Add Custom Exception Handler

backend/src/main/java/uk/ac/ebi/spot/ols/controller/api/exception/BadRequestException.java

@@ -0,0 +1,7 @@
+package uk.ac.ebi.spot.ols.controller.api.exception;
+
+public class BadRequestException extends RuntimeException {
+    public BadRequestException(String message) {
+        super(message);
+    }
+}

backend/src/main/java/uk/ac/ebi/spot/ols/controller/api/exception/CustomErrorController.java

@@ -0,0 +1,38 @@
+package uk.ac.ebi.spot.ols.controller.api.exception;
+
+import org.springframework.boot.web.servlet.error.ErrorController;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import javax.servlet.http.HttpServletRequest;
+
+@RestController
+public class CustomErrorController implements ErrorController {
+
+    @RequestMapping(value = "/error", produces = MediaType.APPLICATION_JSON_VALUE)
+    @ResponseBody
+    public ResponseEntity<ErrorResponse> handleError(HttpServletRequest request) {
+        Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
+        Exception exception = (Exception) request.getAttribute("javax.servlet.error.exception");
+
+        if (statusCode == null) {
+            statusCode = HttpStatus.INTERNAL_SERVER_ERROR.value();
+        }
+
+        String errorMessage = "An unexpected error occurred";
+        if (exception != null) {
+            errorMessage = exception.getMessage();
+        } else if (statusCode == HttpStatus.NOT_FOUND.value()) {
+            errorMessage = "The requested resource was not found";
+        }
+
+        ErrorResponse errorResponse = new ErrorResponse(statusCode, errorMessage);
+        return ResponseEntity.status(statusCode)
+                .contentType(MediaType.APPLICATION_JSON)
+                .body(errorResponse);
+    }
+}

backend/src/main/java/uk/ac/ebi/spot/ols/controller/api/exception/ErrorResponse.java

@@ -0,0 +1,16 @@
+package uk.ac.ebi.spot.ols.controller.api.exception;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class ErrorResponse {
+    @JsonProperty("status")
+    private int http_status;
+
+    @JsonProperty("message")
+    private String message;
+
+    public ErrorResponse(int http_status, String message) {
+        this.http_status = http_status;
+        this.message = message;
+    }
+}

backend/src/main/java/uk/ac/ebi/spot/ols/controller/api/exception/GlobalExceptionHandler.java

@@ -0,0 +1,41 @@
+package uk.ac.ebi.spot.ols.controller.api.exception;
+
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.servlet.NoHandlerFoundException;
+
+@ControllerAdvice
+@Order(Ordered.HIGHEST_PRECEDENCE)
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(NoHandlerFoundException.class)
+    @ResponseBody
+    public ResponseEntity<ErrorResponse> handleNoHandlerFoundException(NoHandlerFoundException ex) {
+        ErrorResponse error = new ErrorResponse(HttpStatus.NOT_FOUND.value(), "Endpoint not found: " + ex.getRequestURL());
+        return ResponseEntity.status(HttpStatus.NOT_FOUND)
+                .contentType(MediaType.APPLICATION_JSON)
+                .body(error);
+    }
+
+    @ExceptionHandler(Exception.class)
+    @ResponseBody
+    public ResponseEntity<ErrorResponse> handleAllExceptions(Exception ex) {
+        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
+        if (ex instanceof ResourceNotFoundException) {
+            status = HttpStatus.NOT_FOUND;
+        } else if (ex instanceof BadRequestException) {
+            status = HttpStatus.BAD_REQUEST;
+        }
+
+        ErrorResponse error = new ErrorResponse(status.value(), ex.getMessage());
+        return ResponseEntity.status(status)
+                .contentType(MediaType.APPLICATION_JSON)
+                .body(error);
+    }
+}

backend/src/main/java/uk/ac/ebi/spot/ols/controller/api/exception/ResourceNotFoundException.java

@@ -0,0 +1,7 @@
+package uk.ac.ebi.spot.ols.controller.api.exception;
+
+public class ResourceNotFoundException extends RuntimeException {
+    public ResourceNotFoundException(String message) {
+        super(message);
+    }
+}

backend/src/main/resources/application.properties

@@ -2,4 +2,9 @@ spring.jackson.serialization.INDENT_OUTPUT=true
 
 springdoc.swagger-ui.path=/swagger-ui-ols4.html
 springdoc.swagger-ui.operationsSorter=method
-springdoc.swagger-ui.disable-swagger-default-url=true
+springdoc.swagger-ui.disable-swagger-default-url=true
+
+spring.mvc.throw-exception-if-no-handler-found=true
+spring.web.resources.add-mappings=false
+
+server.error.whitelabel.enabled=false