CODEWITHSUNDEEP
javaspringspring-bootresthttp
Konrad Adamek
Konrad Adamek

Reputation: 176

How to create interceptor for transforming http headers to custom dto?

In one of my app I have many endpoints with the same set of headers:

@RequestHeader("foo") String foo,
@RequestHeader("bar") String bar,
@RequestHeader("baz") String baz,

and in each controller method I am creating my custom dto based on those headers:

MyDto myDto = new MyDto(foo, bar, baz);

To avoid duplicates and adding/removing one header 50 times to each method, I want to have something like interceptor class that will take HttpHeaders and will transform it MyDto only once, so then I want to be able to replace all request headers in controller methods by simply MyDto myDto created behind the scenes.

I tried to find solution, but didn't found anything.

Actual:

@PostMapping("/myEndpoint")
public MyResponse myEndpoint(@RequestHeader("foo") String foo,
                             @RequestHeader("bar") String bar,
                             @RequestHeader("baz") String baz,
                             @RequestBody MyRequest myRequest) {

    MyDto myDto = new MyDto(foo, bar, baz);
    myService.doSomething(myDto);

    ...
}

Expected:

@PostMapping("/myEndpoint")
public MyResponse myEndpoint(MyDto myDto,
                             @RequestBody MyRequest myRequest) {

    myService.doSomething(myDto);

    ...
}

I also have a method for it:

public MyDto transform(HttpHeaders httpHeaders) {

    String foo = getHeader(httpHeaders, "foo");
    String bar = getHeader(httpHeaders, "bar");
    String baz = getHeader(httpHeaders, "baz");

    return new MyDto(foo, bar, baz);
}

private String getHeader(HttpHeaders httpHeaders,
                         String key) {

    return Optional.ofNullable(httpHeaders.get(key))
                   .map(Collection::stream)
                   .orElseGet(Stream::empty)
                   .findFirst()
                   .orElse(null);
}

But I don't know when I can call it to make it runnable on each request.

Upvotes: 1

Views: 607

Answers (1)

Marco Behler
Marco Behler

Reputation: 3724

I was about to say , write and register a custom HandlerInterceptor. It would allow you to access the headers, but the problem is you won't get access to the converted @RequestBody object - at least, as far as I know. I don't think this can easily be done.

Upvotes: 1

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