Dummy

Module for the DummyWriter class.

koheesio.spark.writers.dummy.DummyWriter

A simple DummyWriter that performs the equivalent of a df.show() on the given DataFrame and returns the first row of data as a dict.

This Writer does not actually write anything to a source/destination, but is useful for debugging or testing purposes.

Parameters:

Name	Type	Description	Default
n	PositiveInt	Number of rows to show.	20
truncate	bool | PositiveInt	If set to True, truncate strings longer than 20 chars by default. If set to a number greater than one, truncates long strings to length truncate and align cells right.	True
vertical	bool	If set to True, print output rows vertically (one line per column value).	False

n class-attribute instance-attribute

n: PositiveInt = Field(
    default=20, description="Number of rows to show.", gt=0
)

truncate class-attribute instance-attribute

truncate: Union[bool, PositiveInt] = Field(
    default=True,
    description="If set to ``True``, truncate strings longer than 20 chars by default.If set to a number greater than one, truncates long strings to length ``truncate`` and align cells right.",
)

vertical class-attribute instance-attribute

vertical: bool = Field(
    default=False,
    description="If set to ``True``, print output rows vertically (one line per column value).",
)

Output

DummyWriter output

df_content class-attribute instance-attribute

df_content: str = Field(
    default=...,
    description="The content of the DataFrame as a string",
)

head class-attribute instance-attribute

head: Dict[str, Any] = Field(
    default=...,
    description="The first row of the DataFrame as a dict",
)

execute

execute() -> Output

Execute the DummyWriter

Source code in src/koheesio/spark/writers/dummy.py

def execute(self) -> Output:
    """Execute the DummyWriter"""
    # logs the equivalent of doing df.show()
    df_content = show_string(df=self.df, n=self.n, truncate=self.truncate, vertical=self.vertical)
    self.log.info(f"content of df that was passed to DummyWriter:\n{df_content}")

    self.output.head = self.df.head().asDict()
    self.output.df_content = df_content

int_truncate

int_truncate(truncate_value: Union[int, bool]) -> int

Truncate is either a bool or an int.

Parameters:

truncate_value : int | bool, optional, default=True If int, specifies the maximum length of the string. If bool and True, defaults to a maximum length of 20 characters.

Returns:

int The maximum length of the string.

Source code in src/koheesio/spark/writers/dummy.py

@field_validator("truncate")
def int_truncate(cls, truncate_value: Union[int, bool]) -> int:
    """
    Truncate is either a bool or an int.

    Parameters:
    -----------
    truncate_value : int | bool, optional, default=True
        If int, specifies the maximum length of the string.
        If bool and True, defaults to a maximum length of 20 characters.

    Returns:
    --------
    int
        The maximum length of the string.

    """
    # Same logic as what is inside DataFrame.show()
    if isinstance(truncate_value, bool) and truncate_value is True:
        return 20  # default is 20 chars
    return int(truncate_value)  # otherwise 0, or whatever the user specified