I am getting the model values to an action in controller and trying to pass the values to another function in another class by setting it to another object . In the line of invoking the second function, the object throws null exception. It doesnt show null in the if condition check either.
Please find code below.
public ActionResult SearchBySecurity(SearchViewModel srchModel)
{
var searchDTO = new VisitorSearchDTO();
//_mapper.Map<SearchViewModel, VisitorSearchDTO>(srchModel,searchDTO);
searchDTO.VisitorFirstName = srchModel.VisitorFirstName;
searchDTO.VisitorContactNumber = srchModel.VisitorContactNumber;
searchDTO.VisitorCompany = srchModel.VisitorCompany;
searchDTO.VisitDate = srchModel.VisitDate;
if (searchDTO != null)
{
var searchResultsDTO = _searchVisitor.SearchForVisitors(searchDTO);
}
ModelState.Clear();
return View("SearchBySecurity",srchModel);
I am guessing you are getting null exception when you are trying to map your models. Are you using AutoMapper? What is _mapper? If AutoMapper, then it might be worth checking your mapping profile code once if you have used any custom (before, after) mappings.
Rest as everyone has suggested, debug your code and state more clearly where the probles is, what you have tried and give clear definition of your types and environment
Thanks Stephen and Jinish for your inputs.
I have managed to solve the issue.
The trouble was in initializing the controller with mapper and service parameters. Default parameter-less constructor was taken up in the code and hence mapper and service objects were not getting initialized. Solved this by proper implementation of interfaces and mapping profiles.
Related
I'm trying to use the built-in laravel's Ioc container to inject a PageManager class inside a Page model and I'm a little lost.
What I'm trying to achieve is something like that:
class Pages extends Eloquent {
public function __construct(PagesManagerInterface $manager, array $attributes = array())
{
parent::__construct($attributes);
$this->manager = new $manager;
}
public function saveToDisk()
{
$this->manager->writeToFile();
}
But I obtain this error:
ErrorException: Argument 1 passed to Pages::__construct() must be an instance of PagesManagerInterface, none given.
I tried to add this in app/start/global.php:
App::bind('Pages',function(){
return new Pages(new PagesManager);
});
But is seems ignored by the framework, and also i don't know how to insert the $attribute array into this declaration.
I'm a little lost so any help is appreciated!
It's not a good idea to overload a model's constructor because new instances can be spawned behind the scenes through various methods, like Model::find().
When that happens, the dependencies you're asking for in your custom constructor aren't being passed in because the Model class isn't aware of them. So, you get that error message.
See the find() method here: http://laravel.com/api/source-class-Illuminate.Database.Eloquent.Model.html#380-397
See this post by Jason Lewis: http://forums.laravel.io/viewtopic.php?pid=47124#p47124
I think that what you need is:
App::bind('PagesManagerInterface',function(){
return new Pages(new PagesManager);
});
This tells Laravel to inject a new Page object everytime it needs an instance of your PagesManagerInterface wich wasn't passed while creating the model.
In Laravel you can use the IoC Container:
public function saveToDisk(){
$managerObject = app()->make('path\to\class\PagesManagerInterface');
$managerObject->writeToFile();
}
I have been looking for quite some time now on this problem.
Here's the deal.
I'm building a website that calls to a Web API to get its data. My Web API uses a library, working with repository pattern. My database model (EF Model-first) was build in the library. In that model I have a base class Pass. Then I have two derived classes, CustomerCard : Pass and Voucher : Pass. My model from EF Designer
I have a method to get all the CustomerCards.
public IQueryable<CustomerCard> GetAllPasses() {
IList<CustomerCard> allCards = new List<CustomerCard>();
var c_cards = context.Passes;
foreach (var c_card in c_cards) {
if (c_card is CustomerCard) {
allCards.Add((CustomerCard)c_card);
}
}
return allCards.AsQueryable<CustomerCard>();
}
In my ApiController, I use this method to get the passes and return them to the website, like this:
[HttpGet]
[Queryable]
public IQueryable<CustomerCard> GetAllPasses(string version) {
return passRepo.GetAllPasses().AsQueryable();
}
My Web API returns JSON format. This is my config to preserve referencing and stuff:
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling =
Newtonsoft.Json.PreserveReferencesHandling.Objects;
json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Serialize;
config.Formatters.Remove(config.Formatters.XmlFormatter);
I'm using IQueryable because I want to be able to page the data on my website. The api method is available at '/api/v1/passes/all'.
