Connecting stores to each other

Most real-world applications contain multiple stores which need to be linked to properly react to model changes.

To make your stores interconnect, fritz2 offers the OfferingHandler, a type of handler that doesn’t just take data as an argument but also offers data on a new Flow. The offered data can then be picked up and handled as usual.

Create such handler by calling the handleAndOffer() function instead of the handle() function, but add the offered data type to the type brackets:

val personStore = object : RootStore<Person>(Person(...)) {
    val save = handleAndOffer<Person> { person ->
        // saves the current Person
        offer(person) 
        person // return unchanged person
    }
}

The OfferingHandler named save offers the saved Person on its Flow. Another store can be setup to handle this Person by connecting the handlers:

val personStore = ... //see above

val personListStore = object : RootStore<List<Person>>(emptyList<Person>()) {
    val add = handle<Person> { list, person ->
       console.log("add new person: $person")
       list + person
    }
}

// don't forget to connect the handlers
personStore.save handledBy personListStore.add

After connecting these two stores via their handlers, a saved Person will also be added to the list in personListStore. All depending components will be updated accordingly.

To see a complete example visit our validation example which uses connected stores and validate a Person before adding it to a list of Persons.