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Class for creating date picker parameter widgets that allow users to select a single date. This class can be imported from the squirrels.parameters or the squirrels module.

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Factory methods

Factory methods are class methods that create and configure parameter instances. These methods are typically used in the pyconfigs/parameters.py file to create the parameter configurations (which describes the “shape” of the parameter but does not include the realtime user selections).

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create_simple()

Decorator for creating a simple date parameter that doesn’t involve user attributes or parent parameters. The body of the decorated function does not need to return anything (i.e., it can simply be pass). 
@classmethod
def create_simple(
    cls, name: str, label: str, default_date: str | date, 
    *, description: str = "", min_date: str | date | None = None, 
    max_date: str | date | None = None, date_format: str = '%Y-%m-%d'
) -> Callable:

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create_with_options()

Decorator for creating a parameter with options that can vary based on user attributes or parent parameter selections. The decorated function must return a list of DateParameterOption objects. This is functionally equivalent to create_simple but with additional arguments available for user_attribute and parent_name. 
@classmethod
def create_with_options(
    cls, name: str, label: str, 
    *, description: str = "", user_attribute: str | None = None, 
    parent_name: str | None = None
) -> Callable:

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create_from_source()

Decorator for creating a parameter populated from a database table or query using a DateDataSource. The decorated function must return a DateDataSource object. 
@classmethod
def create_from_source(
    cls, name: str, label: str, 
    *, description: str = "", user_attribute: str | None = None, 
    parent_name: str | None = None
) -> Callable:

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Instance methods

Instance methods are available on parameter instances at query time (in context.py or data models) to retrieve selected values.

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get_selected_date()

Gets the selected date as a string. 
def get_selected_date(self, *, date_format: str | None = None) -> str:
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returns
str
The selected date formatted as a string.

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is_enabled()

Returns True if the parameter has a valid option after applying user attribute and parent parameter selections, False otherwise. 
def is_enabled(self) -> bool:
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returns
bool
True if the parameter has a valid option, False otherwise.

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Examples for factory methods

All examples below are defined in the pyconfigs/parameters.py file.

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Using create_simple for basic date picker

For parameters that only need a single set of constraints, use create_simple. The date parameters are passed directly to the decorator. 
from squirrels import parameters as p
from datetime import date

@p.DateParameter.create_simple(
    name="birth_date", 
    label="Birth Date",
    description="Select your birth date",
    default_date=date(2000, 1, 1),
    min_date=date(1900, 1, 1),
    max_date=date.today()
)
def birth_date_default():
    pass

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Using create_simple with date_format

from squirrels import parameters as p
from datetime import date

@p.DateParameter.create_simple(
    name="birth_date", 
    label="Birth Date",
    description="Select your birth date",
    default_date="01/01/2000",
    min_date="01/01/1900",
    max_date=date.today(),
    date_format="%m/%d/%Y"
)
def birth_date_default():
    pass

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Cascading date parameters

This example shows how date constraints can vary based on a parent parameter selection. 
from squirrels import parameters as p, parameter_options as po
from datetime import date

# Parent parameter
@p.SingleSelectParameter.create_with_options(
    name="fiscal_quarter", 
    label="Fiscal Quarter",
    description="Select fiscal quarter"
)
def fiscal_quarter_options():
    return [
        po.SelectParameterOption(id="2024q1", label="Q1 2024"),
        po.SelectParameterOption(id="2024q2", label="Q2 2024"),
    ]

# Child date parameter with varying constraints
@p.DateParameter.create_with_options(
    name="analysis_date", 
    label="Analysis Date",
    description="Select a date within the chosen quarter",
    parent_name="fiscal_quarter"
)
def analysis_date_options():
    return [
        po.DateParameterOption(
            default_date=date(2024, 1, 15),
            min_date=date(2024, 1, 1),
            max_date=date(2024, 3, 31),
            parent_option_ids="2024q1"
        ),
        po.DateParameterOption(
            default_date=date(2024, 4, 15),
            min_date=date(2024, 4, 1),
            max_date=date(2024, 6, 30),
            parent_option_ids="2024q2"
        ),
    ]

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User-specific date defaults

This example provides different default dates based on user groups. 
from squirrels import parameters as p, parameter_options as po
from datetime import date, timedelta