Here's the strange part. To test my paging, I call 1 pass per page.
For my first Pass, it works fine. But when I go to my second page, he also gets the correct pass, but the reference to User is gone.
As you can see in my model, the CustomerCard class has a property User. This indicates who owns the customer card.
So this call loads the user from the pass: 'api/v1/passes/all?$top=1'
but when I call to this one, the user instance is NULL: 'api/v1/passes/all?$top=1&$skip=1'.
However, when I call to 'api/v1/passes/all?$top=2', the User for the second pass IS loaded.
So this is where my mind get's blown! I don't get it? Why doesn't the user-reference comes along with the second one? Could it have something to do with the Lazy loading feature of the EF?
EDIT
When I use the extension method Include on context.passes, an error is thrown:
A specified Include path is not valid. The EntityType 'LCS_Model.Pass'
does not declare a navigation property with the name 'User'.
This is because Passes as a dbset, contains CustomerCard as well as Voucher. Is there a way I can tell my context to expect or convert it to a CustomerCard?
Can someone please help me. If you don't understand my question, ask away!
Thanks allready!
EDIT 2
The method on my API controller is now
[HttpGet]
[Queryable]
public IQueryable<CustomerCard> GetAllPasses(string version) {
return context.Passes.Include("User").OfType<CustomerCard>();
}
This gives me my correct items. I have 2 customer cards in my db. Both are from the same user. My API has the user still loaded. The moment my website receives the response, the User property becomes null. My guess is that it's because it is still referencing to the same user from the first element of the array. Is that possible? And if yes, how can I prevent that from happening?
Yes, you need to make sure any related records are included when you do your query. See this for some examples. Secondly... I fail to understand why you are doing all that work with the for loop... That's a lot of absolutely needless and wasted work for the server to do if you want to do any paging. I'm thinking, besides any other filters you might want to apply, your GetAllPasses should look something like this.
public IQueryable<CustomerCard> GetAllPasses() {
return context.Passes.Include(r => r.User);
}
Edit (2): I need to read better. I have to confess, I'm not familiar with type inheritance in EF. I found some things that might work here: table per hierarchy, table per concrete type, and see also also MSDN Queryable.OfType<TResult>. This is a guess, but let's try:
public IQueryable<CustomerCard> GetAllPasses() {
return context.Passes.OfType<CustomerCard>().Include(r => r.User);
}
I'm using a customized method for tracking individual modified properties of an n-tier disconnected entity class. I extracted it from
Programming Entity Framework: DbContext by Julia Lerman and Rowan
Miller (O’Reilly). Copyright 2012 Julia Lerman and Rowan Miller,
978-1-449-31296-1.
The code is:
public void ApplyChanges<TEntity>(TEntity root) where TEntity : class, IObjectWithState {
// bind the entity back into the context
dbContext.Set<TEntity>().Add(root);
// throw exception if entity does not implement IObjectWithState
CheckForEntitiesWithoutStateInterface(dbContext);
foreach (var entry in dbContext.ChangeTracker.Entries<IObjectWithState>()) {
IObjectWithState stateInfo = entry.Entity;
if (stateInfo.State == RecordState.Modified) {
// revert the Modified state of the entity
entry.State = EntityState.Unchanged;
foreach (var property in stateInfo.ModifiedProperties) {
// mark only the desired fields as modified
entry.Property(property).IsModified = true;
}
} else {
entry.State = ConvertState(stateInfo.State);
}
}
dbContext.SaveChanges();
}
The purpose of this method is to let the EF know only a predefined set of entity fields are ready for update in the next call of SaveChanges(). This is needed in order to workaround the entity works in ASP.NET MVC 3 as follows:
on initial page load: the Get action of the controller is loading the
entity object and passing it as a parameter to the view.
The View generate controls for editing 2 of the fields of the entity,
and holds the ID of the record in a hidden field.
When hitting [save] and posting the entity back to the controller all
of the fields excepting the 3 preserved in the view comes with a null
value. This is the default behavior of the MVC binding manager.
