3 new Scala code patterns

Read about 3 new Scala code patterns we just added to our platform in our mission Codacy to support multiple coding languages effectively.

1. Avoid using DateTime.now without a timezone (Error Prone)

Using DateTime.now without specifying a timezone can lead to error prone code with regard to dealing with other timezones than those initially considered, as well as with daylight saving time.

For instance, the following example:

val now = DateTime.now

could easily be written as:

val now = DateTime.now(DateTimeZone.UTC)

2. Prefer using .nonEmpty (Code Style)

The collections libraries usually provide a method for determining if the iterable has, at least, one element, with:

val hasElements = SomeSequence.nonEmpty

This is a bit cleaner than verifying explicitly the length or the size:

val hasElements = SomeSequence.length > 0
 val hasElementsUsingSize = SomeSequence.size > 0

3. Prevent XML parsing attacks (Security)

XML External Entity (XXE) attacks can occur when an XML parser supports XML entities while processing XML received from an untrusted source.

Vulnerable Code:

SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
 parser.parse(inputStream, customHandler);

Solution using “Secure processing” mode:

SAXParserFactory spf = SAXParserFactory.newInstance();
 spf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
 SAXParser parser = spf.newSAXParser();
 parser.parse(inputStream, customHandler);

Solution disabling DTD:

SAXParserFactory spf = SAXParserFactory.newInstance();
 spf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
 SAXParser parser = spf.newSAXParser();
 parser.parse(inputStream, customHandler);

Enabling patterns with Codacy

When new patterns are added, they’re disabled for already existing projects.

To enable them for a project first head to the project and hit “Code Patterns” on the top right corner. You’ll be able to filter the patterns by language or category: