Asp.net MVC source code analysis-model validation (server side) implementation (1)

I. MVC validation usage:

In the Asp.net MVC framework, if you need to add verification to the model object, we can mark all attribute attributes inherited from validationattribute on the model attribute.

For exampleCode, Stringlength/range/compare are inherited from validationattribute class.

  Public   Class Logonmodel
{
[Required]
[Stringlength ( 10 )]
 Public   String Username { Get ; Set ;}

[Required]
[Range ( 5 , 10 )]
 Public   String Password { Get ; Set ;}

[Compare ( "  Newpassword  " , Errormessage = "  The new password and confirmation password do not match.  " )]
 Public   String Confirmpassword { Get ; Set ;}

[Display (name = "  Remember me?  " )]
 Public   Bool Rememberme { Get ; Set ;}
}

In the action, we can call the validatemodel method to verify the model object. If the verification fails, an invalidoperationexception is thrown, and the modelstate. isvalid status is false.

[Httppost]
 Public Actionresult Logon (logonmodel model, String Returnurl)
{
 This. validatemodel (model ); 
 If (Modelstate. isvalid)
{
 If (Membershipservice. validateuser (model. username, model. Password ))
{
Formsservice. signin (model. username, model. rememberme );
If (URL. islocalurl (returnurl ))
{
 Return Redirect (returnurl );
}
 Else 
{
 Return Redirecttoaction ( "  Index  " , "  Home  " );
}
}
 Else 
{
Modelstate. addmodelerror ( "" , "  The user name or password provided is incorrect.  " );
}
}

 //  If we got this far, something failed, redisplay form  
              Return View (model );
}

It should be noted that, if we do not call the model object on the validatemodel method action, it can also be verified by default, because MVC triggers the verification method in the defamodelmodelbinder. bindcomplexelementalmodel method in the object binding phase.

Defaultmodelbinder. CS

  Internal   Void Bindcomplexelementalmodel (controllercontext, modelbindingcontext bindingcontext, Object Model ){
 //  Need to replace the property filter + model object and create an inner binding context  
 Modelbindingcontext newbindingcontext = createcomplexelementalmodelbindingcontext (controllercontext, bindingcontext, model );

 // Validation  
              If (Onmodelupdating (controllercontext, newbindingcontext )){
Bindproperties (controllercontext, newbindingcontext );
Onmodelupdated (controllercontext, newbindingcontext );
}
}
 Protected   Virtual   Void Onmodelupdated (controllercontext, modelbindingcontext bindingcontext ){
Dictionary < String ,Bool > Startedvalid = New Dictionary < String , Bool > (Stringcomparer. ordinalignorecase );

 Foreach (Modelvalidationresult validationresult In   Modelvalidator. getmodelvalidator (Bindingcontext. modelmetadata, controllercontext). Validate ( Null )){
 String Subpropertyname = createsubpropertyname (bindingcontext. modelname, validationresult. membername );

 If (! Startedvalid. containskey (subpropertyname )){
Startedvalid [subpropertyname] = bindingcontext. modelstate. isvalidfield (subpropertyname );
}

 If (Startedvalid [subpropertyname]) {
Bindingcontext. modelstate. addmodelerror (subpropertyname, validationresult. Message );
}
}
}

Ii. Source Code Analysis of validatemodel Method

Next, let's take a look at how MVC implements the validatemodel method verification.