If i save the changes back to the database the update query will of course overwrite the non mapped fields with a sentence as follows:
UPDATE non_mapped_field_1 = NULL, ..., mapped_field_1 = 'mapped_value_1', mapped_field_2 = 'mapped_value_2', ... non_mapped_field_n = NULL WHERE ID = mapped_field_3
This is the reason i'm trying to track the fields individually and update only those fields i'm interested in. before calling the custom method with ApplyChanges() i'm adding the list of fields i want to be included in the update to the IObjectWithState.ModifiedProperties list, in order to get a SQL statement as follows:
UPDATE mapped_field_1 = 'mapped_value_1', mapped_field_2 = 'mapped_value_2' WHERE id = mapped_value_3
The problem is, when marking one of the fields as modified in ApplyChanges, i.e.:
entry.Property(property).IsModified = true;
the system is throwing the following exception:
{System.InvalidOperationException: Member 'IsModified' cannot be called for property 'NotifyCEDeadline' on entity of type 'User' because the property is not part of the Entity Data Model.
at System.Data.Entity.Internal.InternalPropertyEntry.ValidateNotDetachedAndInModel(String method)
at System.Data.Entity.Internal.InternalPropertyEntry.set_IsModified(Boolean value)
at System.Data.Entity.Infrastructure.DbPropertyEntry.set_IsModified(Boolean value)
...
So the question is. There's a way to bypass this EF validation or let the context know of the existance of this system property (IsModified) that i'm trying to change?
Summary of the architeture:
EF Code first (annotation + Fluent API)
Oracle .NET EF Data provider (ODAC)
Context is injected to a cutom business context with nInject.MVC => this is the reason i customized the ApplyChanges() method from
using (var context = new BreakAwayContext()){
context.Set().Add(root);
to a simple call to the already initialized dbcontext
dbContext.Set().Add(root);
Oracle Database is created manually i.e. without the help of EF, so no EF metadata tables are used.
Thanks,
Ivan.
Very good description, however I can't find any information on why you need a transient property called "IsModified" in the object and/or why you need to tell EF about it being modified (EF won't be able to persist it anyway).
The value of the IsModified property should be set by the model binder if the property was incldued in the view anyway.
You could just add code in your ApplyChanges method to skip a property named "IsModified", or even better, filter only known properties using entry.CurrentValues.PropertyNames, e.g.:
foreach (var property in stateInfo.ModifiedProperties) {
// mark only the desired fields as modified
if (entry.CurrentValues.PropertyNames.Contains(property)) {
entry.Property(property).IsModified = true;
}
}
Update: Ivan, very sorry I did not understand the problem better when you posted it several months ago and that I did not follow up after your added these clarifying comments. I think I understand better now. That said, I think the code snippet that I offered can be part of the solution. From looking at the exception you are getting again, I understand now that the problem that EF is detecting is that NotifyCEDDealine is not a persistent property (i.e. it is not mapped in the Code First model to a column in the database). IsModified can only be used against mapped properties, therefore you have two options: you change the code of the implementation of IObjectWithState in your entities so that non-mapped properties are not recorded in ModifiedProperties, or you use my code snippet to prevent calling IsModified with those.
By the way, an alternative to doing all this is to use the Controller.TryUpdateModel API to set only the modified properties in your entities.
Hope this helps (although I understand it is very late).
I'm working on an ASP.NET MVC project that will allow users to perform batch edits on the attributes of objects. The implementation is in a sort of "wizard" like form with four phases to the process as follows:
"Select the attributes you want to edit" - the first page will present the user with a list of checkboxes representing each of the attributes they want to edit. The user should check the attributes they wish to edit and select "Continue".
"Edit the selected attributes" - the second page will present the user with a list of distinct "editors" which will be unique for each of the attributes they selected on the first page.
"Review your changes" - this page will allow the user to review the changes they've made to the attributes they selected.
"Submit your changes" - this page will actually submit the information about the edits the user wishes to make to the selected attributes against the selected collection of objects.
Fairly straight-forward.
As I mentioned, the "editor" will be unique to each attribute, and could have any combination of different controls on it. Once a user has made their edits and the application posts that information to the "Review" page is where I'm currently having my problem.
