> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pysquirrels.com/llms.txt
> Use this file to discover all available pages before exploring further.

# NumberParameter

> Numeric input parameter

Class for creating numeric input parameter widgets that allow users to enter a single numeric value.

This class can be imported from the `squirrels.parameters` or the `squirrels` module.

## 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).

### create\_simple()

Decorator for creating a simple numeric 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`).

```python theme={null}
@classmethod
def create_simple(
    cls, name: str, label: str, min_value: decimal.Decimal | int | float | str, 
    max_value: decimal.Decimal | int | float | str,
    *, description: str = "", increment: decimal.Decimal | int | float | str = 1, 
    default_value: decimal.Decimal | int | float | str | None = None
) -> Callable:
```

<Expandable title="arguments" defaultOpen>
  <ResponseField name="name" type="str" required>
    The unique identifier for this parameter. Used to reference the parameter at query time (such as in `context.py` or when specifying parameter selections in the APIs).
  </ResponseField>

  <ResponseField name="label" type="str" required>
    The display label shown to users in the UI.
  </ResponseField>

  <ResponseField name="min_value" type="decimal.Decimal | int | float | str" required>
    Minimum selectable value. Must be less than or equal to `max_value`.
  </ResponseField>

  <ResponseField name="max_value" type="decimal.Decimal | int | float | str" required>
    Maximum selectable value. Must be greater than or equal to `min_value`.
  </ResponseField>

  <ResponseField name="description" type="str" default="">
    An optional description explaining the purpose of this parameter.
  </ResponseField>

  <ResponseField name="increment" type="decimal.Decimal | int | float | str" default="1">
    Increment of selectable values. Must fit evenly between `min_value` and `max_value`.
  </ResponseField>

  <ResponseField name="default_value" type="decimal.Decimal | int | float | str | None" default="None">
    Default value for this parameter. Must be selectable based on `min_value`, `max_value`, and `increment`. If None, defaults to `min_value`.
  </ResponseField>
</Expandable>

### 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 [NumberParameterOption](/references/python/parameter_options/numberparameteroption) objects.

```python theme={null}
@classmethod
def create_with_options(
    cls, name: str, label: str, 
    *, description: str = "", user_attribute: str | None = None, 
    parent_name: str | None = None
) -> Callable:
```

<Expandable title="arguments" defaultOpen>
  <ResponseField name="name" type="str" required>
    The unique identifier for this parameter. Used to reference the parameter at query time (such as in `context.py` or when specifying parameter selections in the APIs).
  </ResponseField>

  <ResponseField name="label" type="str" required>
    The display label shown to users in the UI.
  </ResponseField>

  <ResponseField name="description" type="str" default="">
    An optional description explaining the purpose of this parameter.
  </ResponseField>

  <ResponseField name="user_attribute" type="str | None" default="None">
    A user attribute (like "access\_level") that determines which options are visible to different users. The decorated function should return options with matching `user_groups` values.

    To use custom user fields defined in `pyconfigs/user.py`, prefix with `custom_fields.` (e.g., `"custom_fields.department"`).
  </ResponseField>

  <ResponseField name="parent_name" type="str | None" default="None">
    The name of a parent parameter that controls which options are visible. The decorated function should return options with `parent_option_ids` matching the parent's selected value.
  </ResponseField>
</Expandable>

### create\_from\_source()

Decorator for creating a parameter populated from a database table or query using a [NumberDataSource](/references/python/data_sources/numberdatasource).

The decorated function must return a [NumberDataSource](/references/python/data_sources/numberdatasource) object.

```python theme={null}
@classmethod
def create_from_source(
    cls, name: str, label: str, 
    *, description: str = "", user_attribute: str | None = None, 
    parent_name: str | None = None
) -> Callable:
```

<Expandable title="arguments" defaultOpen>
  <ResponseField name="name" type="str" required>
    The unique identifier for this parameter. Used to reference the parameter at query time (such as in `context.py` or when specifying parameter selections in the APIs).
  </ResponseField>

  <ResponseField name="label" type="str" required>
    The display label shown to users in the UI.
  </ResponseField>

  <ResponseField name="description" type="str" default="">
    An optional description explaining the purpose of this parameter.
  </ResponseField>

  <ResponseField name="user_attribute" type="str | None" default="None">
    A user attribute that determines which options from the data source are visible to different users.

    To use custom user fields defined in `pyconfigs/user.py`, prefix with `custom_fields.`.
  </ResponseField>

  <ResponseField name="parent_name" type="str | None" default="None">
    The name of a parent parameter that controls which options from the data source are visible.
  </ResponseField>
</Expandable>

## Instance methods

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

### get\_selected\_value()

Gets the selected numeric value as a float.

```python theme={null}
def get_selected_value(self) -> float:
```

<ResponseField name="returns" type="float">
  The selected numeric value converted from Decimal to float.
</ResponseField>

### is\_enabled()

Returns True if the parameter has a valid option after applying user attribute and parent parameter selections, False otherwise.

```python theme={null}
def is_enabled(self) -> bool:
```

<ResponseField name="returns" type="bool">
  True if the parameter has a valid option, False otherwise.
</ResponseField>

## Examples for factory methods

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

### Using create\_simple for basic numeric input

For parameters that only need a single set of constraints, use `create_simple`. The numeric parameters are passed directly to the decorator.

```python highlight="3" theme={null}
from squirrels import parameters as p

@p.NumberParameter.create_simple(
    name="threshold", 
    label="Threshold Value",
    min_value=0,
    max_value=1000,
    increment=10,
    default_value=100,
    description="Enter threshold value"
)
def threshold_default():
    pass
```

