Errors now returned in JSON-LD.

src/controller/ComponentController.ts

@@ -7,6 +7,7 @@ import { NodeObject } from "jsonld";
 import BaseController from "./BaseController";
 import TypeDefinition from "../entity/TypeDefinition";
 import ComponentInformation from "../entity/ComponentInformation";
+import APIError from "./util/APIError";
 
 const logger = logService(module);
 
@@ -33,7 +34,8 @@ export default class ComponentController extends BaseController {
             // It won't have valid context information anyway and is only intended
             // for internal use.
             response.status(404);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError("Component not found."));
             return;
         }
 
@@ -44,12 +46,13 @@ export default class ComponentController extends BaseController {
                 response.send(componentJsonLd);
             } else {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Component not found."));
             }
         }).catch((error) => {
             logger.error(`Error while retrieving component: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            response.send(new APIError(JSON.stringify(error)));
         });
     }
 
@@ -74,7 +77,8 @@ export default class ComponentController extends BaseController {
         Component.find(filter, fromDate, toDate, pageSize, page, this.componentRepository).then((components) => {
             if(components.length == 0) {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("No component found for this query."));
                 return;
             }
 
@@ -83,7 +87,8 @@ export default class ComponentController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while searching for components: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(JSON.stringify(error)));
         });
     }
 
@@ -95,7 +100,8 @@ export default class ComponentController extends BaseController {
             response.send(result);
         } else {
             response.status(404);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError("No roots found."));
         }
     }
 
@@ -115,7 +121,8 @@ export default class ComponentController extends BaseController {
             if(!parentComponent) {
                 logger.error("Cannot find component with id: ", request.params.parentComponentId);
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError(`Component with id ${parentComponentId} does not exist.`));
                 return;
             }
 
@@ -123,7 +130,8 @@ export default class ComponentController extends BaseController {
 
             if(!type) {
                 response.status(404);
-                response.send({ message: "Type definition not found." });
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Type definition not found."));
                 return;
             }
 
@@ -132,7 +140,8 @@ export default class ComponentController extends BaseController {
             if(currentinformationWithTopic.length > 0) {
                 // The topic is already in use by other information.
                 response.status(412);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Topic currently in use by another ComponentInformation."));
                 return;
             }
 
@@ -152,7 +161,8 @@ export default class ComponentController extends BaseController {
                 } catch(error) {
                     logger.error(`Error while searching for measurement targets: ${JSON.stringify(error)}`);
                     response.status(404);
-                    response.send();
+                    this.setJSONLDResponseType(response);
+                    response.send(new APIError(`Error while searching for target: ${JSON.stringify(error)}`));
                     return;
                 }
             }
@@ -165,7 +175,8 @@ export default class ComponentController extends BaseController {
                 // Verification of information schema failed.
                 logger.error(`information verification failed: ${error}`);
                 response.status(400);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError(`Component Information verification failed: ${error}`));
                 return;
             }
 
@@ -177,12 +188,7 @@ export default class ComponentController extends BaseController {
                 } else {
                     response.status(400);
                     this.setJSONLDResponseType(response);
-                    response.send({
-                        "@context": {
-                            "message": "https://schema.org/error"
-                        }, 
-                        "message": "License URL for parent relation not set."
-                    });
+                    response.send(new APIError("License URL for parent relation not set."));
                     return;
                 }
             } else {
@@ -200,7 +206,8 @@ export default class ComponentController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while retrieving parent component: ${error}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while retrieving parent component: ${JSON.stringify(error)}`));
         });
     }
 

src/controller/ComponentInformationController.ts

@@ -5,6 +5,7 @@ import logService from "../services/logger";
 import BaseController from "./BaseController";
 import TypeDefinition from "../entity/TypeDefinition";
 import Component from "../entity/Component";
+import APIError from "./util/APIError";
 
 const logger = logService(module);
 
@@ -34,7 +35,8 @@ export default class ComponentInformationController extends BaseController {
         }).catch((error) => {
             logger.error(`Cannot find information by Id: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Cannot find information by Id: ${JSON.stringify(error)}`));
         });
     }
 
@@ -60,7 +62,8 @@ export default class ComponentInformationController extends BaseController {
         ComponentInformation.find(filter, fromDate, toDate, metadataTypeFilter, pageSize, page, this.componentInformationRepository).then(async (informationArray) => {
             if(informationArray.length == 0) {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("No result found for this query."));
                 return;
             }
 
@@ -69,7 +72,8 @@ export default class ComponentInformationController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while searching component information: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while searching component information: ${JSON.stringify(error)}`));
         });
     }
 