We've developed the concept of an "EditorWorker" class that is unique to each attribute, which is responsible for generating the ViewModel necessary for each editor, but is also responsible for creating/returning (within the "Review" page controller action) an object that is the "model" object for the editor that the post data can be bound to, which can then be use to display the edited data for review. This object should have properties that match up with the IDs of the controls in the editor so that model binding can occur.
I've got the "EditorWorker" creating and returning the class needed, but for some reason, when I call TryUpdateModel and pass in that class, its properties aren't getting populated as a result of that method call as I would expect them to. I have verified that the values are in the posted FormCollection. Below is the code for my controller action where I'm attempting to do this. If someone can help me understand why TryUpdateModel isn't working in this scenario, I would be very appreciative.
[HttpPost]
public virtual ActionResult Review(ReviewBatchViewModel model)
{
var selectedAttributes = GetSelectedAttributes(model.SelectedAttributeIds.Split(',').Select(i => Int64.Parse(i)).ToArray());
var workers = new List<IEditorWorker>();
var reviewData = new Dictionary<ViewAttribute, IEditData>();
foreach (var attribute in selectedAttributes)
{
if (!string.IsNullOrEmpty(attribute.EditorWorker)) // If there is no EditorWorker defined for this object, move on...
{
var worker = ServiceLocator.Current.GetInstance(Type.GetType(string.Format("{0}.{1}", EditorWorkerNamespace, attribute.EditorWorker)));
var attributeEditData = ((IEditorWorker)worker).LoadEditData();
if (TryUpdateModel(attributeEditData))
model.EditData.Add(attributeEditData); // model.EditData is a List<IEditData> that will be iterated on the Review page
reviewData.Add(attribute, attributeEditData);
}
}
return View(model);
}
// ReviewBatchViewModel.cs
public class ReviewBatchViewModel : BaseViewModel
{
public ReviewBatchViewModel() { EditData = new List<IEditData>(); }
public string SelectedAttributeIds { get; set; }
public List<ViewAttribute> SelectedAttributes { get; set; }
public List<IEditData> EditData { get; set; }
}
// IEditData.cs
public interface IEditData
{
}
// BroadcastStatusEditData.cs
public class BroadcastStatusEditData : IEditData
{
public int BroadcastStatus { get; set; }
}
I totally understand that this controller action is incomplete in its current state. I'm presently working on just trying to get those EditData objects populated correctly before I move on. As mentioned, any thoughts would be greatly appreciated. Thanks.
UPDATE: With regards to #mare's comment, I should have explained that part more clearly, sorry. The call to TryUpdateModel actually is returning true, but the fields on the model object being passed into it aren't actually being populated from the values that have been confirmed present in the posted form data. The model object being passed into the call is not a List, its just a poco. The resulting, ultimately hopefully populated model object is then being added to a List collection of model objects that will then be used for displaying the posted data for review on the Review page. I'm not loading anything from a datastore at all. Unique editors for each selected attribute are being rendered to the Edit screen, and I'm attempting to capture the edit values for display on a Review screen prior to submitting the batch of edits to a service. Hopefully that's more clear. Thanks.
UPDATE 2: I've included the definition of the ReviewBatchViewModel class as requested by #mare in the comments. The use of the var keyword in most cases in this code sample is largely due to the fact that the methods that are populating those variables is going to be returning an object of a different type for each attribute selected, so I never know exactly what its going to be at runtime (although it will always implement an interface, in this case either IEditorWorker and/or IEditData). There is a single class in the Model called "Attribute". The provided code sample has three variables relative that class: 1) SelectedAttributeIds is a comma-separated list of the Id's of the attributes that the user has selected to edit, which gets passed from the Edit page to the Review page via hidden field, 2) selectedAttributes is a collection of the actual Attribute objects that correspond to those Ids that I can work with, and 3) attributeEditData is an instance of the IEditData class specific to each given attribute that I'm attempting to bind the posted data from the Edit page to.
Hopefully this additional information clears things up even more.
TryUpdateModel is a generic method, and therefore attempts to infer all type information based on the Generic Type Parameter.
From what I understand in your example above, you are always passing in a IEditData correct?
In effect you are saying:
TryUpdateModel<IEditData>(attributeEditData)
This is most likely the cause for not seeing any properties being set, since IEditData doesn't have any properties ;)
To do what you want you will probably have to create a custom ModelBinder.
