WebApps 2

Key-value Data Store

Data in a key-value data store is stored and retrieved using a key that uniquely identifies the record.

API

The data storage API is available in WebApps and RESTApps.

// retrieve an instance of the storage API
const storage = require('storage');
// get a key-value store
// if no store exists with the provided name, one will be created
// (note: the name must also be explicitly registered in the app's manifest.json)
const keyValueStore = storage.getKeyValueDataStore('myStore');

API variants [@since 5.2]

The data storage API is available in two variants. One is callback-based whereas the other is callback-free. Please note that both variants execute synchronously, which probably makes the callback-free approach easier to work with.

Switch to callback-free API documentation

put(key, data, callback)

Stores data associated with a key

Argument	Description
`key`	A key to uniquely identify the record
`data`	JSON data to store
`callback`	Called after execution. The first parameter of the callback will contain an error object if an error occurred, `undefined` otherwise. The second parameter will contain the current data stored on the key.

const config = {
   name: 'Foo',
   title: 'Bar'
};

keyValueStore.put('config', config, (err, data) => {
   if (err) {
   // handle error
   }
   // data --> 
   {
      dsid: 'config', 
      name: 'Foo', 
      dstimestamp: 1554472667609, 
      title: 'Bar'
   }
});

If a property is set to null, the property will be removed

get(key, callback)

Gets data associated with a key

Argument	Description
`key`	A key to retrieve data from
`callback`	Called after execution. The first parameter of the callback will contain an error object if an error occurred, `undefined` otherwise. The second parameter will contain the data associated with the key.

keyValueStore.get('config', (err, data) => {
   if (err) {
   // handle error
   }
   res.json(data);
});

remove(key, callback)

Removes data associated with a key

Argument	Description
`key`	A key to identify data to remove
`callback`	Called after execution. The first parameter of the callback will contain an error object if an error occurred, `undefined` otherwise. The second parameter will contain the removed data.

keyValueStore.remove('config', (err, data) => {
   if (err) {
   // handle error
   }
   // ...
});