Merge pull request #3 from lfir/feat/post-reqs

Add utility method to log and throw XMLParseException

Author: lfir

src/main/java/cf/maybelambda/httpvalidator/springboot/persistence/XMLErrorHandler.java

@@ -5,13 +5,57 @@
 import org.xml.sax.ErrorHandler;
 import org.xml.sax.SAXParseException;
 
+import javax.management.modelmbean.XMLParseException;
+
 /**
- * Custom error handler for XML schema validation errors.
+ * Custom error handler for XML schema validation errors. Also contains utility methods related to error handling.
  */
 public class XMLErrorHandler implements ErrorHandler {
     private static Logger logger = LoggerFactory.getLogger(XMLErrorHandler.class);
     private static final String logmsg = "Warning during Schema Validation of the datafile";
 
+    /**
+     * Functional interface representing a function that accepts one argument and produces a result,
+     * potentially throwing an exception during the process.
+     *
+     * <p>This interface is similar to {@link java.util.function.Function}, but it allows for checked
+     * exceptions to be thrown during the function application.
+     *
+     * @param <T> the type of the input to the function
+     * @param <R> the type of the result of the function
+     */
+    @FunctionalInterface
+    interface ThrowingFunction<T, R> {
+        R apply(T arg) throws Exception;
+    }
+
+    /**
+     * A utility method to apply a function that may throw an exception, with additional exception handling.
+     *
+     * <p>This method attempts to apply the provided function to the given argument. If an exception occurs,
+     * it logs the error message along with the exception and then throws an {@code XMLParseException} with
+     * the same data.
+     *
+     * @param <T>    the type of the input to the function
+     * @param <R>    the type of the result of the function
+     * @param f      the function to be applied, which may throw an exception
+     * @param arg    the argument to be passed to the function
+     * @param logger the logger to be used
+     * @param msg    the error message to be logged and included in the thrown {@code XMLParseException}
+     * @return the result of the function application
+     * @throws XMLParseException if the function throws any exception during its application
+     *
+     *  @see ThrowingFunction
+     */
+    static <T, R> R parseInputOrThrow(ThrowingFunction<T, R> f, T arg, Logger logger, String msg) throws XMLParseException {
+        try {
+            return f.apply(arg);
+        } catch (Exception e) {
+            logger.error(msg, e);
+            throw new XMLParseException(e, msg + "\n");
+        }
+    }
+
     /**
      * Handles warnings encountered during XML schema validation.
      * The exception is logged but not thrown again.

src/main/java/cf/maybelambda/httpvalidator/springboot/persistence/XMLValidationTaskDao.java

@@ -1,7 +1,6 @@
 package cf.maybelambda.httpvalidator.springboot.persistence;
 
 import cf.maybelambda.httpvalidator.springboot.model.ValidationTask;
-import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.slf4j.Logger;
@@ -35,6 +34,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static cf.maybelambda.httpvalidator.springboot.persistence.XMLErrorHandler.parseInputOrThrow;
 import static java.util.Objects.requireNonNull;
 
 /**
@@ -104,13 +104,7 @@ public XMLValidationTaskDao() throws ParserConfigurationException, SAXException,
      * @throws XMLParseException if parsing fails.
      */
     Document parseXMLInput(InputStream inputStream) throws XMLParseException {
-        try {
-            return this.xmlParser.parse(inputStream);
-        } catch (Exception e) {
-            String errmsg = "Failed to parse target XML content";
-            logger.error(errmsg, e);
-            throw new XMLParseException(e, errmsg + "\n");
-        }
+        return parseInputOrThrow(this.xmlParser::parse, inputStream, logger, "Failed to parse target XML content");
     }
 
     /**
@@ -151,7 +145,7 @@ synchronized Document getDocData() throws XMLParseException, FileNotFoundExcepti
      * @return The new validation task.
      * @throws XMLParseException if JSON content in the reqbody element cannot be parsed.
      */
-    private ValidationTask createVTaskFromNodes(NodeList validation) throws XMLParseException {
+    ValidationTask createVTaskFromNodes(NodeList validation) throws XMLParseException {
         MethodType method = null;
         String url = null;
         List<String> headers = new ArrayList<>();
@@ -174,13 +168,7 @@ private ValidationTask createVTaskFromNodes(NodeList validation) throws XMLParse
                 headers.add(content);
             }
             if (REQ_BODY_TAG.equals(name)) {
-                try {
-                    reqBody = this.mapper.readTree(content);
-                } catch (JsonProcessingException e) {
-                    String errmsg = "Invalid JSON content encountered in the data file";
-                    logger.error(errmsg, e);
-                    throw new XMLParseException(e, errmsg + "\n");
-                }
+                reqBody = parseInputOrThrow(this.mapper::readTree, content, logger, "Invalid JSON encountered in data file");
             }
             if (RES_TAG.equals(name)) {
                 resStatusCode = Integer.parseInt(attrs.getNamedItem(RES_SC_ATTR).getTextContent());