prefect.utilities.templating

Functions

determine_placeholder_type ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L52" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

determine_placeholder_type(name: str) -> PlaceholderType

Determines the type of a placeholder based on its name.

Args:

• name: The name of the placeholder

Returns:

• The type of the placeholder

find_placeholders ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L72" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

find_placeholders(template: T) -> set[Placeholder]

Finds all placeholders in a template.

Args:

• template: template to discover placeholders in

Returns:

• A set of all placeholders in the template

apply_values ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L129" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

apply_values(template: T, values: dict[str, Any], remove_notset: bool = True, warn_on_notset: bool = False, skip_prefixes: Optional[list[str]] = None) -> Union[T, type[NotSet]]

Replaces placeholders in a template with values from a supplied dictionary.

Will recursively replace placeholders in dictionaries and lists.

If a value has no placeholders, it will be returned unchanged.

If a template contains only a single placeholder, the placeholder will be fully replaced with the value.

If a template contains text before or after a placeholder or there are multiple placeholders, the placeholders will be replaced with the corresponding variable values.

If a template contains a placeholder that is not in values, NotSet will be returned to signify that no placeholder replacement occurred. If template is a dictionary that contains a key with a value of NotSet, the key will be removed in the return value unless remove_notset is set to False.

Args:

• template: template to discover and replace values in
• values: The values to apply to placeholders in the template
• remove_notset: If True, remove keys with an unset value
• warn_on_notset: If True, warn when a placeholder is not found in values
• skip_prefixes: If provided, placeholders whose names start with any of these prefixes will be left untouched in the template.

Returns:

• The template with the values applied

resolve_block_document_references ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L255" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

resolve_block_document_references(template: T, client: Optional['PrefectClient'] = None, value_transformer: Optional[Callable[[str, Any], Any]] = None) -> Union[T, dict[str, Any]]

Resolve block document references in a template by replacing each reference with its value or the return value of the transformer function if provided.

Recursively searches for block document references in dictionaries and lists.

Identifies block document references by the as dictionary with the following structure:

{
    "$ref": {
        "block_document_id": <block_document_id>
    }
}

where <block_document_id> is the ID of the block document to resolve.

Once the block document is retrieved from the API, the data of the block document is used to replace the reference.

Accessing Values:

To access different values in a block document, use dot notation combined with the block document's prefix, slug, and block name.

For a block document with the structure:

{
    "value": {
        "key": {
            "nested-key": "nested-value"
        },
        "list": [
            {"list-key": "list-value"},
            1,
            2
        ]
    }
}

examples of value resolution are as follows:

1. Accessing a nested dictionary: Format: prefect.blocks.<block_type_slug>.<block_document_name>.value.key Example: Returns {"nested-key": "nested-value"}

2. Accessing a specific nested value: Format: prefect.blocks.<block_type_slug>.<block_document_name>.value.key.nested-key Example: Returns "nested-value"

3. Accessing a list element's key-value: Format: prefect.blocks.<block_type_slug>.<block_document_name>.value.list[0].list-key Example: Returns "list-value"

Default Resolution for System Blocks:

For system blocks, which only contain a value attribute, this attribute is resolved by default.

Args:

• template: The template to resolve block documents in
• value_transformer: A function that takes the block placeholder and the block value and returns replacement text for the template

Returns:

• The template with block documents resolved

resolve_variables ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L409" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

resolve_variables(template: T, client: Optional['PrefectClient'] = None) -> T

Resolve variables in a template by replacing each variable placeholder with the value of the variable.

Recursively searches for variable placeholders in dictionaries and lists.

Strips variable placeholders if the variable is not found.

Args:

• template: The template to resolve variables in

Returns:

• The template with variables resolved

Classes

PlaceholderType ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L39" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Placeholder ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/templating/__init__.py#L46" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}