


What is a Persister and When Would You Use One?
A persister is a class that stores and manages the state of an application. It is responsible for storing the data that the application needs to remember between sessions, such as user preferences or login information. The persister is typically used in conjunction with a unit of work, which is a pattern that allows you to perform a series of operations on a piece of data without committing the changes until you are ready.
Here are some key features of a persister:
1. State management: A persister manages the state of an application, which includes storing and retrieving data.
2. Unit of work: A persister is typically used in conjunction with a unit of work, which allows you to perform a series of operations on a piece of data without committing the changes until you are ready.
3. Data storage: A persister stores data in a persistent storage, such as a database or file system.
4. Data retrieval: A persister retrieves data from a persistent storage when it is needed.
5. Data validation: A persister may validate the data before storing it or after retrieving it to ensure that it is in a valid format.
6. Data cleanup: A persister may perform data cleanup operations, such as removing expired data or data that is no longer needed.
7. Transaction management: A persister may manage transactions, which allow you to perform multiple operations on a piece of data as a single unit of work.
8. Concurrency control: A persister may implement concurrency control mechanisms, such as locks or optimistic concurrency, to ensure that multiple users do not try to modify the same data at the same time.
Here are some examples of when you might use a persister:
1. User preferences: You might use a persister to store user preferences, such as their language or location, so that they are remembered between sessions.
2. Login information: You might use a persister to store login information, such as usernames and passwords, so that users do not have to enter them every time they log in.
3. Shopping cart: You might use a persister to store the items in a shopping cart so that they are remembered between pages.
4. Session state: You might use a persister to store session state, such as the current page or the user's selection, so that it is remembered between requests.
5. Caching: You might use a persister to cache frequently accessed data, such as frequently asked questions or popular articles, so that it can be retrieved quickly and easily.



