mafw.tools.db_tools

Database Tools

This module provides utility functions for working with database models using the Peewee ORM. It offers helper functions for creating key-value mappings, retrieving primary key information, and combining fields for composite keys or display purposes.

Functions

combine_fields(fields[, join_str])	Combine multiple database fields into a single concatenated string expression.
combine_pk(model[, alias_name, join_str])	Combine primary key fields of a database model into a single aliased field expression.
get_pk(model)	Retrieve the primary key fields of a database model.
make_kv(model, key, value)	Create a key-value mapping from a database model.

mafw.tools.db_tools.combine_fields(fields: list[Field], join_str: str = ' x ') → Function

Combine multiple database fields into a single concatenated string expression.

This function creates an SQL CONCAT expression that combines multiple field values into a single string using the specified separator. It’s particularly useful for creating composite keys or display strings from multiple fields.

Parameters:

• fields (list[peewee.Field]) – List of field objects to be combined.

• join_str (str) – String to use as separator between fields. Defaults to ‘ x ‘.

Returns:

A SQL CONCAT function expression combining the fields.

Return type:

peewee.Function

mafw.tools.db_tools.combine_pk(model: MAFwBaseModel | type[MAFwBaseModel], alias_name: str = 'combo_pk', join_str: str = ' x ') → Alias

Combine primary key fields of a database model into a single aliased field expression.

This function retrieves the primary key fields from the given model using get_pk() and combines them into a single field expression. For models with a single primary key field, it simply aliases that field. For composite primary keys, it uses :func:combine_fields` to concatenate the fields with the specified separator.

Parameters:

• model (MAFwBaseModel | type[MAFwBaseModel]) – The database model or model class to examine for primary key fields.

• alias_name (str) – The alias name to apply to the resulting field expression. Defaults to ‘combo_pk’.

• join_str (str) – String to use as separator between primary key fields when combining. Defaults to ‘ x ‘.

Returns:

An aliased field expression representing the combined primary key.

Return type:

peewee.Alias

mafw.tools.db_tools.get_pk(model: MAFwBaseModel | type[MAFwBaseModel]) → list[Field]

Retrieve the primary key fields of a database model.

This function examines the primary key of the provided model and returns a list of field objects that constitute the primary key. For composite primary keys, it returns all constituent fields; for simple primary keys, it returns a list containing just the primary key field.

Parameters:

model (MAFwBaseModel | type[MAFwBaseModel]) – The database model or model class to examine.

Returns:

A list of field objects representing the primary key fields.

Return type:

list[peewee.Field]

mafw.tools.db_tools.make_kv(model: MAFwBaseModel | type[MAFwBaseModel], key: Field, value: Field) → dict[Any, Any]

Create a key-value mapping from a database model.

This function selects data from a given model using specified key and value fields, and returns a dictionary where keys are values from the key field and values are values from the value field.

Parameters:

• model (MAFwBaseModel | type[MAFwBaseModel]) – The database model or model class to query.

• key (peewee.Field) – The field to use as dictionary keys.

• value (peewee.Field) – The field to use as dictionary values.

Returns:

A dictionary mapping key field values to value field values.

Return type:

dict[Any, Any]

Raises:

AttributeError – If the model parameter doesn’t have the required methods.