[help] how to dynamically create a parameterized report file name with tar_render()

[brndngrhm]

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Description

I have a workflow where i fit 2 models for different customer types and then assess the models using tar_render() to create an HTML report. I am using branching and when i create the assessment reports i want to make sure to add the customer type to the report filename to distinguish the html outputs. However i am getting the following error when i try to pass customer_type to output_file:

Failed to evaluate glue component {customer_type}
Caused by error:
! object 'customer_type' not found

below is a simplified example of my pipeline:

  list(
    tar_target(
        name = analysis_data,
        make_analysis_data(data)
      ),
    tar_target(
        customer_type,
        c("US", "Intl"),
      ),
    tar_target(
        name = UMAP,
        train_umap(analysis_data, customer_type= customer_type),
        pattern = map(customer_type),
        deployment = "worker"
      ),
    # Target to render the UMAP assessment report
    tar_target(
      name = assess_UMAP,
      {
        # Dynamically construct the output file name
         output_file <- glue::glue("assess-UMAP-{customer_type}.html")
        
        # Render the report with tar_render
        tar_render(
          path = "R/reports/assess-UMAP.qmd",
          params = list(
            analysis_data_param = analysis_data,
            customer_type_param = customer_type,
            model_path_param = UMAP
          ),
          output_file = output_file,
          output_dir = output_dir, # defined in _targets.R
        )
      },
      pattern = map(customer_type, UMAP),
      format = "file"
    )
)

[wlandau]

tar_render() is itself a target, so nesting it inside tar_target() is probably not what you're going for. In your case, I would do something like:

library(targets)
list(
  tar_target(
    name = analysis_data,
    make_analysis_data(data)
  ),
  tar_target(
    customer_type,
    c("US", "Intl"),
  ),
  tar_target(
    name = UMAP,
    train_umap(analysis_data, customer_type= customer_type),
    pattern = map(customer_type),
    deployment = "worker"
  ),
  tar_target(
    name = report_file,
    command = "R/reports/assess-UMAP.qmd",
    format = "file"
  ),
  tar_target(
    name = assess_UMAP,
    command = {
      rmarkdown::render(report_file, ...)
      WRITE_OUTPUT_FILE_HERE
    },
    pattern = map(customer_type, UMAP),
    format = "file"
  )
)

[brndngrhm]

thank you! that worked, i was able to dynamically create report titles