@@ -78,9 +82,10 @@ export default class ComponentInformationController extends BaseController {
 
         this.componentInformationRepository.findOne(oldVersionId, { relations: ["component", "nextVersion"] }).then(async (oldVersionInformation) => {
             if (!oldVersionInformation) {
-                logger.error("Cannot find information with id: ", request.params.oldVersionId);
+                logger.error(`Cannot find information with id: ${request.params.oldVersionId}`);
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError(`Cannot find information with id: ${request.params.oldVersionId}`));
                 return;
             }
 
@@ -89,7 +94,8 @@ export default class ComponentInformationController extends BaseController {
             if (oldVersionInformation.nextVersion != null) {
                 // 412: Precondition failed
                 response.status(412);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Information already has a new version set."));
                 return;
             }
 
@@ -110,7 +116,8 @@ export default class ComponentInformationController extends BaseController {
                     // Topic is already related by a information object which is not
                     // the old version.
                     response.status(412);
-                    response.send();
+                    this.setJSONLDResponseType(response);
+                    response.send(new APIError("Topic is already in use by another component information."));
                     return;
                 }
             }
@@ -119,14 +126,16 @@ export default class ComponentInformationController extends BaseController {
 
             if(!type) {
                 response.status(404);
-                response.send({ message: "Type definition not found." });
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Type definition not found."));
                 return;
             }
 
             if (!type.validateData(metadata)) {
                 // Verification of information schema failed.
                 response.status(400);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Verification of information schema failed."));
                 return;
             }
 
@@ -146,7 +155,8 @@ export default class ComponentInformationController extends BaseController {
                 } catch(error) {
                     logger.error(`Error while searching for measurement targets: ${JSON.stringify(error)}`);
                     response.status(404);
-                    response.send();
+                    this.setJSONLDResponseType(response);
+                    response.send(new APIError(`Error while searching for measurement targets: ${JSON.stringify(error)}`));
                     return;
                 }
             }
@@ -160,7 +170,8 @@ export default class ComponentInformationController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while retrieving old version: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while retrieving old version: ${JSON.stringify(error)}`));
         });
     }
 

src/controller/ComponentRelationController.ts

@@ -4,6 +4,7 @@ import ComponentRelation from "../entity/ComponentRelation";
 import Component from "../entity/Component";
 import BaseController from "./BaseController";
 import logService from "../services/logger";
+import APIError from "./util/APIError";
 
 const logger = logService(module);
 
@@ -27,12 +28,14 @@ export default class ComponentRelationController extends BaseController {
                 response.send(relation.toJSONLD());
             } else {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Relation not found."));
             }
         }).catch((error) => {
             logger.error(`Cannot find relation by Id: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Cannot find relation by Id: ${JSON.stringify(error)}`));
         });
     }
 
@@ -44,7 +47,8 @@ export default class ComponentRelationController extends BaseController {
         ComponentRelation.find(filter, pageSize, page, this.componentRelationRepository).then((relations) => {
             if(relations.length == 0) {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("No relation found."));
                 return;
             }
 
@@ -53,7 +57,8 @@ export default class ComponentRelationController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while searching component relation: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while searching component relation: ${JSON.stringify(error)}`));
         });
     }
 
@@ -64,7 +69,8 @@ export default class ComponentRelationController extends BaseController {
         if(!component) {
             logger.error(`Cannot find component with id: ${JSON.stringify(request.body.componentId)}`);
             response.status(404);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Cannot find component with id: ${JSON.stringify(request.body.componentId)}`));
             return;
         }
 
@@ -73,35 +79,41 @@ export default class ComponentRelationController extends BaseController {
         if(!newParentComponent) {
             logger.error(`Cannot find parent component with id: ${request.body.newParentComponentId}`);
             response.status(404);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Cannot find parent component with id: ${request.body.newParentComponentId}`));
             return;
         }
 
         if(component == null) {
             response.status(404);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError("Component not found."));
             return;
         }
 
         // Ensure that the user does not try to move the root itself.
         if(Component.rootId == component.id) {
             response.status(400);
-            response.send();
+            this.setJSONLDResponseType(response);
+            // Pretend that this internal root does not exist.
+            response.send(new APIError("Component not found."));
             return;
         }
 
         if(newParentComponent.id == component.id) {
             // A component cannot be a parent of itself.
             response.status(400);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError("A component cannot be a parent of itself."));
             return;
         }
 
         const oldRelation: ComponentRelation | undefined = await ComponentRelation.findParentRelation(component, this.componentRelationRepository);
 
         if(component == null) {
+            this.setJSONLDResponseType(response);
             response.status(404);
-            response.send();
+            response.send(new APIError("Component not found."));
             return;
         }
 
