What does the following setting in application.properties
in a Spring application do?
server.error.include-binding-errors=on-param
I can't find it in the documentation.
The always
and never
values are pretty self-explanatory, but I don't understand on-param
.
To begin, what I did is to do a global search on server.error.include-binding-errors
in the library, which lead me to spring-configuration-metadata.json
{
"name": "server.error.include-binding-errors",
"type": "org.springframework.boot.autoconfigure.web.ErrorProperties$IncludeAttribute",
"description": "When to include \"errors\" attribute.",
"sourceType": "org.springframework.boot.autoconfigure.web.ErrorProperties",
"defaultValue": "never"
},
We see the related attribute is errors
here, and the value class is IncludeAttribute
. By checking the documentation in IncludeAttribute#ON_PARAM
public static final ErrorProperties.IncludeAttribute ON_PARAM
Add error attribute when the appropriate request parameter is not "false".
We know that the errors
attribute will be added when there is a request parameter that is not "false".
If you want something concrete, let's consider the following example:
Controller
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import javax.validation.Valid;
@RestController
public class TestController {
@PostMapping("/dummy")
public String test(@Valid @RequestBody DummyDTO dummyDTO) {
return "";
}
}
DTO
import javax.validation.constraints.NotNull;
public class DummyDTO {
@NotNull(message = "mandatoryText can not be null")
private String mandatoryText;
private String canBeNullText;
public String getMandatoryText() {
return mandatoryText;
}
public void setMandatoryText(String mandatoryText) {
this.mandatoryText = mandatoryText;
}
public String getCanBeNullText() {
return canBeNullText;
}
public void setCanBeNullText(String canBeNullText) {
this.canBeNullText = canBeNullText;
}
}
Suppose we set
server.error.include-binding-errors=on-param
When we run with parameter errors=false
curl -H "Content-Type: application/json" --data '{"canBeNullText":""}' -X POST http://localhost:8080/dummy?errors=false
the result will not include errors
{
"timestamp": "2021-06-11T13:38:29.868+00:00",
"status": 400,
"error": "Bad Request",
"message": "",
"path": "/dummy"
}
When we run with parameter errors=true
curl -H "Content-Type: application/json" --data '{"canBeNullText":""}' -X POST http://localhost:8080/dummy?errors=true
the result will include errors
as
{
"timestamp": "2021-06-11T13:51:00.649+00:00",
"status": 400,
"error": "Bad Request",
"errors": [{
"codes": ["NotNull.dummyDTO.mandatoryText", "NotNull.mandatoryText", "NotNull.java.lang.String", "NotNull"],
"arguments": [{
"codes": ["dummyDTO.mandatoryText", "mandatoryText"],
"arguments": null,
"defaultMessage": "mandatoryText",
"code": "mandatoryText"
}
],
"defaultMessage": "mandatoryText can not be null",
"objectName": "dummyDTO",
"field": "mandatoryText",
"rejectedValue": null,
"bindingFailure": false,
"code": "NotNull"
}
],
"path": "/dummy"
}
References:
Implementation for web reactive
DefaultErrorWebExceptionHandler#isIncludeBindingErrors
AbstractErrorWebExceptionHandler#isBindingErrorsEnabled
Implementation for web servlet
BaseErrorController#isIncludeBindingErrors
AbstractErrorController#isBindingErrorsEnabled