Compile time Morphia validation

Latest Version

The latest release version is 0.1.0 and is available on Maven Central at the following coordinates:

groupId: me.shils, artifactId: morphia-type-checker, version: 0.1.0

A quick example

Within the Morphia library, there are many places where String objects are used to refer to a field of a class. These usages aren't normally validated by the compiler; for example, the following code compiles without any indication that the User class doesn't have a userd field:

import org.mongodb.morphia.annotations.*
import groovy.transform.CompileStatic
import org.bson.types.ObjectId

@Entity
@Indexes(@Index(fields = @Field('userd')))
@CompileStatic
class User {
  @Id
  ObjectId id
  int userId
}

The error would be discovered at runtime, hopefully before it reached a production environment. If only the compiler knew that 'userd' was supposed to be the name of a field of the User class...

Fortunately, using Groovy type checking extensions, we can make the compiler aware of what we already know. If we apply the EntityTypeCheckingExtension to our User class,

@Entity
@Indexes(@Index(fields = @Field('userd')))
@CompileStatic(extensions = 'me.shils.morphia.EntityTypeCheckingExtension')
class User {
  @Id
  ObjectId id
  int userId
}

our code will fail compilation with the following error:

[Static type checking] - No such persisted field: userd for class: User

Pre-Usage

To use Morphia Type Checker, you'll first need it on your compiler classpath. You can add it as a dependency with Maven or Gradle, or build the jar from source if you prefer.

You must also be using (at the minimum):

Java: 7

Groovy: 2.4.0

Morphia: 0.107

Usage

The easiest way to validate your Morphia Entities (classes annotated with @Entity) and DAOs (classes that implement the DAO interface) at compile time is by using a config script. Just add an instance of MorphiaTypeCheckingCustomizer to the bound configuration variable and the appropriate type checking extensions will be applied to your Entities and DAOs:

import me.shils.morphia.MorphiaTypeCheckingCustomizer

configuration.addCompilationCustomizers(new MorphiaTypeCheckingCustomizer())

Alternatively, you can add the appropriate extensions to your statically type checked classes yourself - EntityTypeCheckingExtension for Entities, and DAOTypeCheckingExtension for DAOs.

Extensions

The following type checking extensions are used to validate the usage of strings referencing fields in different contexts.

DAOTypeCheckingExtension

When applied to DAOs, this extension validates:

• arguments to Query methods criteria, field, filter, and order
• arguments to UpdateOperations methods add, addAll, dec, inc, max, min, removeAll, removeFirst, removeLast, set, setOnInsert, and unset

It is assumed that queries and updates within the DAO target the DAO's entity class.

EntityTypeCheckingExtension

When applied to Entities, this extension validates:

• value members of @Index and @Field

Dependency Snippets

Maven

<dependency>
  <groupId>me.shils</groupId>
  <artifactId>morphia-type-checker</artifactId>
  <version>0.1.0</version>
</dependency>

Gradle

dependencies {
  compile 'me.shils:morphia-type-checker:0.1.0'
}

Building from source

To build from source, just clone this repo and run ./gradlew build from the root directory of the project.