I have a small application where I am creating a customer
[Authorize]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult CreateCustomer(GWCustomer customer)
{
if (string.IsNullOrEmpty(customer.CustomerName))
{
ModelState.AddModelError("CustomerName", "The name cannot be empty");
}
//...
if (ModelState.IsValid)
{
//insert in db
}
}
My problem is that the GWCustomer object has an Id, which is primary key and cannot be null. This makes the validation framework flag it as an error. But it's not an error, I haven't created the customer yet, and for now is should be null until it gets saved. How do I bypass this? Or fix it?
I never get to insert it in the DB because the ModelState is never valid.
Edit I am using Linq to SQL, and a repository pattern.
This will exclude value from binding, but not validation:
public ActionResult CreateCustomer([Bind(Exclude = "Id")]GWCustomer customer)
Even when validation occurs, you can still correct ModelState by calling:
ModelState.Remove("Id");
It will remove entries related to Id and change ModelState.Valid property to true if only Id was causing errors.
Using data layer objects in view layer is not recommended. You should definitely think about creating dedicated view model, without Id field.
Maybe you have this line in your view:
#Html.HiddenFor(model => model.Id)
Delete it and the view won't send that parameter with the model.
This is why I always say that the ViewModel objects (input and output) should be separated from the Domain Objects.
The input model should be validated in the way you are above; the domain object state should be validated before it gets written to the database (and exceptions thrown if it is somehow invalid).
Related
Just curious on your thoughts or experiences around service layer validation.
I have to process fairly standard validation such as "object with name property doesn't already exist", but I wasn't sure how to return these validation failures back to the controller.
My initial thought was to implement a standard List<ValidationError> but I've seen it done each and every way so was curious the pros/cons of each.
Thanks for any input.
If you go with System.ComponentModel.DataAnnotations entries you can (as you seem to know) decorate your properties with required and many more tags
public class Person
{
[Required(ErrorMessage="object with name property doesn't already exist")]
public string Name { get; set; }
}
although I personally use ViewModels rather than exposing domain mdoels to the view, your controller action can now do something like:
[HttpPost]
public ActionResult SavePerson(Person model)
{
if (ModelState.IsValid)
{
// your model validates - do things
return RedirectToAction("success view here");
}
return View(model);
}
This is one of the standard 'post' handler patterns in MVC. This is the simplest path to getting your object model validating in my opinion.
From there, there are a few other options - your domain object can implement IValidatedableObject and you can yield return the errors (see http://buildstarted.com/2010/09/20/mvc-3s-ivalidatableobject/ as an example).
I'd recommend not mixing the two though, as if you are using dataannotations and have even a single invalid property, the IsValid method on IValidatableObject will not be called.
From there, there's lots you can do with custom validation attributes (the extended version of IsValid seems to give you more flexibility http://msdn.microsoft.com/en-us/library/gg480674%28v=vs.98%29.aspx)
Hope some of the above helps - once you get past the basics there's a lot you can do with it and things like client validation of custom attributes etc. are all fun.
Cheers,
Terry
[edit to add:
After re-reading your post, it may be that you want to only validate at the service layer? If so, I've used the following approach:
public void Setname(string newName)
{
Validator.ValidateProperty(newName, new ValidationContext(this, null, null) { MemberName = "Name" });
Name = newName;
}
obviously your Name property would need a { get; private set; } for this, though you could always add the Validator.ValidateProperty into an extended setter for the public property either.
]
On a new project I'm working on (first time mvc) I've been using the ms code contracts (which throw exceptions) and do all the validation on my domain objects themselves. For things that can't be validated there (such as validations that require database access) I validate in my services and throw exceptions. Additionally like the poster above I have whole separate view models for everything that have data annotations validators on them. The exceptions bubble up and I catch them in the controller and append to the ModelState. There's a lot of overlap with those and the view model validation but it's not much extra effort and allows me to vary the validation per view and yet still have the "core" validations be required.
The book pro asp mvc 2 has another nice way - write a class that inherits Exception and contains a collection of errors. Then you do your validations, add to the collection then throw the exception then he catches it in the controller and copies over to ModelState. This method will let you catch ALL the errors in one exception instead of just one at the service layer.
I am using Entity Framework + SQL Server DB and am using partial classes with DataAnnotations to validate data. For things like Required and Range, this works fine, but I am unable to get the DataType validators to work.
Here is an example of the (custom) annotation:
[DataTypeWholeNumberAttribute(ErrorMessage = "Zip must be a whole number")]
public object Zip{ get; set; }
...and the Controller Code...
[HttpPost]
public ActionResult Edit(NamedInsuredViewModel viewModel)
{
try
{ //breakpoint here (opening squiggly bracket) shows .Zip is already null
if (ModelState.IsValid)
...save, etc...
}
}
And I know what's happening: The DataType of Zip in the database is int, so the default validation is catching that and applying the generic error message "the value [x] is not valid for [FieldName]" before my validator can get to it (to prove this, I also added the same validator to a string field, and it works just fine). What I don't know is, how can I get around that (and no, I can't change the DB to use strings for everything)?
Some suggestions have been offered in this post (http://forums.asp.net/p/1608322/4162819.aspx#4162819), but so far nothing has helped.
Thanks in advance.
PS - is there really no way to validate a primitive DataType without creating a custom Attribute?
I think the error is to pass something called "viewModel" to a Edit Action.
ViewModel is intended for pass data to a view to render it.
When you submit a form the data have to be mapped to a entity not to a viewModel.
[HttpPost]
public ActionResult Edit(YourEntity entity)
{
try
{ //breakpoint here (opening squiggly bracket) shows .Zip is already null
if (ModelState.IsValid)
...save, etc...
