Opening Documents

Documents is the entry point. Open a document directly on the default store, or open a named Collection first when a set of documents needs its own MMKV file.

The default store

Documents.document<T>(key) is the common case — it opens (get-or-open, not "create anew") the document under key in the default store, with no config required:

@Serializable
data class Note(val title: String = "", val body: String = "", val done: Boolean = false)

val note = Documents.document<Note>("note-1")

A configuration block is optional and, today, only exposes dispatcher — the dispatcher used to collect flow()/stateFlow() (see Reactivity):

val note = Documents.document<Note>("note-1") {
    dispatcher = Dispatchers.Default // this is already the default
}

Collections — a separate MMKV file

Reach for Documents.collection(name) only when a set of documents needs its own file — a wipe-on-logout cache, per-user scoping, or an encryption boundary:

val drafts = Documents.collection("drafts") {
    dispatcher = Dispatchers.Default
}
val draft = drafts.document<Note>("draft-1")

See Collections & Testing for the single-process constraint that applies to every collection, including the default store.

The reserved key separator

Internally, every document is decomposed into one storage key per field, keyed {document}::{field} (see Field Decomposition). Because :: is reserved for that purpose, a document key containing it is rejected with an IllegalArgumentException — choose ordinary identifiers like "note-1" or "user".

No setup ceremony

MMKV initializes itself the first time it's needed — on Android via androidx.startup, on iOS via an internal call using the in-process sandbox path. You never call MMKV.initialize() and never pass a Context; the first Documents.document(...) or Documents.collection(...) call is enough.