[Idea] Option for applying special formatting to certain columns, e.g., Pretty-printing JSON

[rdlugosz]

Hi - Similar to the concept of smart_columns, or perhaps as an extension of them, how about a way to use a block of Ruby code to format the value of a column when displaying on the page?

The specific use case I have in mind for this is that I've got a result set that includes some JSON in one of the columns. It would be nice if there was a way I could apply some pretty printing (line breaks, indenting, etc) to that value before it's displayed in the table of results.

I suppose this would open up quite a few other options for customization, similar to how you can pass a block to a field in ActiveAdmin and do whatever you'd like with the value before it's displayed (e.g., adding links, styles, etc).

Thanks for considering!

[cianmce]

Something similar to what is done with images could be done here app/helpers/blazer/base_helper.rb#L19
E.g. if it ends in json or yaml then attempt to pretty print and put it in a <pre> tag

Initial attempt in PR: #389