Fastify - TypeError: Cannot read property 'length' of undefined

Question

When i created a new API with fastify, while testing it, it was throwing

TypeError: Cannot read property 'length' of undefined

      at next (node_modules/fastify/lib/route.js:407:32)
      at preParsingHookRunner (node_modules/fastify/lib/route.js:438:3)
      at runPreParsing (node_modules/fastify/lib/route.js:389:5)
      at Object.routeHandler [as handler] (node_modules/fastify/lib/route.js:349:7)
      at Router.lookup (node_modules/find-my-way/index.js:356:14)

The control doesn't even pass to the routes and when i checked the file mentioned in the stack trace, it seems to be related with preParser

Answer 1

It was apparently a JSON Schema issue.

In one of the routes, I had the schema like this,

{
  type: "object",
  required: ["fileType"],
  properties: {
    fileType: {
      type: {
         type: "string",
         enum: ["a", "b", "c", "d", "all"]
      }
    }
  }
}

Which is wrong, and it should be,

{
  type: "object",
  required: ["fileType"],
  properties: {
    fileType: {
      type: "string",
      enum: ["a", "b", "c", "d", "all"]
    }
  }
}