APRess ASP.NET MVC 4 (2)

Adding a business class
e.g., a class in charge of sending email messages to pet owners. Or, a class that creates image thumbnails. In short, any type of processing on the server is handled by business model classes. (Similar to APP_CODE in Web Site Project)
Under Models, add a new folder: Business. And under the folder create a new class: PetManagement.cs.
Create a view model: Picture Model to pass between controller and view:
Then create the view
This line:
adds a anti-forgery token in HTML like this:

This works only when the server side action also has a annotation tag placed on top
(This is the POST Method)
After this you can upload and save the file.
Understand Model Binding
GET request – saved in HttpRequest.QueryString
POST request – saved in HttpRequest.Form
POST/File Upload request — saved in HttpRequest.Files

Model Binding:
1) No manual code is needed to extract the data from the HTTPRequest object.
2) Data type conversion happen automatically.
3) Data can be easily validated

Model Binding is possible thanks to the built-on DefaultModelBinder.
It relies on the “names” of the values – they must be the same as defined in the model object.
Chapter 7 – Data Validation (Page 94)
We have a MessageModel
Now we need a controller. MessageController.

ModelState.AddModelError has two parameters –
(1) specific property from the view model for which the error is generated. Can be empty if this is a generic error.
(2) error description.
Next, create a GET (Form) view:
Now the form is created, but there is no validation checking because there is no data annotation defined in the model and there is no manual checking.
Now we add some manual checking
Now if you submit the form with an empty “From” field, you get this error:
Validate with Data Annotation Benefits:
1) enforced across the whole application, not just a single action.
2) no need to call a method, or do anything to enforce the rule
3) code is much less than coding manually
Other annotation:
[CreditCard] is 15 or 16 digits without spaces
[EmailAddress] is a well-formed email address
[EnumDatatype(typeof(name of enum)] enable a .NET framework enum be mapped to a data column. The value must be of those defined in the enum.
[FileExtension(Extensions=”.jpg,.png,.gif”)] file extension must be in one of them
[Range(min, max)] the value must be in the range.
[RegularExpression(pattern)] must match pattern
[Required] is required field
[StringLength(max)] is max length
[URL] must be a well-formed URL
Once you added the notations, the validation will validate the inputs:
Custom Data Annotations
To create a custom data annotation (for example, [BirthCertificateNumber]) you need to create a class that inherits from ValidationAttribute. Name of the class must end with Attribute.
Create a folder under /Models, used to save all custom annotations.

under the new folder, create a new class: BirthCertificateNumberAttribute.cs.
Then in the MessageModel, add a new property so we can test it:
In the GET form, add the form fields for the new property so we can test the validation
Now you see this form: (new field with the [BirthCertificateNumber] Annotation.
If you enter something that’s not valid for this format, you see this error message (custom validations are performed only on the server side!!!! No javascript validation)
Page 110


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