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Data source class for populating select parameter options from a database table or query. This class can be imported from the squirrels.data_sources or the squirrels module.

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Constructor

Creates a SelectDataSource object. 
def __init__(
    self, table_or_query: str, id_col: str, options_col: str, 
    *, order_by_col: str | None = None, is_default_col: str | None = None, 
    custom_cols: dict[str, str] = {}, source: SourceEnum = SourceEnum.CONNECTION, 
    user_group_col: str | None = None, parent_id_col: str | None = None, 
    connection: str | None = None
) -> None:

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Examples

A SelectDataSource object is created in the pyconfigs/parameters.py file. It must be created in a function decorated with the create_from_source factory method from SingleSelectParameter or MultiSelectParameter.

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Usage example in parameters.py

from squirrels import parameters as p, data_sources as ds

@p.SingleSelectParameter.create_from_source(
    name="product_category", 
    label="Product Category",
    description="Select a product category"
)
def product_category_source():
    return ds.SelectDataSource(
        table_or_query="""
            SELECT 
                category_id AS id,
                category_name AS name,
                sort_order
            FROM product_categories
        """,
        id_col="id",
        options_col="name",
        order_by_col="sort_order"
    )
In addition, the following are some additional examples for creating a SelectDataSource object.

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Using a table from a specific connection

This example uses a table called “departments” from the “hr_db” connection. 
ds.SelectDataSource(
    table_or_query="departments",
    id_col="dept_id",
    options_col="dept_name",
    connection="hr_db"
)
The connection must either be defined in squirrels.yml or the connections.py file.

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Using seeds as the data source

This example uses a seed file called “status_codes”. 
ds.SelectDataSource(
    table_or_query="status_codes",
    id_col="status_id",
    options_col="status_label",
    source=ds.SourceEnum.SEEDS
)

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Setting default selected options

This example marks certain options as selected by default using a column that contains 1 or 0. 
ds.SelectDataSource(
    table_or_query="""
        SELECT 
            region_id,
            region_name,
            (CASE WHEN is_top_choice = 'y' THEN 1 ELSE 0 END) AS is_default
        FROM regions
    """,
    id_col="region_id",
    options_col="region_name",
    is_default_col="is_default"
)

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Adding custom fields to options

This example creates the following custom fields on each parameter option:
  • code (from column country_code)
  • population (from column population_count)
  • continent (from column continent_name)
ds.SelectDataSource(
    table_or_query="countries",
    id_col="country_id",
    options_col="country_name",
    custom_cols={
        "code": "country_code",
        "population": "population_count",
        "continent": "continent_name"
    }
)

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Enabling cascading effects with a parent parameter

In this example, the available product options are filtered based on the selected value of another parameter called “product_category”. 
@p.SingleSelectParameter.create_from_source(
    name="product", 
    label="Product",
    description="Select a product from the chosen category",
    parent_name="product_category"
)
def product_source():
    return ds.SelectDataSource(
        table_or_query="""
            SELECT 
                product_id,
                product_name,
                category_id,
                price
            FROM products
            ORDER BY product_name
        """,
        id_col="product_id",
        options_col="product_name",
        parent_id_col="category_id"  # Cascades based on category selection
    )