Implement download data dictionary functionality

[rmanaem]

Now that the user can upload a data table and add/edit the description they should be able to download the result of their hard work and of course the downloaded data dictionary should have their latest description.

[rmanaem]

@neurobagel/dev Could someone please drop an example of what we expect the output data dictionary to look like in the new tool? Given we're also including information in the BIDS section.

[alyssadai]

I think our existing reference example annotated data dictionary https://github.com/neurobagel/neurobagel_examples/blob/main/data-upload/example_synthetic.json pretty much includes accurate (i.e., to be kept the same) examples of all the different BIDS sections we would encounter (everything not under the "Annotations" key per column), with the exception of the age column.

AFAICT the age column pheno_age in the example data dictionary is missing two things that the new annotation tool will support:

1. "Units" in the BIDS section (you can find also a pure BIDS example here)
2. "Transformation" will now be named "Format"

So, instead of:

...
    "pheno_age": {
        "Description": "Age of the participant",
        "Annotations": {
            "IsAbout": {
                "TermURL": "nb:Age",
                "Label": "Age"
            },
            "Transformation": {
                "TermURL": "nb:FromEuro",
                "Label": "european decimal value"
            },
            "MissingValues": [
                "NA"
            ]
        }
    },
...

(from the current example file)

it would be (assuming the user completes all the optional steps during annotation)

...
    "pheno_age": {
        "Description": "Age of the participant",
        "Units": "years",
        "Annotations": {
            "IsAbout": {
                "TermURL": "nb:Age",
                "Label": "Age"
            },
            "Format": {
                "TermURL": "nb:FromEuro",
                "Label": "european decimal value"
            },
            "MissingValues": [
                "NA"
            ]
        }
    },
...

@surchs, let me know if that sounds right to you / if I'm missing anything!

[alyssadai]

Oh, just a had a thought: we are planning to introduce a new annotation for nb:SubjectGroup (healthy control will be one of these), so this would also be an addition to our existing example.

We haven't discussed the implementation in detail, but I suspect it will look something like this:

    "Annotations": {
      "IsAbout": {
        "TermURL": "nb:SubjectGroup",
        "Label": "Study group for subject"
      },
      "Levels": {
        "CTRL": {
          "TermURL": "ncit:C94342",
          "Label": "Healthy Control"
        }
      }

@surchs, does that make sense to you?