q42:pending-changes

Let's your know when there are pending changes (inserts/updates and removes) on individual documents and collections as a whole. ie. when the change hasn't been confirmed by the server yet.

See this demo, which has an artificially induced delay of 3 seconds.

Install

$ meteor add q42:pending-changes

Usage

Say you have a collection of tasks:

Tasks = new Mongo.Collection('tasks');

The tasks are displayed as a list of tasks

<ul>
  {{#each tasks}}
    {{> task}}
  {{/each}}
</ul>

<template name="task">
  <li>
    {{text}}
    
    {{#if isSaving }}
        <span style="background-color: yellow; font-size: 80%;">saving...</span>
    {{/if}}
  </li>
</template>

Check if the task has pending changes:

  Template.task.helpers({
    isSaving: function() {
      return Tasks.hasPendingChanges(this._id);
    }
  });

API

<collection>.hasPendingChanges(<id>)

Check if the specified document has outstanding changes, ie updates that have not been confirmed by the server.

<collection>.hasPendingChanges()

If no id is passed, check if <collection> as a whole has any outstanding changes, ie updates that have not been confirmed by the server.

How it works

Internally, it keeps a reactive-dict to track each modified document by id. It does that by increasing a number when the insert/update/remove is initiated and it decreases that number again when the modification is confirmed (ie. when the callback returns). When the number of outstanding modifications reaches 0, you know that there are no pending changes anymore.

_id required

This package uses the _id field to track indiviual documents. This means that to track inserts you'll need to pass an _id field when inserting. For example:

Tasks.insert({
  _id : Random.id(),
  text: text
});

Version history

v0.0.4

• get() and getTotal() have been merged into 1 get() method. It reports the total # of changes when undefined or null is passed
• pending changes is only reported as a boolean instead of the # of pending changes
• add method to Mongo.Collection: .hasPendingChanges() This is the only api you'll need
• log warning if document is not trackable (no _id)
• move total # of pending changes per collection out of the dictionary and use a ReactiveVar instead

v0.0.3

First working public version