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
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
foo = new Ground.Collection('test');
foo.observeSource(bar.find());
Meteor.setTimeout(() => {
// Stop observing - keeping all documents as is
foo.stopObserver();
}, 1000);Limiting the stored data
If you want to clean up the storage and eg. have it match the current subscription, now you can:
foo.keep(bar.find());This will discard all documents not in the subscribed data
Limit the data stored locally
foo.keep(bar.find({}, { limit: 30 }));This will discard all but 30 documents
Limit the data stored locall using multiple cursors
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
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.
GroundLegacy = {
Collection: class GroundLegacy extends Ground.Collection {
constructor(collection, options) {
if (!(collection instanceof Mongo.Collection)) {
throw new Error('GroundLegacy requires a Mongo.Collection');
}
if (options.cleanupLocalData !== false) {
throw new Error('GroundLegacy requires cleanupLocalData to be false');
}
// Create an instance of ground db
super(collection._name);
this.mongoCollection = collection;
collection.grounddb = this;
// Observe on the whole collection
this.observeSource(collection.find());
// Store super
collection.orgFind = collection.find;
collection.orgFindOne = collection.findOne;
// Overwrite collection finds using the grounded data
collection.find = (...args) => {
return this.find(...args);
};
collection.findOne = (...args) => {
return this.findOne(...args);
};
}
removeLocalOnly() {
// Remove all documents not in current subscription
this.keep(this.mongoCollection.orgFind());
}
},
};More
Read about:
- Events in Ground DB
Contributions
Feel free to send issues, pull requests all is wellcome
Kind regards Morten