add option to pass a function to store.$patch()

[unstoppablecarl]

Clear and concise description of the problem

There is no way to intercept and override the store.$patch() process.

Sometimes the order and grouping that state data is loaded into a pinia store matters a lot for computed properties and reactivity. Currently there is no way to control this as data is just sent to store.$patch(data). It is possible to re-order the keys of an object via the serializer option but, this does not allow control of data patch grouping.

There is currently no way to pick/omit object data within an array when hydrating.

There is also no way to control the order that different pinia stores are patched. I have not run into a problem that required this yet but, I suspect it could easily have the same ordering problem. I am not proposing a solution to this case but wanted to mention it for discussion.

Suggested solution

see: https://pinia.vuejs.org/core-concepts/state.html#Mutating-the-state

Example of new plugin option hydrate.

import {defineStore, StateTree, Store} from 'pinia'

defineStore('store', {
  state: () => ({
    first: '',
    second: '',
  }),
  persist: {
      hydrate: (deserialized: StateTree) => (store: Store) => {
        store.$patch({
          first: deserialized.first
        })

        store.$patch({
          second: deserialized.second
        })

      }
    },
  }
})

Changes made in core.ts

//
const deserialized = serializer.deserialize(fromStorage)
      const picked = pick
        ? deepPickUnsafe(deserialized, pick)

        : deserialized
      const omitted = omit
        ? deepOmitUnsafe(picked, omit)
        : picked
      // changes below
      if (hydrate) {
        store.$patch(hydrate(omitted))
      } else {
        store.$patch(omitted)
      }
//

Alternative

No response

Additional context

No response

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