What is the difference between declaring #ModelAttribute as a method parameter and using model.asMap()?
Example:
public void method1(#ModelAttribute("attr") MyObject myObj) {
...
}
public void method2(Model model) {
MyObject myObj = (MyObject) model.asMap().get("attr");
}
These are not the same if that's what your thinking. I tried to get an attribute from the model doing it the first way but didn't work so ended up doing it the second way.
Thanks
EDIT: What I mean by "it didn't work" is that when I used #ModelAttribute, it was confusing the values of the variables in that object to another object of a different type which had the same variable names.
EDIT #2: No it is not a duplicate because he does not address the model.asMap() method. As per the other post, I tried using #ModelAttribute on a #SessionAttributes variable but ran into problems so had to use model.asMap()
Related
I have a function under class MyController:
#RestController
#RequestMapping(value = "/api/service")
public class MyController {
#PostMapping(value = "add_person")
public MyResponse addPerson(#RequestBody Person person) {
// ...
}
#PostMapping(value = "add_person_2")
public MyResponse addPerson(#PathVariable(value = "person_age") Int age, #RequestBody Person person) {
// ...
}
}
I have setup AspectJ in my project to have a AOP logic to run whenever those two addPerson(...) method above is called:
#Around("execution(public MyResponse addPerson(..))")
public void around(ProceedingJoinPoint joinPoint) {
// NO matter which addPerson(...) is executing, I am only interested in the
// parameter value annotated with #RequestBody.
// How can I access the parameter that passed in addPerson(...) & is annotated with
// #RequestBody through ProceedingJoinPoint ?
}
My question is mentioned in above code comment. I wonder how can I access the parameter annotated with #RequestBody in my AOP function? I don't want to check parameter type or name, but interested to know how to access parameter by checking the annotation through ProceedingJoinPoint. Is it possible?
I do not want to mark this question as a duplicate because it is no exact duplicate, but my answer here should answer the question about how to
match an annotated parameter at any position,
get the annotation + the parameter value itself.
The linked answer uses a #Before advice. If you want to somehow replace the value by another one in an #Around advice when calling proceed() this is also possible, but was not asked here and my request for seeing more of the advice method body was also ignored.
If you want to limit to annotated Person parameters, you would have to use the fully qualified class name my.package.Person instead of the * inside (*) and do the corresponding cast after accessing the parameter in the advice body.
In my comment I also asked if the parameter has a fixed relative position in the parameter list such as first, last or second/third from left/right. If the OP would have confirmed such a fixed relative position, reflection would not be necessary and the corresponding parameter could be bound to an advice method parameter directly via args() pointcut designator. This would be quite elegant and eliminate the need to loop over getArgs() or over a two-dimensional array of parameter annotations.
i need to do something like this
String myVar = "myString";
...
#Preauthorize("customMethod(myVar)")
public void myMethod() {
...
}
but I'm failing at it. How can I do that? It says it cannot be resolved
EDIT:I'm decoupling few rest services and sometimes I have to share infos between them
#Value("${my-properties}")
String urlIWantToShare;
...
#PreAuthorize("isValid(#myValue,urlIWantToShare)")
#RequestMapping(value = "**/letsCheckSecurityConfig", method = RequestMethod.GET)
public boolean letsCheckSecurityConfig(#RequestHeader(name = "MY-VALUE") String myValue)) {
return true;
}
this "isValid" custom security method will call an external service, that doesn't know anything about the caller and his infos. I need to transmit few infos and I need to take them from different kind of sources
One of the sources is my application.properties
EDIT2: I managed to do this
#PreAuthorize("isValid(#myValue, #myProperty)")
#RequestMapping(value = "**/letsCheckSecurityConfig", method = RequestMethod.GET)
public boolean letsCheckSecurityConfig(#RequestHeader(name = "MY-VALUE") String myValue,
#Value("${my-property-from-app-properties}") String myProperty))
..but I want to use not only actual static properties but runtime one. Any help?
You can create a wrapper method without parameters which will call the desired method with parameters. In the annotation you can use the method without parameters
Apologies if I have misunderstood what you are trying to do, but from my understanding you're trying to set an annotation at runtime based on a variable / app.properties, so that you can then read this variable and then execute your class?
If this is the case, You cannot do this from an annotation alone as annotations cannot read local variables and cannot be set at runtime.
However, one option for you is to have an object which contains the 'values' of interest for you and then read the values from the object.
Something like the below:
PoJo
public class testObject{
#test
private String myVar;
private String myValue;
//Getters and Setters
}
Get Object values
public void getFields (Object obj){
Field fields = obj.getClass().getDeclaredFields();
for (Field f : fields){
test fieldAnnotation = f.getAnnotation(test.Class);
if (fieldAnnotation != null){
f.get(obj);
// Do checks based on this
}
}
}
Main Class
public static void main(String[] args){
//Create object
testObject test = new testObject();
test.setOne("testOne");
test.setTwo("testTwo");
getFields(test);
}
I've pulled this code based on what I had to do to get the fields - but in my case, I did not know the object types I was going to be passed. You are simply using the annotation to 'mark' the fields you want to retrieve and then reading the value from the object.
If you're in a similar situation, then you can see my answer here: initial answer
Let me know if i've misunderstood this and I can try and further clarify my answer.
I have marked a class with #ControllerAdvice
Added a method
#ModelAttribute
public void setSourceAppId(Model model)
{
model.addAttribute("myattribute","1234");
}
But this method is not getting called at all.
