Add internationalization support

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/java/com/acme/custom/CustomProblem.java

@@ -8,6 +8,7 @@
 
 import io.github.belgif.rest.problem.api.ClientProblem;
 import io.github.belgif.rest.problem.api.ProblemType;
+import io.github.belgif.rest.problem.i18n.I18N;
 
 @ProblemType(CustomProblem.TYPE)
 public class CustomProblem extends ClientProblem {
@@ -24,6 +25,7 @@ public class CustomProblem extends ClientProblem {
     @JsonCreator
     public CustomProblem(@JsonProperty("customField") String customField) {
         super(TYPE_URI, TITLE, STATUS);
+        setDetail(I18N.getLocalizedDetail(CustomProblem.class));
         this.customField = customField;
     }
 

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/java/io/github/belgif/rest/problem/AbstractRestProblemIT.java

@@ -141,6 +141,7 @@ void constraintViolationMissingRequiredQueryParameter() {
                 .get("/beanValidation/queryParameter").then().assertThat()
                 .statusCode(400)
                 .body("type", equalTo("urn:problem-type:belgif:badRequest"))
+                .body("detail", equalTo("The input message is incorrect"))
                 .body("issues[0].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
                 .body("issues[0].title", equalTo("Input value is invalid with respect to the schema"))
                 .body("issues[0].in", equalTo("query"))
@@ -338,4 +339,90 @@ void constraintViolationBodyInheritance() {
                 .body("issues[1].detail", equalTo("must not be blank"));
     }
 
+    @Test
+    void i18n() {
+        getSpec().when()
+                .header("Accept-Language", "nl-BE")
+                .queryParam("param", -1)
+                .queryParam("other", "TOO_LONG")
+                .get("/beanValidation/queryParameter").then().assertThat()
+                .statusCode(400)
+                .body("type", equalTo("urn:problem-type:belgif:badRequest"))
+                .body("detail", equalTo("Het input bericht is ongeldig"))
+                .body("issues[0].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
+                .body("issues[0].title", equalTo("Input value is invalid with respect to the schema"))
+                .body("issues[0].detail", equalTo("grootte moet tussen 0 en 5 liggen"))
+                .body("issues[0].in", equalTo("query"))
+                .body("issues[0].name", equalTo("other"))
+                .body("issues[0].value", equalTo("TOO_LONG"))
+                .body("issues[1].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
+                .body("issues[1].title", equalTo("Input value is invalid with respect to the schema"))
+                .body("issues[1].detail", equalTo("moet groter dan 0 zijn"))
+                .body("issues[1].in", equalTo("query"))
+                .body("issues[1].name", equalTo("param"))
+                .body("issues[1].value", equalTo(-1));
+    }
+
+    @Test
+    void i18nUnsupportedLanguage() {
+        getSpec().when()
+                .header("Accept-Language", "es")
+                .queryParam("param", -1)
+                .queryParam("other", "TOO_LONG")
+                .get("/beanValidation/queryParameter").then().assertThat()
+                .statusCode(400)
+                .body("detail", equalTo("The input message is incorrect"));
+    }
+
+    @Test
+    void i18nWeighted() {
+        getSpec().when()
+                .header("Accept-Language", "fr-BE;q=0.5, nl-BE;q=0.7")
+                .queryParam("param", -1)
+                .queryParam("other", "TOO_LONG")
+                .get("/beanValidation/queryParameter").then().assertThat()
+                .statusCode(400)
+                .body("type", equalTo("urn:problem-type:belgif:badRequest"))
+                .body("detail", equalTo("Het input bericht is ongeldig"))
+                .body("issues[0].detail", equalTo("grootte moet tussen 0 en 5 liggen"));
+    }
+
+    @Test
+    void i18nUnsupportedLanguageWeighted() {
+        getSpec().when()
+                .header("Accept-Language", "fr-BE;q=0.5, es;q=0.7")
+                .queryParam("param", -1)
+                .queryParam("other", "TOO_LONG")
+                .get("/beanValidation/queryParameter").then().assertThat()
+                .statusCode(400)
+                .body("detail", equalTo("The input message is incorrect"));
+    }
+
+    @Test
+    void i18nCustom() {
+        getSpec().when()
+                .header("Accept-Language", "nl-BE")
+                .get("/custom").then().assertThat()
+                .statusCode(409)
+                .body("type", equalTo("urn:problem-type:acme:custom"))
+                .body("customField", equalTo("value from frontend"))
+                .body("detail", equalTo("NL detail"));
+    }
+
+    @Test
+    void i18nDisabled() {
+        try {
+            getSpec().queryParam("enabled", "false").post("/i18n");
+            getSpec().when()
+                    .header("Accept-Language", "nl-BE")
+                    .queryParam("param", -1)
+                    .queryParam("other", "TOO_LONG")
+                    .get("/beanValidation/queryParameter").then().assertThat()
+                    .statusCode(400)
+                    .body("detail", equalTo("The input message is incorrect"));
+        } finally {
+            getSpec().queryParam("enabled", "true").post("/i18n");
+        }
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages.properties

