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Context File

The context file (pyconfigs/context.py) is where you can process runtime inputs, such as (but not limited to) parameter selections, into meaningful variables that can be used in the data models. The file contains a single main function with the arguments ctx and sqrl.

  • ctx (short for "context) is the output dictionary that is written to in the function. The keys should be strings, and the values can be anything.
  • sqrl is an object of type ContextArgs that contains inputs/utilities you may choose to use. Some examples include:
    • The sqrl.prms attribute, a dictionary for parameter names to the associated Parameter object.
    • The sqrl.user attribute, the authorized user if authenticated else None. The attributes for the user can be defined in the User model in pyconfigs/auth.py (more details can be found at Authentication).
    • The sqrl.traits attributes, a dictionary of the dataset traits (defined in squirrels.yml) for the running dataset

This file is run for every dataset request, and this same file is used for all datasets. Thus, it is important to use if statements to avoid running blocks of code that don't apply to the situation (for instance, context variables for parameters that don't exist for the dataset).

Although it is often possible to define variables similarly in Jinja (with reusable macros), IDEs tend to have better support for providing auto-fill suggestions in Python than in Jinja. Not to mention, there are many situations where it's much easier to process variables in Python than in Jinja.

The following is a sample main function in the "context.py" file.

def main(ctx: dict[str, Any], sqrl: sr.ContextArgs) -> None:
    if "group_by" in sqrl.prms:
        group_by_param: sr.MultiSelectParameter = sqrl.prms["group_by"]
        dimension_columns: list[str] = group_by_param.get_selected("columns")
        ctx["group_by_cols"] = ",".join(dimension_columns)
tip

If you wish to use some custom Python function in Jinja, it's possible to do so by setting a context variable to the function!

In context.py:

def my_func(args):
    ...

ctx["my_function"] = my_func

In Jinja:

{%- set my_func = ctx["my_function"] -%}

{{ my_func("some_args") }}