I am new in struts2 . I have created an XML file for validations, but when I test my form I don't get the error messages that I configured in the XML file. instead I get the Struts 2 defaults messages such as this one :
invalid field value for field "capteur.ENERGIE_CAPTEUR".
Is there anyway to make struts2 prints the messages configured in the XML file instead of the default ones ?
That is not a validation error message, it is a conversion error message.
You can override the default conversion error message up to each single object, by creating an entry for it in the global .properties file, as described in Struts 2 documentation, Type Conversion Errors Handling:
By default, all conversion errors are reported using the generic i18n
key xwork.default.invalid.fieldvalue, which you can override (the
default text is Invalid field value for field "xxx", where xxx is the
field name) in your global i18n resource bundle.
However, sometimes you may wish to override this message on a
per-field basis. You can do this by adding an i18n key associated with
just your action (Action.properties) using the pattern
invalid.fieldvalue.xxx, where xxx is the field name.
If you are interested in understanding how it works in a deeper way, read the Short Story about Validation, Conversion and Friends.
Related
I am having a case in which I would like to do some input validation on the #RequestParams of an endpoint.
I know about Validators and Custom Validators, and my current strategy implies creating a wrapper object around the RequestParams, a custom validator and apply class level the annotation that triggers the custom validation.
My problem is that the custom validation is implementing ConstraintValidator, which means that the validator will either return true or false, and an error will be created by Spring with some text (I also know that I can change this text). My desire, however, is to create a custom payload back to the client. An example could be
class MyError {
int code;
String message;
}
The way to return this object is through a #ControllerAdvice Error handler, which understands that a ConstraintValidationException should return my custom payload format. However, I need to return different codes and messages for different reasons on the input validation failed. For example:
A Field is empty -> code XXX
A Field is formatted incorrectly -> code YYY
As far as I know, there is little customization possible on the exception that is reachable from my #ControllerAdvice, I can get a list of errors that happened but I cannot easily determine what happened. (Technically I can, but it would have to be based on the message string, which is pretty weak).
Is there a way to provide extra data to the Exception so I can distinguish from the #ControllerAdvice what happened and create my custom error response accordingly?
Am I approaching it the wrong way?
You can intercept the BindException (https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/validation/BindException.html) with the #ExceptionHandler. This contains detailed information about all validation errors. For example, with e.getFieldErrors() you can access all errors associated with fields.
For example, for a field
#MyConstraint
#Length(min = 3)
private String field;
that failed validation you get the following information in the exception:
Field error in object data on field field: rejected value [XY]; codes [Length.data.field,Length.field,Length.java.lang.String,Length].
Field error in object data on field field: rejected value [XY]; codes [MyConstraint.data.field,MyConstraint.field,MyConstraint.java.lang.String,MyConstraint].
From this you can see that it failed the #Length constraint and the custom #MyConstraint constraint.
I have an array of possible i18n message codes. Lets call it codes. Let's assume it contains values
[most.specific, specific, default]
Let's assume the messages.properties contains messages for specific and default, but not for most.specific.
I would be happy to be able to write in my Thymeleaf template something like
#{${codes}}
to get a message for specific code (since it is the first one that is defined).
I need Thymeleaf to resolve the first available message code that is defined in messages file into a string, ignoring the other message codes.
How to do this concisely?
My config file with my validation rules works fine when calling the form_validation->run('form'). The thing is that I want to set custom error message for one of the fields. So in the controller I just add: ..set_message('field','message'). But it's not registering, I get the default error message: .... is required.
For changing the message for the existing validation rules, just do the following.
Copy the form_validation_lang.php file from system/language/english to application/language/english
Modify the message for your validation rule name.
For example for changing message for required field change the below line.
$lang['required'] = "The %s field is required.";
I am in reference to the following method from BindingResult:
BindingResult.html#resolveMessageCodes(java.lang.String, java.lang.String)
I am trying to figure out the difference between an error code and a message code. Can someone please provide an example, especially one that would illustrate why there could be several message codes for a given error code?
Because web applications are internationalized, when you reject an object and want to have a message displayed for it, you don't use a hardcoded text because that will show the same no matter the language.
Instead, you specify an error code that later server as a key to retrieving the proper message from the bundles (and now the error code is a message code from the point of view of the method that must find the proper message text).
Your error code resolves to more message codes because Spring (based on the implementation) adds some additional ones for you. Here is a snippet from the Spring documentation:
[...] What error codes it registers is determined by the MessageCodesResolver that is used. By default, the DefaultMessageCodesResolver is used, which for example not only registers a message with the code you gave, but also messages that include the field name you passed to the reject method. So in case you reject a field using rejectValue("age", "too.darn.old"), apart from the too.darn.old code, Spring will also register too.darn.old.age and too.darn.old.age.int (so the first will include the field name and the second will include the type of the field); this is done as a convenience to aid developers in targeting error messages and suchlike. [...]
The last statement is the reason there are more message codes, to have control on the message that is displayed to the user, from a generic one (e.g. "Value required") to a more specific one given the context (e.g. "A value is required for field XXX").
The javadoc for DefaultMessageCodesResolver explains it further and gives an example:
For example, in case of code "typeMismatch", object name "user", field "age":
try "typeMismatch.user.age"
try "typeMismatch.age"
try "typeMismatch.int"
try "typeMismatch"
This resolution algorithm thus can be leveraged for example to show specific messages for binding errors like "required" and "typeMismatch":
at the object + field level ("age" field, but only on "user");
at the field level (all "age" fields, no matter which object name);
or at the general level (all fields, on any object).
I have a field "length" in one of my struts 2 form. The data-type of "length" is "double". I have applied the "double" validation in XML file. But when I key-in alphabets in the "length" text field, it shows the error message as
Invalid field value for field "length"
I don't want this message to be shown like this. This message is generated by struts 2 itself and not entered by me. I guess, this message comes as the conversion of data fails. I also applied the "conversion" validator, but the above error message is still showing up. Please suggest the solution.
Thanks in advance.
You're in luck. This text is customizable.
The text is defined in xwork-messages.properties in the xwork jar. You can override it by adding the following to your global i18n resource bundle:
xwork.default.invalid.fieldvalue=Invalid field value for field "{0}".
As you guessed, this error message occurs for all type conversion failures. The XWorkConverter class has some useful javadoc about this:
Any error that occurs during type conversion may or may not wish to be reported. For example, reporting that the input "abc" could not be converted to a number might be important. On the other hand, reporting that an empty string, "", cannot be converted to a number might not be important - especially in a web environment where it is hard to distinguish between a user not entering a value vs. entering a blank value.
By default, all conversion errors are reported using the generic i18n key xwork.default.invalid.fieldvalue, which you can override (the default text is Invalid field value for field "xxx", where xxx is the field name) in your global i18n resource bundle.
However, sometimes you may wish to override this message on a per-field basis. You can do this by adding an i18n key associated with just your action (Action.properties) using the pattern invalid.fieldvalue.xxx, where xxx is the field name.
It is important to know that none of these errors are actually reported directly. Rather, they are added to a map called conversionErrors in the ActionContext. There are several ways this map can then be accessed and the errors can be reported accordingly.
try this,
<field name="percentage">
<field-validator type="double">
<param name="minExclusiveExpression">${minExclusiveValue}</param>
<param name="maxExclusiveExpression">${maxExclusiveValue}</param>
<message>Percentage needs to be between ${minExclusive} and ${maxExclusive} (exclusive)</message>
</field-validator>
</field>