@@ -137,8 +149,9 @@ export default class ComponentRelationController extends BaseController {
         } catch (error) {
             logger.error(`Error while creating a relation: ${JSON.stringify(error)}`);
             await queryRunner.rollbackTransaction();
+            this.setJSONLDResponseType(response);
             response.status(500);
-            response.send(error);
+            response.send(new APIError(`Error while creating a relation: ${JSON.stringify(error)}`));
         } finally {
             await queryRunner.release();
         }

src/controller/MeasurementController.ts

@@ -3,6 +3,7 @@ import { Repository, Connection } from "typeorm";
 import Measurement from "../entity/Measurement";
 import logService from "../services/logger";
 import BaseController from "./BaseController";
+import APIError from "./util/APIError";
 
 const logger = logService(module);
 
@@ -24,13 +25,15 @@ export default class MeasurementController extends BaseController {
                 this.setJSONLDResponseType(response);
                 response.send(measurementJsonLd);
             } else {
+                this.setJSONLDResponseType(response);
                 response.status(404);
-                response.send();
+                response.send(new APIError("Measurement not found."));
             }
         }).catch((error) => {
             logger.error(`Error while retrieving measurement: ${JSON.stringify(error)}`);
             response.status(500);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(`Error while retrieving measurement: ${JSON.stringify(error)}`);
         });
     }
 
@@ -58,17 +61,18 @@ export default class MeasurementController extends BaseController {
         Measurement.find(filter, fromDate, toDate, valueTypeFilter, metadataTypeFilter, informationTypeFilter, pageSize, page, this.measurementRepository).then((results) => {
             if(results.length == 0) {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("No measurement found."));
                 return;
             }
 
             this.setJSONLDResponseType(response);
             response.send(results.map(measurement => measurement.toJSONLD()));
         }).catch((error) => {
-            // TODO
             logger.error(`Error while querying measurements: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while querying measurements: ${JSON.stringify(error)}`));
         });
     };
 

src/controller/TypeDefinitionController.ts

@@ -3,6 +3,7 @@ import TypeDefinition from "../entity/TypeDefinition";
 import logService from "../services/logger";
 import BaseController from "./BaseController";
 import { Connection, Repository } from "typeorm";
+import APIError from "./util/APIError";
 
 const logger = logService(module);
 
@@ -21,12 +22,14 @@ export default class TypeDefinitionController extends BaseController {
                 response.send(type);
             } else {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("Type Definition not found."));
             }
         }).catch((error) => {
             logger.error(`Error while searching for type ${request.body.name}: ${error}`);
             response.status(500);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while searching for type ${request.body.name}: ${error}`));
         });
     }
 
@@ -39,7 +42,8 @@ export default class TypeDefinitionController extends BaseController {
         TypeDefinition.search(name ?? "", pageSize, page, this.repository).then((results) => {
             if(results.length == 0) {
                 response.status(404);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("No Type Definition found."));
                 return;
             }
 
@@ -47,7 +51,8 @@ export default class TypeDefinitionController extends BaseController {
         }).catch((error) => {
             logger.error(`Error while searching type definitions: ${JSON.stringify(error)}`);
             response.status(400);
-            response.send(error);
+            this.setJSONLDResponseType(response);
+            response.send(`Error while searching type definitions: ${JSON.stringify(error)}`);
         });
     }
 
@@ -59,9 +64,8 @@ export default class TypeDefinitionController extends BaseController {
             TypeDefinition.validateSchema(schema);
         } catch(error) {
             response.status(400);
-            response.send({
-                message: (error as Error).toString()
-            });
+            this.setJSONLDResponseType(response);
+            response.send(new APIError((error as Error).toString()));
             return;
         }
 
@@ -83,12 +87,14 @@ export default class TypeDefinitionController extends BaseController {
             if(error.code == "23505") {
                 // 412 - Precondition Failed
                 response.status(412);
-                response.send();
+                this.setJSONLDResponseType(response);
+                response.send(new APIError("A type definition with this name already exists."));
                 return;
             }
 
             response.status(500);
-            response.send();
+            this.setJSONLDResponseType(response);
+            response.send(new APIError(`Error while saving new type definition: ${JSON.stringify(error)}`));
         });
     }
 

src/controller/util/APIError.ts

+
+export default class APIError {
+
+    message: string;
+
+    constructor(message: string) {
+        this.message = message;
+    }
+
+    toJSON(): unknown {
+        return {
+            "@context": {
+                "message": "https://schema.org/error"
+            },
+            "message": this.message
+        };
+    }
+
+}
\ No newline at end of file

src/middleware/ValidationErrorMiddleware.ts

 import { Request, Response, NextFunction } from "express";
 import { validationResult } from "express-validator";
+import APIError from "../controller/util/APIError";
 
 export default (request: Request, response: Response, next: NextFunction): void => {
     const result = validationResult(request);
@@ -12,12 +13,7 @@ export default (request: Request, response: Response, next: NextFunction): void
     response.type("application/ld+json");
     response.send(
         result.array().map((error) => {
-            return {
-                "@context": {
-                    "message": "https://schema.org/error"
-                }, 
-                "message": error.msg
-            };
+            return new APIError(error.msg);
         }) 
     );
     return;