gatsby-pingbot/lib/schema.ts

import { model, models, Schema } from "mongoose"

interface URL {
  url: string
}

const schema = new Schema<URL>({
  url: {
    type: String,
    required: true,
    unique: true
  }
})

schema.path('url').validate(async function(value) {
  const count = await models.URL.countDocuments({ url: value })

  return !count
}, 'URL already exists')

const URLModel = model<URL>('url', schema)

export = URLModel