}
}
Apply your custom validator to the class. Then pass in your class instance as the parameter for your validator instead of as a string. Then you can perform the validation on the appropriate property regardless of type.
Given following ASP.NET MVC controller code:
[HttpPost]
public ActionResult Create(FormCollection collection)
{
string[] whitelist = new []{ "CompanyName", "Address1", "Address2", ... };
Partner newPartner = new Partner();
if (TryUpdateModel(newPartner, whitelist, collection))
{
var db = new mainEntities();
db.Partners.AddObject(newPartner);
db.SaveChanges();
return RedirectToAction("Details/" + newPartner.ID);
}
else
{
return View();
}
}
The problem is with the Entity Framework 4: the example Partner entity is mapped to a database table with it's fields NOT ALLOWED to be NULL (which is ok by design - they're required).
Unfortunately, invoking TryUpdateModel when some of the properties are nulls produces as many ConstraintExceptions what is not expected! I do expect that TryUpdateModel return false in this case.
It is ok that EF wouldn't allow setting a property's value to null if it should not be, but the TryUpdateMethod should handle that, and add the error to ModelState errors collection.
I am wrong, or somebody screwed up the implementation of TryUpdateModel method?
It's not "screwed up". It's by design. My preferred way of dealing with this is to bind to an edit model rather than directly to an entity. If that's not an option for you, then you can write an associated metadata provider or initialize the properties.
I have a sql server table with 2 fields, ID (primary key) and Name (unique key).
I'm using linq to sql to produce model objects for asp.net MVC from this table.
To perform the model validation I've implemented IDateErrorInfo in a partial class
public partial class Company : IDataErrorInfo
{
private Dictionary<string, string> _errors = new Dictionary<string,string>();
partial void OnNameChanging(string value)
{
if (value.Trim().Length == 0)
{
_errors.Add("Name", "Name is required");
return;
}
}
}
This performs as expected with the Model.IsValid property and Html.ValidationSummary helper.
However, this code is just checking that the newly created Company has a Name that is not blank. I also need to check if the Name has been used by another Company in the table.
I could just call the AddCompany method on my repository and catch the SQLException, but this feels dirty.
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create([Bind(Exclude="ID")] Company companyToCreate)
{
if (!ModelState.IsValid)
{
return View();
}
//Add to the Database
try
{
_companyRepos.AddCompany(companyToCreate);
return RedirectToAction("Index");
}
catch(SQLException ex)
{
return View("do something to show the error inserting");
}
}
Ideally I want the OnNameChanging method in the partial class to perform the unique key check before I try to add the Company.
Any ideas on how I should be doing this? The only thought I've has so far is to create a fresh database connection in the partial class and query the table.
Thanks
One possibility is for the AddCompany method to return a boolean indicating success or failure of the operation.
However, it is customary to catch this type of error before you attempt to add the record. Put a
bool Exists(string companyName)
method in your Company Repository, and use this to catch the error before attempting to add the record.
The reason this is preferable is you know exactly why the failure occurred. Otherwise, you would either have to catch a custom exception or examine a returned error code.
However you slice it, you're going to obviously have to hit the database to get a list of names already in use. Therefore, I would suggest adding a method in your repository that basically just returns an IList<string> or IEnumerable<string> that simply contains all the distinct names in that table in the DB. Then, in your validating method, simply use that method on the repository to get all the unique names, and implement your check there.
On the NerdDinner example of Professional ASP.NET MVC 1.0 there's a method to create a new dinner as copied bellow (page 89 of the free NerdDinner version).
There it checks ModelState.IsValid for true. It seems to check if the model is valid for the database (that is, it catches data type conversions, like dates with invalid format, but not business rules). Is that true?
When submitting the form, if you have an error in the date, ModelState.IsValid will be false and you'll get back an error, but only for the date because AddRuleViolations was never executed. If you remove the check for ModelState.IsValid completely, then you'll get all the errors (due to the exception), including a marking in the date when it is invalid. Then, why is the check for ModelState.IsValid there at all? Am I missing something?
//
// POST: /Dinners/Create
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(Dinner dinner) {
if (ModelState.IsValid) {
try {
dinner.HostedBy = "SomeUser";
dinnerRepository.Add(dinner);
dinnerRepository.Save();
return RedirectToAction("Details", new {id = dinner.DinnerID });
} catch {
ModelState.AddRuleViolations(dinner.GetRuleViolations());
}
}
return View(dinner);
}
ModelState.IsValid tells you if any model errors have been added to ModelState.
The default model binder will add some errors for basic type conversion issues (for example, passing a non-number for something which is an "int"). You can populate ModelState more fully based on whatever validation system you're using.
The sample DataAnnotations model binder will fill model state with validation errors taken from the DataAnnotations attributes on your model.
From the Errata:
ModelState.AddRuleViolations(dinner.GetRuleViolations());
Should be:
ModelState.AddModelErrors(dinner.GetRuleViolations());
Reference: http://www.wrox.com/WileyCDA/WroxTitle/Professional-ASP-NET-MVC-1-0.productCd-0470384611,descCd-ERRATA.html
All the model fields which have definite types, those should be validated when returned to Controller. If any of the model fields are not matching with their defined type, then ModelState.IsValid will return false. Because, These errors will be added in ModelState.
Yes , Jared and Kelly Orr are right.
I use the following code like in edit exception.
foreach (var issue in dinner.GetRuleViolations())
{
ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
}
in stead of
ModelState.AddRuleViolations(dinner.GetRuleViolations());