As a quick code review side note, your solution seems overly complicated. I had to stare at your solution for a good while just to figure out where to start. Creating a custom model binder may solve your immediate problem, but you might be looking at a big time maintenance headache here. I'm willing to bet there is a simpler approach that will lead to fewer problems down the road.
Based on your comments I have changed the code around from System.Object to your IEditData interface, but everything still holds. I noticed in an earlier comment you mentioned using var because you didn't know the type until runtime. However, there is nothing magic about the var keyword. The only thing it does is give you implicit typing, but it is still statically typed.
The nice thing about MVC is that you can just pop over to Codeplex and have a look at the source for TryUpdateModel if you want. Digging down a few layers you will eventually find a call to this internal method:
protected internal bool TryUpdateModel<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties, IDictionary<string, ValueProviderResult> valueProvider) where TModel : class {
if (model == null) {
throw new ArgumentNullException("model");
}
//valueProvider is passed into this internal method by
// referencing the public ControlerBase.ValueProvider property
if (valueProvider == null) {
throw new ArgumentNullException("valueProvider");
}
Predicate<string> propertyFilter = propertyName => BindAttribute.IsPropertyAllowed(propertyName, includeProperties, excludeProperties);
//Binders is an internal property that can be replaced by
// referencing the static class ModelBinders.Binders
IModelBinder binder = Binders.GetBinder(typeof(TModel));
ModelBindingContext bindingContext = new ModelBindingContext() {
Model = model,
ModelName = prefix,
ModelState = ModelState,
ModelType = typeof(TModel),
PropertyFilter = propertyFilter,
ValueProvider = valueProvider
};
binder.BindModel(ControllerContext, bindingContext);
return ModelState.IsValid;
}
Notice the use of typeof(TModel) everywhere... in your case that is getting translated into typeof(IEditData), which isn't very useful since it is only a marker interface. You should be able to adapt this code for your own use, making sure to use GetType() in order to get the actual type at runtime.
I hope this helps out!
P.S. I've added some comments to the above code to help out a little
#Josh, you were very helpful in helping me understand why TryUpdateModel wasn't working for me, and I appreciate that. Unfortunately, I think the larger issue here was that fact that I (not exactly sure which) was either unable or unwilling to try to document all of the details of the requirements for the problem I'm trying to solve here, which I think made it difficult for anyone to be able to provide much meaningful input. The biggest problem for us is that, because we have no idea until runtime which attributes a user has selected for editing, we don't know which objects we'll be working with in the context of these controller actions, or what their types will be. The one place that we safely can work with known data and types, is within the context of each of the unique EditorWorker objects, which is where I've chosen to do the heavy lifting here.
I was hoping and attempting to take advantage of all of the heavy lifting that MSFT has done for us within the MVC framework to handle model binding, but I've come to the conclusion at this point that I don't think that's going to work for us. The solution that I've come up with at this point, is to allow the LoadEditData method of the EditorWorker classes handle loading up the EditData classes for for me. As each EditorWorker class is unique to, and has knowledge of the attribute that it is associated with. The problem I was having originally was that I was letting the EditorWorker.LoadEditData method just return an empty instance of the specific type of EditData class that I needed for the attribute I was currently working with, and let the MVC framework handle model binding to that object for me. That wasn't working because that method is designed to return an object of type IEditData, and I never really knew exactly what type it was that I was currently working with, so I had no way of specifying the type in the call to either of the typed methods: TryUpdateModel<T> or UpdateModel<T>.
So the solution I've come up with, and am going with at least for now (re-education and/or refactoring may very well change this in the future, who knows) is to just pass the Request.Form object into the call to EditorWorker.LoadEditData and let that method handle actually loading up the EditData object that it knows it needs to return for the attribute it's responsible for, which it can do as it knows what information should be in the posted form collection to load up its EditData object.
So that's where I'm at for now. Thanks for the help.
I am having a weird issue in ASP.NET MVC with objects not being updated with UpdateModel when passed a formCollection. UpdateModel does not appear to be working properly when the object being updated is created through reflection.
Scenario: I have an application which has approximately 50 lookup tables--each of which includes exactly the same schema including typical fields like id, title, description, isactive, and createdon. Rather than build 50 views, I wanted to have a single view which could display the data from all of the lookup tables. I created an Interface called IReferenceEntity and implemented it in each of the POCOs representing my lookup tables.
