Issue #203 : implemented user friendly error messages. (#100)

* Issue #203 : implemented user friendly error messages.

Author: suratdas

src/http-exception.filter.ts

@@ -9,20 +9,35 @@ export class HttpExceptionFilter implements ExceptionFilter {
     const request = ctx.getRequest<Request>();
 
     let status: number;
+    const isUniqueConstaintException = this.isUniqueConstraintException(exception);
     try {
-      status = exception.getStatus();
+      status = isUniqueConstaintException ? HttpStatus.BAD_REQUEST : exception.getStatus();
     } catch {
       status = HttpStatus.INTERNAL_SERVER_ERROR;
     }
+    const message = isUniqueConstaintException ? this.getCustomMessageForException(exception) : exception.message;
 
     Logger.error(exception, exception.stack);
 
     response.status(status).json({
       path: request.url,
       name: exception.name,
-      message: exception.message,
+      message: message,
       exception: exception,
       stack: exception.stack,
     });
   }
+
+  isUniqueConstraintException(exception: HttpException): boolean {
+    return exception.message.includes("Unique constraint failed on the fields");
+  }
+
+  getCustomMessageForException(exception: HttpException): string {
+    let message = exception.message;
+    message = (message.includes("build.update()")) ? "There is already a build with this ci build id."
+      : (message.includes("project.create()")) ? "Project exists with this name."
+        : (message.includes("user.create()")) ? "This user already exists." : message;
+    return message;
+  }
+
 }