ChangeOrder(OrderViewModel model) {
if(ModelState.IsValid) {
// Retrieve original order
var order = orderRepository.GetOrder(model.OrderId);
// Update primitive properties
order.Property1 = model.Property1;
order.Property2 = model.Property2;
order.Property3 = model.Property3;
order.Property4 = model.Property4;
// Update collections manually
order.Collection1 = model.Collection1.Select(x => new Collection1Item {
Prop1 = x.Prop1,
Prop2 = x.Prop2
});
try {
// Save to repository
orderRepository.SaveOrder(order);
} catch (Exception ex) {
ModelState.AddModelError("", ex.Message);
return View(model);
}
return RedirectToAction("SuccessAction");
}
return View(model);
}
Not ideal, but it should serve you a bit better...
I refer you to this post, which is similar.
I assume that the user can perform the following actions in your view:
Modify order (header) data
Delete an existing order item
Modify order item data
Add a new order item
To do a correct update of the changed object graph (order + list of order items) you need to deal with all four cases. TryUpdateModel won't be able to perform a correct update of the object graph in the database.
I write the following code directly using a context. You can abstract the use of the context away into your repository. Make sure that you use the same context instance in every repository that is involved in the following code.
public ActionResult ChangeOrder(Order model)
{
if (ModelState.IsValid)
{
// load the order from DB INCLUDING the current order items in the DB
var orderInDB = context.Orders.Include(o => o.OrderItems)
.Single(o => o.OrderId == model.OrderId);
// (1) Update modified order header properties
context.Entry(orderInDB).CurrentValues.SetValues(model);
// (2) Delete the order items from the DB
// that have been removed in the view
foreach (var item in orderInDB.OrderItems.ToList())
{
if (!model.OrderItems.Any(oi => oi.OrderItemId == item.OrderItemId))
context.OrderItems.Remove(item);
// Omitting this call "Remove from context/DB" causes
// the exception you are having
}
foreach (var item in model.OrderItems)
{
var orderItem = orderInDB.OrderItems
.SingleOrDefault(oi => oi.OrderItemId == item.OrderItemId);
if (orderItem != null)
{
// (3) Existing order item: Update modified item properties
context.Entry(orderItem).CurrentValues.SetValues(item);
}
else
{
// (4) New order item: Add it
orderInDB.OrderItems.Add(item);
}
}
context.SaveChanges();
return RedirectToAction("Index"); // or some other view
}
return View(model);
}