@@ -0,0 +1 @@
+CustomProblem.detail=Custom detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_de.properties

@@ -0,0 +1 @@
+CustomProblem.detail=DE detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_fr.properties

@@ -0,0 +1 @@
+CustomProblem.detail=FR detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_nl.properties

@@ -0,0 +1 @@
+CustomProblem.detail=NL detail

belgif-rest-problem-it/belgif-rest-problem-jakarta-ee-it/src/main/java/io/github/belgif/rest/problem/FrontendImpl.java

@@ -9,6 +9,7 @@
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Positive;
 import jakarta.ws.rs.GET;
+import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.PathParam;
 import jakarta.ws.rs.QueryParam;
@@ -20,6 +21,7 @@
 import com.acme.custom.CustomProblem;
 
 import io.github.belgif.rest.problem.api.Problem;
+import io.github.belgif.rest.problem.i18n.I18N;
 import io.github.belgif.rest.problem.jaxrs.client.ProblemSupport;
 import io.github.belgif.rest.problem.model.ChildModel;
 import io.github.belgif.rest.problem.model.Model;
@@ -248,4 +250,11 @@ public Response beanValidationBodyInheritance(ChildModel body) {
         return Response.ok("body: " + body).build();
     }
 
+    @POST
+    @Path("/i18n")
+    public Response i18n(@QueryParam("enabled") boolean enabled) {
+        I18N.setEnabled(enabled);
+        return Response.ok().build();
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-java-ee-it/src/main/java/io/github/belgif/rest/problem/FrontendImpl.java

@@ -9,6 +9,7 @@
 import javax.validation.constraints.NotNull;
 import javax.validation.constraints.Positive;
 import javax.ws.rs.GET;
+import javax.ws.rs.POST;
 import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
 import javax.ws.rs.QueryParam;
@@ -20,6 +21,7 @@
 import com.acme.custom.CustomProblem;
 
 import io.github.belgif.rest.problem.api.Problem;
+import io.github.belgif.rest.problem.i18n.I18N;
 import io.github.belgif.rest.problem.jaxrs.client.ProblemSupport;
 import io.github.belgif.rest.problem.model.ChildModel;
 import io.github.belgif.rest.problem.model.Model;
@@ -246,4 +248,12 @@ public Response beanValidationBodyNested(NestedModel body) {
     public Response beanValidationBodyInheritance(ChildModel body) {
         return Response.ok("body: " + body).build();
     }
+
+    @POST
+    @Path("/i18n")
+    public Response i18n(@QueryParam("enabled") boolean enabled) {
+        I18N.setEnabled(enabled);
+        return Response.ok().build();
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-quarkus-it/src/main/java/io/github/belgif/rest/problem/quarkus/it/FrontendImpl.java

@@ -9,6 +9,7 @@
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Positive;
 import jakarta.ws.rs.GET;
+import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.PathParam;
 import jakarta.ws.rs.QueryParam;
@@ -24,6 +25,7 @@
 import io.github.belgif.rest.problem.DefaultProblem;
 import io.github.belgif.rest.problem.ServiceUnavailableProblem;
 import io.github.belgif.rest.problem.api.Problem;
+import io.github.belgif.rest.problem.i18n.I18N;
 import io.github.belgif.rest.problem.model.ChildModel;
 import io.github.belgif.rest.problem.model.Model;
 import io.github.belgif.rest.problem.model.NestedModel;
@@ -255,4 +257,11 @@ public Response beanValidationBodyInheritance(ChildModel body) {
         return Response.ok("body: " + body).build();
     }
 
+    @POST
+    @Path("/i18n")
+    public Response i18n(@QueryParam("enabled") boolean enabled) {
+        I18N.setEnabled(enabled);
+        return Response.ok().build();
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-quarkus-it/src/main/resources/application.properties

@@ -1,3 +1,4 @@
 quarkus.http.root-path=/quarkus
+quarkus.locales=en,fr-BE,nl-BE,de-BE
 quarkus.rest-client.backend.uri=http://localhost:${quarkus.http.port}/quarkus
 %test.quarkus.rest-client.backend.uri=http://localhost:${quarkus.http.test-port}/quarkus

belgif-rest-problem-it/belgif-rest-problem-spring-boot-2-it/src/main/java/io/github/belgif/rest/problem/FrontendController.java

@@ -26,6 +26,7 @@
 import com.acme.custom.CustomProblem;
 
 import io.github.belgif.rest.problem.api.Problem;
+import io.github.belgif.rest.problem.i18n.I18N;
 import io.github.belgif.rest.problem.model.ChildModel;
 import io.github.belgif.rest.problem.model.Model;
 import io.github.belgif.rest.problem.model.NestedModel;
@@ -203,4 +204,10 @@ public ResponseEntity<String> beanValidationQueryParameterNested(@Valid Model p)
         return ResponseEntity.ok("param: " + p);
     }
 
