lakehouse_files_writer

sqllocks_spindle.fabric.lakehouse_files_writer

Lakehouse Files landing-zone writer for Fabric.

Classes

LakehouseWriteResult dataclass

Result of a Lakehouse write_all() operation.

LakehouseFilesWriter

Write data files into Lakehouse Files landing zones.

This writer targets the Files/ area of a Fabric Lakehouse (flat files in landing zones), as opposed to :class:~sqllocks_spindle.output.DeltaWriter which writes Delta tables into the Tables/ area.

Uses :class:OneLakePaths for consistent path construction and works both inside a Fabric runtime and locally with a configurable base path.

Parameters:

Name	Type	Description	Default
base_path	str | Path | None	Root path for the Lakehouse Files area. Passed through to :class:OneLakePaths. If None, auto-detects Fabric or falls back to ./lakehouse_files.	None
default_format	str	Default output format — "parquet", "csv", or "jsonl" (default "parquet").	'parquet'

Example::

from sqllocks_spindle.fabric import LakehouseFilesWriter, OneLakePaths

writer = LakehouseFilesWriter(base_path="./test_output")
paths = OneLakePaths(base_path="./test_output")
dest = paths.landing_zone_path("retail", "order", "2025-01-15", hour=10)

writer.write_partition(df, dest, format="parquet")
writer.write_done_flag(paths.done_flag_path("retail", "order", "2025-01-15"))

Attributes

paths property

Return the underlying :class:OneLakePaths instance.

Methods:

write_all(tables, format=None, **kwargs)

Write each table as a bulk file (Parquet/CSV/JSONL).

Conforms to the SpindleWriter protocol so LakehouseFilesWriter can be used with MultiWriter.

Parameters:

Name	Type	Description	Default
tables	dict[str, DataFrame]	Mapping of table_name -> DataFrame.	required
format	str | None	Output format (defaults to writer's default_format).	None
**kwargs	Any	Extra args passed to write_partition.	{}

Returns:

Type	Description
LakehouseWriteResult	LakehouseWriteResult with per-table row counts and any errors.

write_partition(df, path, format=None, file_naming_template=None)

Write a DataFrame as a data file into a landing-zone partition.

Parameters:

Name	Type	Description	Default
df	DataFrame	DataFrame to write.	required
path	str | Path	Target directory for the partition.	required
format	str | None	Output format — "csv", "parquet", or "jsonl". Falls back to default_format if None.	None
file_naming_template	str | None	Template for the output file name. Supports {format} placeholder. Defaults to "part-0001.{format}".	None

Returns:

Type	Description
Path	Path to the written file.

Raises:

Type	Description
ValueError	If format is unsupported.

write_manifest(manifest_dict, path)

Write a manifest JSON file to the control directory.

Parameters:

Name	Type	Description	Default
manifest_dict	dict[str, Any]	Manifest contents (serialised as JSON).	required
path	str | Path	Full path to the manifest file.	required

Returns:

Type	Description
Path	Path to the written manifest file.

write_done_flag(path)

Write an empty _SUCCESS sentinel file.

Parameters:

Name	Type	Description	Default
path	str | Path	Full path to the done-flag file.	required

Returns:

Type	Description
Path	Path to the written sentinel file.