ggranum/java-builder-gen

IntelliJ plugin for generating builders from simple model classes.

IntelliJ Plugin for generating classes that follow the Builder pattern

Builder Generator for immutable POJO models.

What's the point of a builder pattern if it isn't immutable? If your model is immutable, what's the point of getter access?

Create a builder from your final fields. Add your @Immutable annotation of choice and make the class final. Done.

Alt-Enter ( "Show Intention Actions" ) -> Generate Builder. If the menu entry is missing, be sure the cursor is on a blank line within the class.

Or invoke via right-click menu

ONLY SUPPORTS FINAL FIELDS

Overwrites on each invocation!.

Be careful. Replacing this with 'update' is high priority, but also quite complex.

Features

• Add Jackson Annotations to your builders. Parse from JSON straight into an immutable POJO.
• Auto generate toJson and fromJson methods that use Jackson to marshal your object.
• Generates Copy constructor and example usage code comment on builder constructor.
• Optionally applies Hibernate Validations, with the use of the Uttu project ( https://github.com/ggranum/uttu )

Adds a 'Generate Builder' option to the actions menu for a class.

Use

Add Google's immutables classes to your dependencies:

For Gradle:

dependencies {
    implementation "com.google.guava:guava:27.1-jre"
}

Create a simple class with a handful of final fields and no constructor to demonstrate, then hit Alt-Enter ( "Show Intention Actions" ) -> Generate Builder.

If the menu entry is missing, be sure the cursor is on a blank line within the class.

Add Jackson Annotations

You'll need to have the Jackson libraries in your project's dependencies for Jackson Annotations and / or toJson/fromJson methods.

For Gradle:

dependencies {
    implementation "com.fasterxml.jackson.core:jackson-annotations:2.9.8";
    implementation "com.fasterxml.jackson.core:jackson-databind:2.9.8";
}

(jackson-databind actually already causes jackson-annotations to be included, but for completeness we depend on both in the above)

This option causes the Jackson annotations required for marshalling a JSON object via the Builder itself to be added to the Class as well as the builder field declarations.

Generate toJson and fromJson methods

These options requires the 'Generate Jackson Annotations' method to be enabled.

Enabling both these options will create the methods:

public String toJson(ObjectMapper mapper);
public static YourClass fromJson(ObjectMapper mapper, String json);

We require Jackson's mapper class to be provided so that you may create one and reuse it, perhaps by injecting it into your calling classes via Guice, or however you so choose.

The ObjectMapper is expensive to create, and thread safe. So, as per Jackson Databind recommendations, we don't want to create a new one every time we marshal or unmarshal a single object.

About

java-builder-gen's Issues

research: Investigate method for preventing overwriting hand-modified builders

Goal: Show an alert if the user is about to overwrite a builder that has been modified since it was first generated.

Perhaps adding a hash via annotations or comments.

Further, we might be able to move forward after simple alerts to preserving custom changes.

feat(UI,Generate): Generate JSON output example in class comment

It would be nice if we could generate an example of the expected JSON output/input at Generate Builder time.

defect(copy): Copy method does not handle Optionals correctly.

Generate a new Builder with the 'copy' method option, on any class with a Field of type Optional.

feat(ui, builder): Option for 'add' methods on Maps and Lists

Provide an option to allow users to enable addFoo methods for Collection fields.

For example, if I have:

public final List<Person> people;

the builder should gain the methods:

public Builder people(List<Person> people){ ... }
public Builder addToPeople(Person aPeople){ ... }

Super extra credit would be to add an annotation to the public field to allow setting the addFoo naming.

defect(generate): Maps are not immutable by default

The constructor assignment needs to be wrapped in an ImmutableMap.copyOf, as with List

feat(generate): Should be able to Generate method and assignment for a single field.

User should be able to invoke builder action on a single field.

defect(Generate): Generated Long values need '0L', not '0'.

Creates compile error.