ground:db

GroundDB is a fast and thin layer providing Meteor offline database - Taking cloud data to the ground.

Features

This version of GroundDB is a caching only storage - meaning it does not support resuming of method calls/cross tab updates etc. But it's faster and async supporting local storages like:

• localstorage
• indexeddb
• websql

* SQLite (on cordova)

It's using localforage with some minor modifications - hopefully we can use localForage via npm in the future

Notes about migration to GroundDB II

Usage

A pure offline collection

1  foo = new Ground.Collection('test');

Ground.Collection is client-side only and depends on LocalCollection for now

Get documents and updates from a Meteor Mongo Collection via DDP

1  foo = new Ground.Collection('test');
2
3  foo.observeSource(bar.find());
4
5  Meteor.setTimeout(() => {
6    // Stop observing - keeping all documents as is
7    foo.stopObserver();
8  }, 1000);

Limiting the stored data

If you want to clean up the storage and eg. have it match the current subscription, now you can:

1  foo.keep(bar.find());

This will discard all documents not in the subscribed data

Limit the data stored locally

1  foo.keep(bar.find({}, { limit: 30 }));

This will discard all but 30 documents

Limit the data stored locall using multiple cursors

1  foo.keep(bar.find({ type: 'a' }, { limit: 30 }), bar.find({ type: 'b' }, { limit: 30 }));

This will keep at max 60 documents 30 documents of each type "a"/"b"

Clear the storage

1  foo.clear();

This will empty the in memory and the local storage

Need a near backwards compatible solution?

This example behaves much like the previous version of ground db regarding caching a Mongo.Collection - This class inforces a manual clean up. Calling removeLocalOnly() will keep only the documents in the Mongo.Collection.

1GroundLegacy = {
2  Collection: class GroundLegacy extends Ground.Collection {
3    constructor(collection, options) {
4      if (!(collection instanceof Mongo.Collection)) {
5        throw new Error('GroundLegacy requires a Mongo.Collection');
6      }
7      if (options.cleanupLocalData !== false) {
8        throw new Error('GroundLegacy requires cleanupLocalData to be false');
9      }
10
11      // Create an instance of ground db
12      super(collection._name);
13
14      this.mongoCollection = collection;
15
16      collection.grounddb = this;
17
18      // Observe on the whole collection
19      this.observeSource(collection.find());
20
21      // Store super
22      collection.orgFind = collection.find;
23      collection.orgFindOne = collection.findOne;
24
25      // Overwrite collection finds using the grounded data
26      collection.find = (...args) => {
27        return this.find(...args);
28      };
29
30      collection.findOne = (...args) => {
31        return this.findOne(...args);
32      };
33    }
34
35    removeLocalOnly() {
36      // Remove all documents not in current subscription
37      this.keep(this.mongoCollection.orgFind());
38    }
39  },
40};

More

Read about:

• Events in Ground DB

Contributions

Feel free to send issues, pull requests all is wellcome

Kind regards Morten