etags in Micronaut

[prabhuveerappan]

I am trying to work on etags in Micronaut and started with small Item code using the below codes,

mn create-app --build=gradle --jdk=17 --lang=java --test=junit com.example.demo

Added class ItemController.java like below,

package com.example;

import io.micronaut.http.HttpHeaders;
import io.micronaut.http.HttpResponse;
import io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;
import io.micronaut.http.annotation.PathVariable;
import io.micronaut.http.annotation.Produces;
import jakarta.inject.Inject;

@controller("/items")
public class ItemController {

@Inject
private ItemService itemService;

@Get("/{id}")
@Produces(MediaType.APPLICATION_JSON)
public HttpResponse<Item> getItem(@PathVariable String id, HttpHeaders headers) {
    Item item = itemService.findById(id);
    if (item == null) {
        return HttpResponse.notFound();
    }

    String eTag = itemService.calculateETag(item);
    if (headers.**ifNoneMatch**().contains(eTag)) {
        return HttpResponse.notModified().**eTag**(eTag);
    } else {
        return HttpResponse.ok(item).**eTag**(eTag);
    }
}

}

Could see the highlighted ifNoneMatch and eTag are not getting recognised. Can you please help what am I missing in this simple code and why the eTag options are not getting accepted.

[graemerocher]

I assume you are coming from some other framework. These methods you are asking for are just short cuts to retrieving headers. Using headers.get(HttpHeaders.IF_MATCH) and HttpResponse.ok(item).header(HttpHeaders.ETAG, eTag) will achieve what you want.