I have not yet used modelattribute with a setter method so i cannot tell that thats a wrong approach, but changing it to a getter will do the job. Also, you dont need to add it to the model yourself. Modelattribute is handling exactly that.
#ModelAttribute("myattribute")
public int getSourceAppId()
{
return 1234;
}
Does WebAPI can handle ValidationAttribute on action parameter?
For instance:
public class SampleController : ApiController
{
public string Get([RegularExpression("sampleExpression")]string id)
{
return "result";
}
}
In this sample WebAPI doesn't invoke any methods of RegularExpressionAttribute (or any other data annotation attribute) to validate input parameter. But in case if we passing an object as parameter, for instance a class then WebAPI can validate properties.
Is it a bug? Or I'm doing something wrong?
UPD: It's an open issue:
http://aspnetwebstack.codeplex.com/workitem/24?PendingVoteId=24
Does anyone can suggest a workaround?
This is a genuine question, I'm curious why not just do something like :
public class SampleController : ApiController
{
public string Get(string id)
{
RegularExpressionHelper.ValidateWith("sampleExpression",id);
return "result";
}
}
To me this seems to be equivalently concise. It is obvious when the validation occurs. I can safely assume that if the validation fails then an exception will be thrown. I can easily add additional validation and be confident of the order in which they occur.
Regarding the attribute method, I don't know if the validation is used as part of the route matching, I have no idea what happens if it fails. I don't know what filters run before or after the validation. I'm sure if I knew MVC better I would know the answer to these questions, but I don't see the advantage of using an attribute that makes my code's behaviour dependent on some framework controlled infrastructure.
Am I missing some significant benefit?
I had the same doubt. My workaround consists in creating a class just for encapsulating the parameter, so I can decorate it with the validation attribute I want. I could use the workaround proposed by Darrel in his answer, but I have a filter that checks if ModelState.IsValid before entering the action, so I need to validate before the action gets executed.
[ModelBinder]
public class Item
{
[RegularExpression("sampleExpression")]
public string Id { get; set; }
}
The class must be annotated with [ModelBinder], otherwise the parameter binding mechanism will try to extract the id field from the body of the request. Read this article for more info.
Also, note that Id is now in PascalCase instead of camelCase. Read this article to understand how the conversion is made.
The action signature is:
public string Get(Item item)
I'm working with Spring MVC and I'd like it to bind a a persistent object from the database, but I cannot figure out how I can set my code to make a call to the DB before binding. For example, I'm trying to update a "BenefitType" object to the database, however, I want it to get the object fromthe database, not create a new one so I do not have to update all the fields.
#RequestMapping("/save")
public String save(#ModelAttribute("item") BenefitType benefitType, BindingResult result)
{
...check for errors
...save, etc.
}
There are several options:
In the simpliest case when your object has only simple properties you can bind all its properties to the form fields (hidden if necessary), and get a fully bound object after submit. Complex properties also can be bound to the form fields using PropertyEditors.
You may also use session to store your object between GET and POST requests. Spring 3 faciliates this approach with #SessionAttributes annotation (from the Petclinic sample):
#Controller
#RequestMapping("/owners/*/pets/{petId}/edit")
#SessionAttributes("pet") // Specify attributes to be stored in the session
public class EditPetForm {
...
#InitBinder
public void setAllowedFields(WebDataBinder dataBinder) {
// Disallow binding of sensitive fields - user can't override
// values from the session
dataBinder.setDisallowedFields("id");
}
#RequestMapping(method = RequestMethod.GET)
public String setupForm(#PathVariable("petId") int petId, Model model) {
Pet pet = this.clinic.loadPet(petId);
model.addAttribute("pet", pet); // Put attribute into session
return "pets/form";
}
#RequestMapping(method = { RequestMethod.PUT, RequestMethod.POST })
public String processSubmit(#ModelAttribute("pet") Pet pet,
BindingResult result, SessionStatus status) {
new PetValidator().validate(pet, result);
if (result.hasErrors()) {
return "pets/form";
} else {
this.clinic.storePet(pet);
// Clean the session attribute after successful submit
status.setComplete();
return "redirect:/owners/" + pet.getOwner().getId();
}
}
}
However this approach may cause problems if several instances of the form are open simultaneously in the same session.
So, the most reliable approach for the complex cases is to create a separate object for storing form fields and merge changes from that object into persistent object manually.
So I ended up resolving this by annotating a method with a #ModelAttribute of the same name in the class. Spring builds the model first before executing the request mapping:
#ModelAttribute("item")
BenefitType getBenefitType(#RequestParam("id") String id) {
// return benefit type
}
While it is possible that your domain model is so simple that you can bind UI objects directly to data model objects, it is more likely that this is not so, in which case I would highly recommend you design a class specifically for form binding, then translate between it and domain objects in your controller.
I'm a little confused. I think you're actually talking about an update workflow?
You need two #RequestMappings, one for GET and one for POST:
#RequestMapping(value="/update/{id}", method=RequestMethod.GET)
public String getSave(ModelMap model, #PathVariable Long id)
{
model.putAttribute("item", benefitDao.findById(id));
return "view";
}
then on the POST actually update the field.
In you example above, your #ModelAttribute should already be populated with a method like the above method, and the properties be bound using something like JSTL or Spring tabglibs in conjunction with the form backing object.
You may also want to look at InitBinder depending on your use case.