Using this interface, I am able to easily populate a view with a record from the lookup table. (I pass the items to the view via the following.)
System.Web.Mvc.ViewPage<MyNamespece.IReferenceEntity>
From the database to the view, every thing works perfectly.
However, when I attempt to update the model on post, I am running into some problems.
If I explicitly declare an object reference like the following, every thing works perfectly and the values of my object are updated with the values from my form. Hence, I can then update the database.
AccountStatus a = new AccountStatus();
UpdateModel(a, formCollection.ToValueProvider());
Unfortunately, hard coding the object type would completely defeat the reason for using an interface.
(A primary objective of the application is to be able to dynamically add new tables such as lookup tables without having to do anything "special". This is accomplished by reflecting on the loaded assemblies and locating any classes which implement a specific interface or base class)
My strategy is to determine the concrete type of the object at postback and then create an instance of the type through reflection. (The mechanism I use to determine type is somewhat primitive. I include it as a hidden field within the form. Better ideas are welcome.)
When I create an instance of the object using reflection through any of the following methods, none of the objects are being updated by UpdateModel.
Type t = {Magically Determined Type}
object b = Activator.CreatorInstance(t);
UpdateModel(b, formCollection.ToValueProvider());
Type t = {Magically Determined Type}
var c = Activator.CreatorInstance(t);
UpdateModel(c, formCollection.ToValueProvider());
Type t = {Magically Determined Type}
IReferenceEntity d = Activator.CreatorInstance(t);
UpdateModel(d, formCollection.ToValueProvider());
Note: I have verified that the objects which are being created through relection are all of the proper type.
Does anyone have any idea why this might be happening? I am somewhat stumped.
If I was really "hard up", I could create factory object which would many instantiate any one of these reference entity/lookup objects. However, this would break the application's ability to allow for new lookup tables to be added and discovered transparently and is just not quite as clean.
Also, I could try deriving from an actual ReferenceEntity base class as opposed to an interface, but I am doubtful whether this would make any difference. The issue appears to be with using reflection created objects in the modelbinder.
Any help is appreciated.
Anthony
Augi answered this on ASP.NET forums. It worked with only a couple of minor modifications. Thank you Augi.
The problem is that [Try]UpdateModel methods allow to specify model type using generic parameter only so they don't allow dynamic model type specification. I have created issue ticket for this.
You can see TryModelUpdate method implementation here. So it's not difficult to write own overload:
public virtual bool TryUpdateModelDynamic<TModel>(TModel model, string prefix, string[] includeProperties, string[] excludeProperties, IDictionary<string, ValueProviderResult> valueProvider) where TModel : class
{
if (model == null)
{
throw new ArgumentNullException("model");
}
if (valueProvider == null)
{
throw new ArgumentNullException("valueProvider");
}
//Predicate<string> propertyFilter = propertyName => BindAttribute.IsPropertyAllowed(propertyName, includeProperties, excludeProperties);
IModelBinder binder = Binders.GetBinder( /*typeof(TModel)*/model.GetType());
ModelBindingContext bindingContext = new ModelBindingContext()
{
Model = model,
ModelName = prefix,
ModelState = ModelState,
//ModelType = typeof(TModel), // old
ModelType = model.GetType(),
// new
//PropertyFilter = propertyFilter,
ValueProvider = valueProvider
};
binder.BindModel(ControllerContext, bindingContext);
return ModelState.IsValid;
}
Does your IReferenceEntity contain setters on the properties as well as getters? I would think that the last sample would work if the interface had property setters, though you'd have to cast it to get it to compile.
Type t = {Magically Determined Type}
IReferenceEntity d = Activator.CreatorInstance(t) as IReferenceEntity;
UpdateModel(d, formCollection.ToValueProvider());
Normally the reason that it won't set a property on a class is because it can't find a public setter method available to use via reflection.
Just a quick "another thing to try":
UpdateModel(d as IReferenceEntity, formCollection.ToValueProvider());
Not sure if that will work, and I haven't tried it myself, but it's the first thing that came to mind.
If I get a chance later I'll peek at the Default Model Binder code and see if there's anything in there that is obvious...