Potential issue with index_date not updating in dummy data

[alschaffer]

I am extracting data on people prescribed an opioid in each month (see example code below). When extracting dummy data, the index_date doesn't update, it only takes on the initial value (i.e. the match date variable only results in dates from the first month of the series [2018-01-01], not subsequent months). Note that --index-date-range "2018-01-01 to 2022-03-01 by month" is specified in the project.yaml. We have confirmed that this doesn't happen with real data, it appears to only be an issue when creating dummy data.

More details are available in this Slack thread: https://bennettoxford.slack.com/archives/C33TWNQ1J/p1660747406136349

opioid_any = patients.with_these_medications(
    opioid_codes,
    between = ["first_day_of_month(index_date)", "last_day_of_month(index_date)"],
    returning = "binary_flag",
    find_first_match_in_period = True,
    include_date_of_match = True,
    date_format = "YYYY-MM-DD",
    return_expectations= {
      "date": {
        "earliest": "first_day_of_month(index_date)",
        "latest": "last_day_of_month(index_date)",
        },
      "incidence": 0.15
      },
  ),

  generate_cohort:
    run: >
      cohortextractor:latest generate_cohort
        --study-definition study_definition
        --index-date-range "2018-01-01 to 2022-03-01 by month"
        --output-dir=output
    outputs:
      highly_sensitive:
        cohort: output/input_*.csv