Transaction specification

Transaction Specification

Revision History

Version	User	Date	Notes
0.1	Milko Venkov	Aug 30, 2018	Initial Draft
0.2	Milko Venkov	Sep 04, 2018	Transaction state

1. Overview

Objectives

igx-transaction should be able to plug between given component and its data source. While plugged in igx-transaction should collect all the transactions performed in the component without send them to the data source. igx-transaction should be able to update the data source and commit all the transactions when needed.

2. User Stories

As an end user, I want

there is no end users stories as igx-transaction should be an Angular Service.

Developer Stories

As a developer, I want to

be able to enable transaction on a given component
be able to retrieve all the transactions - transaction log
be able to get updated state of the data including all transactions in the transaction log
be able to update data source with all the transactions currently in the transaction log
be able to undo the last change
be able to redo the change that was undone
be able to reset all the transactions in the transaction log

3. Functionality

3.1. End User Experience

3.2. Developer Experience

Developers are able to inject the igx-transaction service. Then developers should be able to add transaction to the transaction log. After some transactions are added developers should be able to retrieve updated data source state, including all transactions in the transaction log; update the data source when needed; reset all the transactions in the transaction log; perform undo and redo actions.

Here is what will happen with transaction state when new transactions is added:

Add transaction type - when adding such a transaction one should not provide initialValue. After successfully adding of such transaction it will be reflected in aggregated state like Add transaction type. If such a transaction is then added with Delete transaction type it will be removed from aggregated state. Adding of Add transaction type with id which already exists in aggregated state will throw an exception;
Update transaction type - when adding such a transaction one should provide initialValue. After successfully adding of such transaction it will be reflected in aggregated state like Update transaction type. One can also update Add transaction type - this will be reflected in aggregated state like Add transaction type, as well as Update transaction type - this will remain like Update transaction type in aggregated state. If one tries to update Delete transaction type an exception will be thrown.
Delete transaction type - when adding such a transaction one should provide initialValue. After successfully adding of such transaction it will be reflected in aggregated state like Deleted transaction type. One can also delete Add transaction type, this will remove the record from the aggregated state. One can also delete Update transaction type, this will change the aggregated type to Delete. If one tries to delete Delete transaction type an exception will be thrown.

Here is visual representation of all possible transactions paths.

3.3. API

Methods

ITransaction

Name	Description	Parameters
add	Adds provided transaction with originalValue if any	transaction, originalValue
getLastTransactionById	Returns last transaction related to the passed id	id
getTransactionLog	Returns an array of all transactions	-
undo	Remove the last transaction if any	-
redo	Applies the last undone transaction if any	-
currentState	Returns a map of actual state for each changed item	-
update	Applies all changes for all changed items in the provided data	data
reset	Clears all transactions	-