Support outputting a list of databases as JSON

[kate-goldenring]

Takes a similar approach as spin templates list and provides an option of listing databases as JSON

Example output:

[
  {
    "database": "brilliant-kangaroo",
    "links": [
      {
        "label": "default",
        "app": "todo"
      }
    ]
  },
  {
    "database": "mydb",
    "links": [
      {
        "label": "hello",
        "app": "todo"
      },
      {
        "label": "foo",
        "app": "bar"
      }
    ]
  }
]

[kate-goldenring]

@itowlson I noticed that in spin templates list, we hide the optionality of json output format. Is there a reason for that -- and one that is related to whether it should be hidden here too?

[itowlson]

@kate-goldenring Just to reduce clutter in the help text. In that case, the JSON is primarily expected to be consumed by other programs, not be interactive users, so I felt it was not worth making interactive users look at the flag.

[itowlson]

Looks good (style nit aside) but I think it needs to either respect the --app filter or (less desirably) be incompatible with it.

[itowlson]

🎉 Looks good!

[rylev]

Seems fine though there does seem to be unnecessary code duplication between the json and table formatting code paths.

[rylev]

Seems we're repeating a lot of the same logic here between json and table printing. Why not delay the formatting decision until we've munged all the data?

[kate-goldenring]

One is iterating over Links while the other is over Databases since the tabular form does one row per link while the json form does one array entry per database. If we want to do links as teh output format for json, we could share code but i think it makes more sense in json to represent a database and then nest all its links