Fix API returning HTML error pages when user sends invalid JSON

src/main/java/edu/harvard/iq/dataverse/api/errorhandlers/JsonExceptionsHandler.java

@@ -0,0 +1,52 @@
+package edu.harvard.iq.dataverse.api.errorhandlers;
+
+import edu.harvard.iq.dataverse.api.util.JsonResponseBuilder;
+import edu.harvard.iq.dataverse.util.json.JsonParseException;
+import jakarta.json.stream.JsonParsingException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.ws.rs.core.Context;
+import jakarta.ws.rs.core.Response;
+import jakarta.ws.rs.ext.ExceptionMapper;
+import jakarta.ws.rs.ext.Provider;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Make a failing JSON parsing request appear to be a BadRequest (error code 400)
+ * and send a message what just failed...
+ */
+public abstract class JsonExceptionsHandler<T extends Exception> implements ExceptionMapper<T>{
+
+    static final Logger logger = Logger.getLogger(JsonExceptionsHandler.class.getSimpleName());
+
+    @Context
+    HttpServletRequest request;
+
+    @Override
+    public Response toResponse(T ex) {
+        return JsonResponseBuilder.error(Response.Status.BAD_REQUEST)
+            .log(logger, Level.FINER)
+            .message(ex.getMessage())
+            .build();
+    }
+
+    /**
+     * Handler for jakarta.json.stream.JsonParsingException
+     */
+    @Provider
+    public static class JsonParsingExceptionMapper extends JsonExceptionsHandler<JsonParsingException> {
+    }
+
+    /**
+     * Handler for jakarta.json.stream.JsonParsingException
+     */
+    @Provider
+    public static class DvUtilJsonParseExceptionMapper extends JsonExceptionsHandler<JsonParseException> {
+    }
+
+    // Add more handlers as needed (e.g., for Jackson, GSON, etc.)
+    // @Provider
+    // public static class JsonProcessingExceptionMapper extends JsonExceptionHandler<JsonProcessingException> {
+    // }
+}

src/main/java/edu/harvard/iq/dataverse/api/util/JsonResponseBuilder.java

@@ -1,6 +1,7 @@
 package edu.harvard.iq.dataverse.api.util;
 
 import jakarta.json.Json;
+import jakarta.json.JsonObject;
 import jakarta.json.JsonValue;
 import jakarta.json.JsonObjectBuilder;
 import jakarta.servlet.ServletResponse;
@@ -143,8 +144,9 @@ public JsonResponseBuilder internalError(Throwable ex) {
      * @return JAX-RS response including JSON message
      */
     public Response build() {
+        JsonObject entity = entityBuilder.build();
         return jerseyResponseBuilder.type(MediaType.APPLICATION_JSON_TYPE)
-            .entity(this.entityBuilder.build())
+            .entity(entity)
             .build();
     }
 
@@ -215,9 +217,14 @@ public JsonResponseBuilder log(Logger logger, Level level, Optional<Throwable> e
         if ( ! logger.isLoggable(level) || alreadyLogged )
             return this;
 
-        StringBuilder metadata = new StringBuilder("");
-        this.entityBuilder.build()
-            .forEach((k,v) -> metadata.append("_"+k+"="+v.toString()+";"));
+        // This is necessary because we need to build in two places: logging and response creation.
+        // Without cloning the object builder, we'd end up with an empty entity in the response when logging before that.
+        JsonObject entity = this.entityBuilder.build();
+        this.entityBuilder = Json.createObjectBuilder(entity);
+
+        StringBuilder metadata = new StringBuilder();
+        entity.forEach((k,v) -> metadata.append("_").append(k).append("=").append(v.toString()).append(";"));
+
         // remove trailing ;
         metadata.deleteCharAt(metadata.length()-1);
 

src/test/java/edu/harvard/iq/dataverse/api/AdminIT.java

@@ -19,7 +19,6 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
-
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
@@ -29,7 +28,6 @@
 import java.util.Map;
 import java.util.UUID;
 import java.util.logging.Logger;
-
 import static io.restassured.RestAssured.given;
 import static jakarta.ws.rs.core.Response.Status.BAD_REQUEST;
 import static jakarta.ws.rs.core.Response.Status.CREATED;
@@ -43,6 +41,7 @@
 import static org.hamcrest.CoreMatchers.notNullValue;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import io.restassured.http.ContentType;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class AdminIT {
@@ -681,6 +680,19 @@ public void testCreateNonBuiltinUserViaApi() {
         assertEquals(200, deleteUserToConvert.getStatusCode());
     }
 
+
+    @Test
+    void testCreateUserViaAPI_WithInvalidJson() {
+        Response response = given()
+            .body("{invalid}")
+            .contentType(ContentType.JSON)
+            .post("/api/admin/authenticatedUsers");
+
+        response.then()
+            .assertThat()
+            .statusCode(BAD_REQUEST.getStatusCode())
+            .body("message", containsString("Unexpected char"));
+    }
 
 
     @Test