Book's nested JSON entries & REST API (POST): Implement support

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/java/com/fjordtek/bookstore/web/BookBasePathAwareController.java

@@ -0,0 +1,132 @@
+//Pekka Helenius <fincer89@hotmail.com>, Fjordtek 2020
+
+package com.fjordtek.bookstore.web;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.rest.webmvc.BasePathAwareController;
+import org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fjordtek.bookstore.model.Book;
+import com.fjordtek.bookstore.model.BookEventHandler;
+import com.fjordtek.bookstore.model.BookRepository;
+import com.fjordtek.bookstore.model.CategoryRepository;
+
+/**
+ *
+ * This class implements a custom Spring REST controller for the bookstore,
+ * overriding specific REST API controller end point handlings
+ * with @BasePathAwareController annotation.
+ * <p>
+ * @RepositoryRestController
+ * To extend default REST API end point request handling, add a class
+ * with this annotation instead.
+ *
+ * @author Pekka Helenius
+ */
+
+@BasePathAwareController
+public class BookBasePathAwareController {
+
+	@Autowired
+	private BookRepository bookRepository;
+
+	@Autowired
+	private CategoryRepository categoryRepository;
+
+	private BookAuthorHelper bookAuthorHelper;
+	private BookEventHandler bookEventHandler;
+
+	private HttpServerLogger httpServerLogger = new HttpServerLogger();
+
+	/*
+	 * This method MUST exist with Autowired annotation. Handles autowiring of external classes.
+	 * If this method is not defined, they are not found by this controller class (are null).
+	 */
+	@Autowired
+	private void instanceAttributeController(
+			BookAuthorHelper bookAuthorHelper,
+			BookEventHandler bookEventHandler
+			) {
+		this.bookAuthorHelper = bookAuthorHelper;
+		this.bookEventHandler = bookEventHandler;
+	}
+
+	@RequestMapping(
+			value    = "booklist",
+			method   = RequestMethod.POST,
+			consumes = "application/json",
+			produces = "application/hal+json"
+			)
+	public ResponseEntity<?> bookAddJSONFormPost(
+			@RequestBody JsonNode bookJsonNodeEntity,
+			PersistentEntityResourceAssembler bookAssembler,
+    		HttpServletRequest requestData,
+			HttpServletResponse responseData
+			) {
+
+		try {
+
+			/*
+			 * Map JSON input string to Book entity object.
+			 * Nested data is not mapped.
+			 */
+			ObjectMapper jsonMapper = new ObjectMapper();
+			Book bookJ = jsonMapper.readValue(bookJsonNodeEntity.toString(), Book.class);
+
+			// Nested data: Determine nested JSON keys & their values
+			String authorFirstName = bookJsonNodeEntity.get("author").get("firstname").textValue();
+			String authorLastName  = bookJsonNodeEntity.get("author").get("lastname").textValue();
+			String categoryName    = bookJsonNodeEntity.get("category").get("name").textValue();
+
+			/*
+			 *  Treat nested JSON keys & values in a special way. Since input
+			 *  JSON data may lack some information to form a proper object,
+			 *  we need to use sophisticated methods to find and set missing
+			 *  attribute values properly for the Book entity object.
+			 */
+
+			// These must be set anyway, otherwise we get an error.
+			bookJ.setAuthor(null);
+			bookJ.setCategory(null);
+
+			if (authorFirstName != null && authorLastName != null) {
+				bookJ.setAuthor(
+						bookAuthorHelper.detectAndSaveAuthorByName(authorFirstName, authorLastName)
+						);
+			}
+			if (categoryName != null) {
+				bookJ.setCategory(
+						categoryRepository.findByNameIgnoreCaseContaining(categoryName).get(0)
+						);
+			}
+
+			// Save book and send JSON HAL response to the client
+			bookRepository.save(bookJ);
+
+			// Manually call a book event handler. Is there a better way to do this?
+			bookEventHandler.handleAfterCreate(bookJ);
+
+			httpServerLogger.log(requestData, responseData);
+
+			// return object type: PersistentEntityResource
+			return ResponseEntity.ok(bookAssembler.toFullResource(bookJ));
+
+		} catch (Exception e) {
+			e.printStackTrace();
+			httpServerLogger.log(requestData, responseData);
+			return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
+		}
+	}
+
+	// TODO implement a custom method for handling PUT request methods with nested JSON data
+}