treewalk example

treewalk

  /**
   * @param {object[]} dependencies A list of steps to do at each depth of the tree.
   * dependencies[0] is invoked first, then we call dependencies[1] on each child action. etc.
   * @param {function} dependencies.request A function that returns a promise.
   * @param {function:object[]} dependencies.onSuccess A function to call after the promise from dependencies.request finishes.
   *  This function should return a list of objects to invoke the next depth dependency on.
   * 
   * @param {function} onFinish What to do when everything node has been traversed.
   */
  DataLoader.walkTree = function(dependencies, onFinish) {
    var innerWalk;

    var counter = 0;
    var finalData = {};

    function checkCounter() {
      if (counter === 0) {

        if(_.isFunction(onFinish)) {
          onFinish(finalData);
        }
      }
    };
    
    innerWalk = function(dependencies, optData, optIndex) {
      var depth = optIndex || 0;
      var dependency = dependencies[depth];
      if (_.isUndefined(dependency)) {
        // handle null recursive case
        checkCounter();
        return;
      }
      var promise = dependency.request(optData);
      counter = counter + 1;

      promise.then(function onWalkSuccess(response) {
        counter = counter - 1;
        var success = dependency.onSuccess(response.obj, optData);
        success = _.isArray(success) ? success : [success];
        _.each(success, function(data) {
          innerWalk(dependencies, data, depth + 1);
        });
      }).fail(function onWalkFail(response) {
        counter = counter - 1;
        checkCounter();
      });
    };

    innerWalk(dependencies, finalData);
  };


//// Example of it in action:

      DataLoader.walkTree([{
        request: function(data) {
          return Deployment.list({environment: environment.name()});
        },
        onSuccess: function(deploymentNames, parent) {
          parent.deployments = _.map(deploymentNames, function(depName) {
            return {
              name: depName,
              environment: environment.name(),
              clusters: []
            };
          });
          return parent.deployments;
        }
      }, {
        request: function(parent) {
          return Cluster.list({environment: environment.name(), deployment: parent.name});
        },
        onSuccess: function(clusterNames, deployment) {
          _.each(clusterNames, function(clusterName) {
            
            var cluster = {
              environment: environment.name(),
              deployment: deployment.name,
              name: clusterName
            };
            deployment.clusters.push(cluster);
          });
        }        
      }], function done(data) {
        window.console.log('data = ', data);

      });