modal.Dict

class Dict(modal.object.Object)

Distributed dictionary for storage in Modal apps.

Dict contents can be essentially any object so long as they can be serialized by cloudpickle. This includes other Modal objects. If writing and reading in different environments (eg., writing locally and reading remotely), it’s necessary to have the library defining the data type installed, with compatible versions, on both sides. Additionally, cloudpickle serialization is not guaranteed to be deterministic, so it is generally recommended to use primitive types for keys.

Lifetime of a Dict and its items

An individual Dict entry will expire after 7 days of inactivity (no reads or writes). The Dict entries are written to durable storage.

Legacy Dicts (created before 2025-05-20) will still have entries expire 30 days after being last added. Additionally, contents are stored in memory on the Modal server and could be lost due to unexpected server restarts. Eventually, these Dicts will be fully sunset.

Usage

from modal import Dict

my_dict = Dict.from_name("my-persisted_dict", create_if_missing=True)

my_dict["some key"] = "some value"
my_dict[123] = 456

assert my_dict["some key"] == "some value"
assert my_dict[123] == 456

The Dict class offers a few methods for operations that are usually accomplished in Python with operators, such as Dict.put and Dict.contains. The advantage of these methods is that they can be safely called in an asynchronous context by using the .aio suffix on the method, whereas their operator-based analogues will always run synchronously and block the event loop.

For more examples, see the guide.

hydrate

def hydrate(self, client: Optional[_Client] = None) -> Self:

Synchronize the local object with its identity on the Modal server.

It is rarely necessary to call this method explicitly, as most operations will lazily hydrate when needed. The main use case is when you need to access object metadata, such as its ID.

Added in v0.72.39: This method replaces the deprecated .resolve() method.

ephemeral

@classmethod
@contextmanager
def ephemeral(
    cls: type["_Dict"],
    data: Optional[dict] = None,  # DEPRECATED
    client: Optional[_Client] = None,
    environment_name: Optional[str] = None,
    _heartbeat_sleep: float = EPHEMERAL_OBJECT_HEARTBEAT_SLEEP,
) -> Iterator["_Dict"]:

Creates a new ephemeral Dict within a context manager:

Usage:

from modal import Dict

with Dict.ephemeral() as d:
    d["foo"] = "bar"

async with Dict.ephemeral() as d:
    await d.put.aio("foo", "bar")

from_name

@staticmethod
def from_name(
    name: str,
    data: Optional[dict] = None,  # DEPRECATED
    *,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    environment_name: Optional[str] = None,
    create_if_missing: bool = False,
) -> "_Dict":

Reference a named Dict, creating if necessary.

In contrast to modal.Dict.lookup, this is a lazy method that defers hydrating the local object with metadata from Modal servers until the first time it is actually used.

d = modal.Dict.from_name("my-dict", create_if_missing=True)
d[123] = 456

delete

@staticmethod
def delete(
    name: str,
    *,
    client: Optional[_Client] = None,
    environment_name: Optional[str] = None,
):

clear

@live_method
def clear(self) -> None:

Remove all items from the Dict.

get

@live_method
def get(self, key: Any, default: Optional[Any] = None) -> Any:

Get the value associated with a key.

Returns default if key does not exist.

contains

@live_method
def contains(self, key: Any) -> bool:

Return if a key is present.

len

@live_method
def len(self) -> int:

Return the length of the Dict.

Note: This is an expensive operation and will return at most 100,000.

update

@live_method
def update(self, other: Optional[Mapping] = None, /, **kwargs) -> None:

Update the Dict with additional items.

put

@live_method
def put(self, key: Any, value: Any, *, skip_if_exists: bool = False) -> bool:

Add a specific key-value pair to the Dict.

Returns True if the key-value pair was added and False if it wasn’t because the key already existed and skip_if_exists was set.

pop

@live_method
def pop(self, key: Any) -> Any:

Remove a key from the Dict, returning the value if it exists.

keys

@live_method_gen
def keys(self) -> Iterator[Any]:

Return an iterator over the keys in this Dict.

Note that (unlike with Python dicts) the return value is a simple iterator, and results are unordered.

values

@live_method_gen
def values(self) -> Iterator[Any]:

Return an iterator over the values in this Dict.

Note that (unlike with Python dicts) the return value is a simple iterator, and results are unordered.

items

@live_method_gen
def items(self) -> Iterator[tuple[Any, Any]]:

Return an iterator over the (key, value) tuples in this Dict.

Note that (unlike with Python dicts) the return value is a simple iterator, and results are unordered.