patch-resource/src/patch-resource.js

JSON Patch extension for Angular's ngResource module

const observers = [];

function patchResourceService($resource) {
    return function (host = '', params = {}, extensions = {}, ...rest) {
        let resource;

        if (extensions.patch) throw new Error('PatchResource: "Patch" is already extended with an action');
        extensions.patch = {
            method: 'PATCH',
            transformRequest: function (resourceObject) {
                const obj = observers.filter((_obj) => _obj.resourceObject === resourceObject)[0];
                let patch;

                if (!obj) throw new Error('No JSON Patch observer available for $patch');

                patch = window.jsonpatch.generate(obj.observer);
                return window.angular.toJson(patch);
            },
        };

        resource = $resource(host, params, extensions, ...rest);
        resource.__get = resource.get;

        resource.get = function () {
            const resourceObject = this.__get.apply(this, arguments);

            resourceObject.$promise.then(function () {
                observers.push({
                    resourceObject: resourceObject,
                    observer: window.jsonpatch.observe(resourceObject),
                });
            });

            return resourceObject;
        };

        return resource;
    };
}

window.angular
    .module('patchResource', ['ngResource'])
    .service('$patchResource', ['$resource', patchResourceService]);