---
title: callables
sidebarTitle: callables
---

# `prefect.utilities.callables`



Utilities for working with Python callables.


## Functions

### `get_call_parameters` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L43" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_call_parameters(fn: Callable[..., Any], call_args: tuple[Any, ...], call_kwargs: dict[str, Any], apply_defaults: bool = True) -> dict[str, Any]
```


Bind a call to a function to get parameter/value mapping. Default values on
the signature will be included if not overridden.

If the function has a `__prefect_self__` attribute, it will be included as
the first parameter. This attribute is set when Prefect decorates a bound
method, so this approach allows Prefect to work with bound methods in a way
that is consistent with how Python handles them (i.e. users don't have to
pass the instance argument to the method) while still making the implicit self
argument visible to all of Prefect's parameter machinery (such as cache key
functions).

Raises a ParameterBindError if the arguments/kwargs are not valid for the
function


### `get_parameter_defaults` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L83" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_parameter_defaults(fn: Callable[..., Any]) -> dict[str, Any]
```


Get default parameter values for a callable.


### `explode_variadic_parameter` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L100" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
explode_variadic_parameter(fn: Callable[..., Any], parameters: dict[str, Any]) -> dict[str, Any]
```


Given a parameter dictionary, move any parameters stored in a variadic keyword
argument parameter (i.e. **kwargs) into the top level.

Example:

    ```python
    def foo(a, b, **kwargs):
        pass

    parameters = {"a": 1, "b": 2, "kwargs": {"c": 3, "d": 4}}
    explode_variadic_parameter(foo, parameters)
    # {"a": 1, "b": 2, "c": 3, "d": 4}
    ```


### `collapse_variadic_parameters` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L134" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
collapse_variadic_parameters(fn: Callable[..., Any], parameters: dict[str, Any]) -> dict[str, Any]
```


Given a parameter dictionary, move any parameters stored not present in the
signature into the variadic keyword argument.

Example:

    ```python
    def foo(a, b, **kwargs):
        pass

    parameters = {"a": 1, "b": 2, "c": 3, "d": 4}
    collapse_variadic_parameters(foo, parameters)
    # {"a": 1, "b": 2, "kwargs": {"c": 3, "d": 4}}
    ```


### `parameters_to_args_kwargs` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L178" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
parameters_to_args_kwargs(fn: Callable[..., Any], parameters: dict[str, Any]) -> tuple[tuple[Any, ...], dict[str, Any]]
```


Convert a `parameters` dictionary to positional and keyword arguments

The function _must_ have an identical signature to the original function or this
will return an empty tuple and dict.


### `call_with_parameters` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L201" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
call_with_parameters(fn: Callable[..., R], parameters: dict[str, Any]) -> R
```


Call a function with parameters extracted with `get_call_parameters`

The function _must_ have an identical signature to the original function or this
will fail. If you need to send to a function with a different signature, extract
the args/kwargs using `parameters_to_positional_and_keyword` directly


### `cloudpickle_wrapped_call` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L213" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
cloudpickle_wrapped_call(__fn: Callable[..., Any], *args: Any, **kwargs: Any) -> Callable[[], bytes]
```


Serializes a function call using cloudpickle then returns a callable which will
execute that call and return a cloudpickle serialized return value

This is particularly useful for sending calls to libraries that only use the Python
built-in pickler (e.g. `anyio.to_process` and `multiprocessing`) but may require
a wider range of pickling support.


### `parameter_docstrings` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L254" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
parameter_docstrings(docstring: Optional[str]) -> dict[str, str]
```


Given a docstring in Google docstring format, parse the parameter section
and return a dictionary that maps parameter names to docstring.

**Args:**
- `docstring`: The function's docstring.

**Returns:**
- Mapping from parameter names to docstrings.


### `process_v1_params` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L282" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
process_v1_params(param: inspect.Parameter) -> tuple[str, Any, Any]
```

### `create_v1_schema` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L313" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
create_v1_schema(name_: str, model_cfg: type[Any], model_fields: Optional[dict[str, Any]] = None) -> dict[str, Any]
```

### `parameter_schema` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L331" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
parameter_schema(fn: Callable[..., Any]) -> ParameterSchema
```


Given a function, generates an OpenAPI-compatible description
of the function's arguments, including:
    - name
    - typing information
    - whether it is required
    - a default value
    - additional constraints (like possible enum values)

**Args:**
- `fn`: The function whose arguments will be serialized

**Returns:**
- the argument schema


### `parameter_schema_from_entrypoint` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L357" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
parameter_schema_from_entrypoint(entrypoint: str) -> ParameterSchema
```


Generate a parameter schema from an entrypoint string.

Will load the source code of the function and extract the signature and docstring
to generate the schema.

Useful for generating a schema for a function when instantiating the function may
not be possible due to missing imports or other issues.

**Args:**
- `entrypoint`: A string representing the entrypoint to a function. The string
should be in the format of `module.path.to.function\:do_stuff`.

**Returns:**
- The parameter schema for the function.


### `generate_parameter_schema` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L391" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
generate_parameter_schema(signature: inspect.Signature, docstrings: dict[str, str]) -> ParameterSchema
```


Generate a parameter schema from a function signature and docstrings.

To get a signature from a function, use `inspect.signature(fn)` or
`_generate_signature_from_source(source_code, func_name)`.

**Args:**
- `signature`: The function signature.
- `docstrings`: A dictionary mapping parameter names to docstrings.

**Returns:**
- The parameter schema.


### `raise_for_reserved_arguments` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L447" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
raise_for_reserved_arguments(fn: Callable[..., Any], reserved_arguments: Iterable[str]) -> None
```


Raise a ReservedArgumentError if `fn` has any parameters that conflict
with the names contained in `reserved_arguments`.


### `expand_mapping_parameters` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L661" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
expand_mapping_parameters(func: Callable[..., Any], parameters: dict[str, Any]) -> list[dict[str, Any]]
```


Generates a list of call parameters to be used for individual calls in a mapping
operation.

**Args:**
- `func`: The function to be called
- `parameters`: A dictionary of parameters with iterables to be mapped over

**Returns:**
- A list of dictionaries to be used as parameters for each
call in the mapping operation


## Classes

### `ParameterSchema` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L238" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Simple data model corresponding to an OpenAPI `Schema`.


**Methods:**

#### `model_dump_for_openapi` <sup><a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/callables.py#L247" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
model_dump_for_openapi(self) -> dict[str, Any]
```