+    @PostMapping("/i18n")
+    public ResponseEntity<Void> i18n(@RequestParam("enabled") boolean enabled) {
+        I18N.setEnabled(enabled);
+        return ResponseEntity.ok().build();
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-spring-boot-3-it/src/main/java/io/github/belgif/rest/problem/FrontendController.java

@@ -27,6 +27,7 @@
 import com.acme.custom.CustomProblem;
 
 import io.github.belgif.rest.problem.api.Problem;
+import io.github.belgif.rest.problem.i18n.I18N;
 import io.github.belgif.rest.problem.model.ChildModel;
 import io.github.belgif.rest.problem.model.Model;
 import io.github.belgif.rest.problem.model.NestedModel;
@@ -223,4 +224,10 @@ public ResponseEntity<String> beanValidationQueryParameterNested(@Valid Model p)
         return ResponseEntity.ok("param: " + p);
     }
 
+    @PostMapping("/i18n")
+    public ResponseEntity<Void> i18n(@RequestParam("enabled") boolean enabled) {
+        I18N.setEnabled(enabled);
+        return ResponseEntity.ok().build();
+    }
+
 }

belgif-rest-problem-java-ee/pom.xml

@@ -57,6 +57,11 @@
       <artifactId>mockito-junit-jupiter</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.junit-pioneer</groupId>
+      <artifactId>junit-pioneer</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.hibernate.validator</groupId>
       <artifactId>hibernate-validator</artifactId>
@@ -79,6 +84,17 @@
 
   <build>
     <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <configuration>
+          <!-- https://junit-pioneer.org/docs/environment-variables/#warnings-for-reflective-access -->
+          <argLine>
+            --add-opens java.base/java.util=ALL-UNNAMED
+            --add-opens java.base/java.lang=ALL-UNNAMED
+          </argLine>
+        </configuration>
+      </plugin>
       <plugin>
         <groupId>org.eclipse.transformer</groupId>
         <artifactId>transformer-maven-plugin</artifactId>

belgif-rest-problem-java-ee/src/main/java/io/github/belgif/rest/problem/jaxrs/i18n/I18NAcceptLanguageFilter.java

@@ -0,0 +1,34 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import javax.ws.rs.container.ContainerRequestContext;
+import javax.ws.rs.container.ContainerRequestFilter;
+import javax.ws.rs.container.ContainerResponseContext;
+import javax.ws.rs.container.ContainerResponseFilter;
+import javax.ws.rs.container.PreMatching;
+import javax.ws.rs.ext.Provider;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+/**
+ * Filter that registers the requested locale, as specified in Accept-Language HTTP header,
+ * with the {@link ThreadLocalLocaleResolver} (and clears it afterward).
+ */
+@PreMatching
+@Provider
+public class I18NAcceptLanguageFilter implements ContainerRequestFilter, ContainerResponseFilter {
+
+    @Override
+    public void filter(ContainerRequestContext requestContext) {
+        if (I18N.isEnabled() && !requestContext.getAcceptableLanguages().isEmpty()) {
+            ThreadLocalLocaleResolver.setLocale(requestContext.getAcceptableLanguages().get(0));
+        }
+    }
+
+    @Override
+    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
+        if (I18N.isEnabled()) {
+            ThreadLocalLocaleResolver.clear();
+        }
+    }
+
+}

belgif-rest-problem-java-ee/src/main/java/io/github/belgif/rest/problem/jaxrs/i18n/I18NConfigurator.java

@@ -0,0 +1,34 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import static io.github.belgif.rest.problem.i18n.I18N.*;
+
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+import javax.servlet.annotation.WebListener;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+/**
+ * ServletContextListener that enables/disables I18N based on the "io.github.belgif.rest.problem.i18n"
+ * parameter, which is resolved from following configuration locations in order:
+ * <ol>
+ * <li>System property</li>
+ * <li>Environment variable</li>
+ * <li>web.xml context param</li>
+ * </ol>
+ */
+@WebListener
+public class I18NConfigurator implements ServletContextListener {
+
+    @Override
+    public void contextInitialized(ServletContextEvent sce) {
+        if (System.getProperty(I18N_FLAG) != null) {
+            I18N.setEnabled(Boolean.parseBoolean(System.getProperty(I18N_FLAG)));
+        } else if (System.getenv(I18N_FLAG) != null) {
+            I18N.setEnabled(Boolean.parseBoolean(System.getenv(I18N_FLAG)));
+        } else if (sce.getServletContext().getInitParameter(I18N_FLAG) != null) {
+            I18N.setEnabled(Boolean.parseBoolean(sce.getServletContext().getInitParameter(I18N_FLAG)));
+        }
+    }
+
+}