### Number parameter with decimal precision

This example uses decimal values for precise numeric input. Regardless of whether `Decimal`, float, or string values are used, the exact precision will always be maintained (without floating point errors).

```python highlight="7-10" theme={null}
from squirrels import parameters as p
from decimal import Decimal

@p.NumberParameter.create_simple(
    name="price_multiplier", 
    label="Price Multiplier",
    min_value="0.1",
    max_value="2.0",
    increment=0.1,
    default_value=Decimal("1.2"),
    description="Enter price multiplier (0.1 to 2.0)"
)
def price_multiplier_default():
    pass
```

### Cascading number parameters

This example shows how numeric constraints can vary based on a parent parameter selection.

```python highlight="20,29,36" theme={null}
from squirrels import parameters as p, parameter_options as po

# Parent parameter
@p.SingleSelectParameter.create_with_options(
    name="product_type", 
    label="Product Type",
    description="Select product type"
)
def product_type_options():
    return [
        po.SelectParameterOption(id="small", label="Small Items"),
        po.SelectParameterOption(id="large", label="Large Items"),
    ]

# Child number parameter with varying constraints
@p.NumberParameter.create_with_options(
    name="order_quantity", 
    label="Order Quantity",
    description="Enter quantity based on product type",
    parent_name="product_type"
)
def order_quantity_options():
    return [
        po.NumberParameterOption(
            default_value=10,
            min_value=1,
            max_value=100,
            increment=1,
            parent_option_ids="small"
        ),
        po.NumberParameterOption(
            default_value=5,
            min_value=1,
            max_value=20,
            increment=1,
            parent_option_ids="large"
        ),
    ]
```

### User-specific numeric constraints

This example provides different numeric constraints based on user access levels.

```python highlight="7,16,23" theme={null}
from squirrels import parameters as p, parameter_options as po

@p.NumberParameter.create_with_options(
    name="budget_limit", 
    label="Budget Limit",
    description="Set budget limit based on your access level",
    user_attribute="access_level"
)
def budget_limit_options():
    return [
        po.NumberParameterOption(
            default_value=1000,
            min_value=0,
            max_value=5000,
            increment=100,
            user_groups=["member", "guest"]
        ),
        po.NumberParameterOption(
            default_value=5000,
            min_value=0,
            max_value=50000,
            increment=1000,
            user_groups=["admin"]
        ),
    ]
```

### Number parameter from database source

This example populates numeric constraints from a database query.

```python highlight="3,8" theme={null}
from squirrels import parameters as p, data_sources as ds

@p.NumberParameter.create_from_source(
    name="inventory_quantity", 
    label="Inventory Quantity",
    description="Enter quantity (based on current inventory)"
)
def inventory_quantity_source() -> ds.NumberDataSource:
    return ds.NumberDataSource(
        table_or_query="""
            SELECT 
                AVG(quantity) AS default_value,
                MIN(quantity) AS min_value,
                MAX(quantity) AS max_value,
                1 AS increment
            FROM inventory
        """,
        default_value_col="default_value",
        min_value_col="min_value",
        max_value_col="max_value",
        increment_col="increment"
    )
```

### Cascading number from database source

This example shows a number parameter whose constraints come from a database and depend on a parent parameter.

```python highlight="20,37" theme={null}
from squirrels import parameters as p, data_sources as ds

# Parent parameter for projects
@p.SingleSelectParameter.create_from_source(
    name="department_id", 
    label="Department",
    description="Select a department"
)
def department_source():
    return ds.SelectDataSource(
        table_or_query="departments",
        id_col="department_id",
        options_col="department_name"
    )

@p.NumberParameter.create_from_source(
    name="allocation_amount", 
    label="Allocation Amount",
    description="Enter allocation amount for the selected department",
    parent_name="department_id"
)
def allocation_amount_source():
    return ds.NumberDataSource(
        table_or_query="""
            SELECT 
                department_id,
                budget_default AS default_value,
                budget_min AS min_value,
                budget_max AS max_value,
                100 AS increment
            FROM department_budgets
        """,
        default_value_col="default_value",
        min_value_col="min_value",
        max_value_col="max_value",
        increment_col="increment",
        parent_id_col="department_id"
    )
```

## 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`).

### Basic usage in context.py

```python highlight="7" theme={null}
from squirrels import ContextArgs

def main(ctx: dict[str, Any], sqrl: ContextArgs) -> None:
    if sqrl.param_exists("threshold"):
        threshold_param = sqrl.prms["threshold"]
        assert isinstance(threshold_param, p.NumberParameter)
        ctx["threshold_value"] = threshold_param.get_selected_value()
```

### Basic usage in Jinja SQL models

The following example works but is not recommended. See tip below for why.

```sql highlight="4" theme={null}
-- models/federates/filtered_data.sql
SELECT *
FROM products
WHERE price >= {{ prms["threshold"].get_selected_value() }}
```

<Tip>
  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_value`) is available to use for `NumberParameter` objects.
</Tip>

### Using numeric values in calculations

```python highlight="7-9" theme={null}
# In context.py
def main(ctx: dict[str, Any], sqrl: ContextArgs) -> None:
    if sqrl.param_exists("price_multiplier"):
        multiplier_param = sqrl.prms["price_multiplier"]
        assert isinstance(multiplier_param, p.NumberParameter)
        
        multiplier = multiplier_param.get_selected_value()
        ctx["adjusted_price"] = 100 * multiplier
        ctx["discount_percentage"] = (1 - multiplier) * 100
```