A Gremlin (Groovy) webpack loader.

gremlin-loader allows you to define Gremlin queries in Groovy files and load them within your Node.js environment as JavaScript functions. Think about Webpack css-loader in module mode, but for loading Groovy files instead of CSS flles.

The loader returns an Object where keys are names of all the functions found in the parsed file and values are JavaScript functions that, when called, return an Object with two properties:

• bindings: an Object where keys are argument names of the function as defined in the Groovy file and values are all values passed when calling the JavaScript function
• gremlin: the full string representation of the function as defined in the Groovy file, with an extra line appended responsible for immediately calling that Groovy function with the above bindings when sent to Gremlin Server for execution

This loader is meant to be used server-side with babel-plugin-webpack-loaders.

This is highly experimental and shouldn't be used in production.

npm install gremlin-loader babel-plugin-webpack-loaders --save

To make babel-plugin-webpack-loaders work, your .babelrc file should resemble the following:

{
  "presets": ["es2015"],
  "plugins": [
    ["babel-plugin-webpack-loaders", {
      "config": "./webpack.config.babel.js",
      "verbose": false,
    }]
  ]
}

And the corresponding webpack.config.babel.js file:

const config = {
  output: {
    libraryTarget: 'commonjs2',
  },
  resolve: {
    extensions: ['', '.js', '.gremlin']
  },
  module: {
    loaders: [
      {
        test: /\.gremlin$/,
        loader: 'gremlin'
      }
    ]
  }
};

export default config;

Once configured, you can do the following:

queries.gremlin file:

def fetchAllByName = { userName ->
  g.V().has('name', userName)
}

application.js file:

import { fetchAllByName } from './queries';

const byNameQuery = fetchAllByName('Alice');
// byNameQuery is an object with 'gremlin' and 'bindings' keys:
// {
//   gremlin: 'def fetchAllByName = { userName ->  g.V().has(\'name\', userName)}\n;fetchAllByName(userName)',
//   bindings: { userName: 'Alice' }
// }

When used in conjunction with gremlin-javascript:

import { createClient } from 'gremlin';

const client = createClient();

const query = fetchAllByName('Alice');
client.execute(query, (err, results) => {
  // handle err or results
});

• full reusability of your Gremlin queries: anything you write in .gremlin (or .groovy) files is valid Gremlin-Groovy and can be copy/pasted in the Gremlin console or used in any other application
• automatic parameter bindings with explicit names by extracting the function signature, for better Gremlin server performance (no query recompilation) and security (no injection)
• you do not have to write/escape fat strings of Gremlin in your application, and you also get proper syntax highlighting for free in your IDE (because Gremlin is just Groovy)
• automatic reloading of your Node.js application on .gremlin file change