@p.DateParameter.create_with_options(
    name="access_date", 
    label="Access Date",
    description="Select date to view data",
    user_attribute="access_level"
)
def access_date_options():
    today = date.today()
    return [
        po.DateParameterOption(
            default_date=today,
            min_date=today - timedelta(days=7),
            user_groups=["guest"]  # Guests can only access last 7 days
        ),
        po.DateParameterOption(
            default_date=today,
            min_date=today - timedelta(days=90),
            user_groups=["member"]  # Members can access last 90 days
        ),
        po.DateParameterOption(
            default_date=today,
            min_date=date(2020, 1, 1),
            user_groups=["admin"]  # Admins have full access
        ),
    ]
If custom user fields are defined in pyconfigs/user.py, then they can be used to restrict visibility of parameter options as well. To do so, the user_attribute argument must be prefixed with custom_fields.. 
from squirrels import parameters as p, parameter_options as po
from datetime import date, timedelta

@p.DateParameter.create_with_options(
    name="access_date", 
    label="Access Date",
    description="Select date to view data",
    user_attribute="custom_fields.department"
)
def access_date_options():
    today = date.today()
    return [
        po.DateParameterOption(
            default_date=today,
            user_groups=["sales"]
        ),
        po.DateParameterOption(
            default_date=today - timedelta(days=30),
            min_date=date(2020, 1, 1),
            user_groups=["engineering"]
        ),
    ]

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Date parameter from database source

This example populates date constraints from a database query. 
from squirrels import parameters as p, data_sources as ds

@p.DateParameter.create_from_source(
    name="data_date", 
    label="Data Date",
    description="Select a date with available data"
)
def data_date_source() -> ds.DateDataSource:
    return ds.DateDataSource(
        table_or_query="""
            SELECT 
                MAX(report_date) AS default_date,
                MIN(report_date) AS min_date,
                MAX(report_date) AS max_date
            FROM daily_reports
        """,
        default_date_col="default_date",
        min_date_col="min_date",
        max_date_col="max_date"
    )

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Cascading date from database source

This example shows a date parameter whose constraints come from a database and depend on a parent parameter. 
from squirrels import parameters as p, data_sources as ds

# Parent parameter for projects
@p.SingleSelectParameter.create_from_source(
    name="project", 
    label="Project",
    description="Select a project"
)
def project_source():
    return ds.SelectDataSource(
        table_or_query="projects",
        id_col="project_id",
        options_col="project_name"
    )

# Child date parameter with constraints from database
@p.DateParameter.create_from_source(
    name="project_milestone_date", 
    label="Milestone Date",
    description="Select a milestone date for the project",
    parent_name="project"
)
def project_milestone_date_source():
    return ds.DateDataSource(
        table_or_query="""
            SELECT 
                project_id,
                project_start_date AS min_date,
                project_end_date AS max_date,
                CURRENT_DATE AS default_date
            FROM projects
        """,
        default_date_col="default_date",
        min_date_col="min_date",
        max_date_col="max_date",
        parent_id_col="project_id"
    )

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Examples for instance methods

Once parameters are configured, you can use instance methods in your models to access the selected values. The parameter instances are available through the context object (e.g., sqrl.prms).

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Basic usage in context.py

from squirrels import ContextArgs

def main(ctx: dict[str, Any], sqrl: ContextArgs) -> None:
    if sqrl.param_exists("report_date"):
        report_date_param = sqrl.prms["report_date"]
        assert isinstance(report_date_param, p.DateParameter)
        ctx["selected_date"] = report_date_param.get_selected_date()

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Basic usage in Jinja SQL models

The following example works but is not recommended. See tip below for why. 
-- models/federates/daily_report.sql
SELECT *
FROM sales
WHERE sale_date = {{ prms["report_date"].get_selected_date() | quote }}
It is generally better to only use the instance methods in context.py to transform parameter selections into context variables. Using the instance methods directly in the data models is not recommended.IDEs can provide code suggestions for the available instance methods in Python instead of having to memorize which method (such as get_selected_date) is available to use for DateParameter objects.

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Using custom date formats

# In context.py
def main(ctx: dict[str, Any], sqrl: ContextArgs) -> None:
    if sqrl.param_exists("event_date"):
        event_date_param = sqrl.prms["event_date"]
        assert isinstance(event_date_param, p.DateParameter)

        ctx["formatted_date"] = event_date_param.get_selected_date(date_format="%B %d, %Y")
        ctx["month_year"] = event_date_param.get_selected_date(date_format="%Y-%m")