Reference

MonaDB

monadb.open(path=None, *, durable=True) -> Database

Opens a database. path of None gives an in-memory database; otherwise the file is created if it does not exist.

Argument	Meaning
`path`	file path, or `None` for in-memory
`durable`	`False` relaxes commit durability, for bulk loads

Database

A Mapping[str, Collection], and a context manager that closes on exit.

Operation	Meaning
`db[name]`	a collection handle; auto-vivifying, never raises
`name in db`	whether the collection exists on disk
`list(db)`, `iter(db)`	collection names, sorted
`len(db)`	number of collections
`del db[name]`	drops the collection; `KeyError` if absent
`db.collection(name, model=None)`	a handle, optionally bound to a type
`db.close()`	closes the database

db[name] returns a handle without creating anything — the table appears on the first write. So a collection that has never been written reads as empty and does not appear in list(db).

Collection

A MutableMapping. Every method below the divider comes from the ABC.

Operation	Meaning
`c[key]`	the document; `KeyError` if absent
`c[key] = doc`	upsert — assignment overwrites
`del c[key]`	delete; `KeyError` if absent
`key in c`	membership
`len(c)`	number of documents
`iter(c)`	keys, in key order
`reversed(c)`	keys, descending
`c.keys()`	keys — a snapshot iterator
`c.values()`	documents — a snapshot iterator
`c.items()`	`(key, document)` — a snapshot iterator
`c.range(start, stop)`	`(key, document)` for `start <= key < stop`; `None` is unbounded
`c.prefix(p)`	`(key, document)` for keys beginning with `p`
`c.first()`	smallest `(key, document)`, or `None`
`c.last()`	largest `(key, document)`, or `None`
—
`c.get(key, default)`
`c.pop(key[, default])`
`c.popitem()`
`c.setdefault(key, default)`
`c.update(mapping)`	one commit for the whole mapping
`c.clear()`

Keys

Keys are of type: str, int, bytes, or a flat tuple of those. Ordering is int < str < bytes, componentwise for tuples. "a" and ("a",) are the same key.

Using float, bool, None, or nested tuples raise TypeError; an int outside 64 bits will raise a ValueError.

Documents

Documents are mappings whose values are None, bool, int, float, str, bytes, datetime, list, or a nested mapping. Datetimes store at millisecond precision, and naive ones are treated as UTC.

Exceptions

Exception	Raised when
`monadb.Error`	any storage fault, or use of a closed database
`KeyError`	missing key, or dropping a missing collection
`TypeError`	bad key type, non-mapping document, unsupported value type
`ValueError`	int out of range, or an empty collection name

Differences from Dict

Iteration is key order, not insertion order.
Keys are restricted to str | int | bytes | tuple.
Values must be mappings.
keys(), values(), items() are snapshot iterators, not live views.
"a" and ("a",) are the same key.