bcherny
$merge in schema produces empty typescript interface
I have a json schema using keyword $merge (to merge two subschemas, where allof fails due to the 'additionalProperties=false' issue). Passing it through the json-schema-to-typescript gives an empty interface.
Is $merge part of the JSON-Schema spec, or is it a custom extension you're using?
I just came across this issue looking to see if json-schema-to-typescript supports $merge and $patch.
I'm only learning this stuff as I go, but maybe if I add in my senario it'll help with context.
The base JSON-Schema spec doesn't have strong support for extending/inheriting schemas. This can make it difficult to write complex schemas without a lot of copy-paste or undesirable behaviours^. Instead there are are two additional specifications to help express schemas in a DRY way $extend and $merge.
As they are seperate specifications some tools choose to support them but via an optional add-on. ajv for example has ajv-merge-patch.
RFC: JavaScript Object Notation (JSON) Patch RFC: JSON Merge Patch
So I believe the answer is yes it's a "custom extension", but it is a somewhat standard extension.
As I said I'm learning this stuff now so I could be wrong, but I hope that helps. I was investigating using $extend in my work to improve the generated types/schemas, but I'm not sure if it's ideal.
^I'm seeing undesirable behaviour when I use allOf and $ref syntax, the tools are working as intended but I'm not getting the ideal end result, which lead me to $extend.
Shoot, just bumped into the same issue, using $merge for my schemas and trying to generate TS from it.
I'd settle for a way to generate a 'normal' schema from one that has '$merge' in it, I'm also learning, did you find a way in the mean time @jaredhope?
If someone wants to take this on, a good start would be speccing out how exactly $merge differs from allOf. If the two are identical, this could simply be implemented as a normalizer rules that transforms $merge to allOf.