In volt, all models automatically save any changes back to their persistor. For example, if we change a name property on a model in store, it will automatically sync to the database and any other clients. Unlike other frameworks, there is no need to call save, models sync as soon as properties are changed.
store._items.first.then do |item|
item._name = 'New Item Name'
# ...syncs back to db
end
As another example, if we change an index property on params, the url is updated as soon as index is changed:
params._index = 20
# ...url is updated
Because the store collection is automatically synced to the backend, any change to a model's property will result in all other clients seeing the change immediately. Often this is not the desired behavior. To facilitate building CRUD apps, Volt provides the concept of a "buffer". A buffer can be created from one model and will not save data back to the model it was created from (the backing model) until .save! is called on the buffer. This lets you create a form that's not saved until a submit button is pressed.
store._items << {name: 'Item 1'}
store._items[0].then do |item1|
item1_buffer = item1.buffer
item1_buffer._name = 'Updated Item 1'
item1_buffer._name
# => 'Updated Item 1'
item1._name
# => 'Item 1'
item1_buffer.save!
item1_buffer._name
# => 'Updated Item 1'
item1._name
# => 'Updated Item 1'
end
#save! on buffer also returns a promise that will resolve when the data has been saved back to the server.
item1_buffer.save!.then do
puts "Item 1 saved"
end.fail do |err|
puts "Unable to save because #{err}"
end
Calling .buffer on an existing model will return a buffer for that model instance. If you call .buffer on a Volt::ArrayModel, you will get a buffer for a new item in that collection. Calling .save! will then add the item to that sub-collection as if you had done << or create to push the item into the collection.