Support params argument in aql.render to declare values to SQL Jinja template #125

[dimberman]

Context
At the moment, Astro 0.5.1 does not use the params keyword argument. This argument would allow us to overwrite SQL Jinja template values.

Example:

SELECT
   t.table_schema,
   t.table_name,
   CONCAT(t.table_catalog, '.', t.table_schema, '.', t.table_name) table_path
FROM dwh_legacy.information_schema.tables t
WHERE
       t.table_schema IN ({{ params.schemas }})
   AND t.table_type = 'BASE TABLE';

aql.render(path='/usr/local/airflow/include/sql/schemas',
                                      params={'schemas': dwh_schemas})

Currently raises the error:

  File "/sr/local/lib/python3.9/site-packages/jinja2/runtime.py", line 903, in _fail_with_undefined_error
      raise self._undefined_exception(self._undefined_message)
jinja2.exceptions.UndefinedError: 'dict object' has no attribute 'schemas'

Acceptance criteria

• Users of aql.render can override Jinja template values by using the params argument
• Have an example_dag which uses params
• Add at least one unit test which validate this behaviour
• Update the docstring so it details this feature
• Ask @mag3141592 (bug reporter) to review the PR

This PR addresses one part of the previous PR that was not correctly implemented, namely the adding params at a task level as well as at the DAG level

addresses #125

[codecov]

Codecov Report

Merging #254 (2ee62e3) into main (23cab8b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #254   +/-   ##
=======================================
  Coverage   90.82%   90.83%           
=======================================
  Files          36       36           
  Lines        1526     1527    +1     
  Branches      256      257    +1     
=======================================
+ Hits         1386     1387    +1     
  Misses        114      114           
  Partials       26       26           

Impacted Files	Coverage Δ
src/astro/sql/parsers/sql_directory_parser.py	92.03% <100.00%> (+0.07%)	⬆️

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[kaxil]

Please add a separate unit test (or add to an existing test) to check that using {{ params.col }} produces room

[kaxil]

Cool, only 1 item remaining - #254 (comment)