 1    Protected   Internal  Void Validatemodel ( Object Model ){
 2 Validatemodel (model, Null   /*  Prefix  */ );
 3 }
 4  
 5           Protected   Internal   Void Validatemodel (Object Model, String Prefix ){
 6               If (! Tryvalidatemodel (model, prefix )){
 7                   Throw   New Invalidoperationexception (
 8 String. Format (
 9 Cultureinfo. currentculture,
 10 Mvcresources. controller_validate_validationfailed,
11 Model. GetType (). fullname
 12 )
 13 );
 14 }
 15 }
 16  
 17    Protected   Internal   Bool Tryvalidatemodel ( Object Model ){
18               Return Tryvalidatemodel (model, Null   /*  Prefix  */ );
 19 }
 20  
 21           Protected   Internal   Bool Tryvalidatemodel ( Object Model, String Prefix ){
 22               If (Model = Null ){
 23                   Throw   New Argumentnullexception ( "  Model  " );
 24 }
 25  
 26 Modelmetadata metadata = modelmetadataproviders. Current. getmetadatafortype () => model, model. GetType ());
 27  
 28               Foreach (Modelvalidationresult validationresult In   Modelvalidator. getmodelvalidator (Metadata, controllercontext). Validate ( Null )){
 29 Modelstate. addmodelerror (defaultmodelbinder. createsubpropertyname (prefix, validationresult. membername), validationresult. Message );
 30 }
 31  
 32              Return Modelstate. isvalid;
 33 }

We can see that row 3 MVC calls modelvalidator. getmodelvalidator to obtain the model's validator object. Let's take a look at the implementation of this method, and it returns the compositemodelvalidator object.

 
Public StaticModelvalidator getmodelvalidator (modelmetadata metadata, controllercontext context ){
Return NewCompositemodelvalidator (metadata, context );
}
 

 
Compositemodelvalidator. CS
 

 1    Private   Class Compositemodelvalidator: modelvalidator {
2               Public Compositemodelvalidator (modelmetadata metadata, controllercontext)
 3 : Base (Metadata, controllercontext ){
 4 }
 5  
 6               Public   Override Ienumerable <modelvalidationresult> validate ( Object Container ){
 7                  Bool Propertiesvalid = True ;
 8  
 9                   Foreach (Modelmetadata propertymetadata In Metadata. properties ){
 10                       Foreach (Modelvalidator propertyvalidator In   Propertymetadata. getvalidators (Controllercontext )){
 11                           // Robbin: If modelvalidationresult is returned for validate, the verification fails.  
  12                           Foreach (Modelvalidationresult propertyresult In   Propertyvalidator. Validate (Metadata. Model )){
 13 Propertiesvalid = False ;
 14                               Yield   Return   New Modelvalidationresult {
15 Membername = defamodelmodelbinder. createsubpropertyname (propertymetadata. propertyname, propertyresult. membername ),
 16 Message = propertyresult. Message
 17 };
 18 }
 19 }
 20 }
 21  
 22                  If (Propertiesvalid ){
 23                       Foreach (Modelvalidator typevalidator In Metadata. getvalidators (controllercontext )){
 24                           Foreach (Modelvalidationresult typeresult In Typevalidator. Validate (container )){
 25                               Yield   Return Typeresult;
 26 }
 27 }
 28 }
 29 }
 30 }

 
Let's take a look at the implementation of the method propertymetadata. getvalidators in the above 10th rows. It returns all validator implementations. In addition, in 12 rows, the validate method of these implementations is called for verification.
 

 
Public VirtualIenumerable <modelvalidator> getvalidators (controllercontext context ){
ReturnModelvalidatorproviders. providers. getvalidators (This, Context );
}
 

it calls the getvalidators method of the modelvalidatorproviders. Providers object. The object type is modelvalidatorprovidercollection. Next let's take a look at the implementation of modelvalidatorproviders. Providers

  Public   static   class  modelvalidatorproviders {
  private   static   readonly  modelvalidatorprovidercollection _ providers =  New  modelvalidatorprovidercollection () {
  New  dataannotationsmodelvalidatorprovider (), 
  New  dataerrorinfomodelvalidatorprovider (), 
  New  clientdatatypemodelvalidatorprovider () 
 }; 
  Public   static  modelvalidatorprovidercollection providers {
  Get {< br>  return  _ providers; 
}< BR >}< br> 
}

This object contains three validatorproviders by default during initialization. here we need to pay attention to dataannotationsmodelvalidatorprovider, which provides all the default system validation rules (except remoteattribute ).

Next, we will analyze in detail the implementation of dataannotationsmodelvalidatorprovider and the design pattern used.

 

Reprinted please indicate the source: http://www.cnblogs.com/RobbinHan/archive/2011/12/15/2289228.html 

Author: November rain http://www.cnblogs.com/RobbinHan