api.graphql

# The second query in a sequence that has arguments arg1, arg2, arg3 gets data for these:
# (i) the arguments explicitly passed to it from the enclosing query (see arguments.graphql)
# (ii) output of the first query as a type, and all the fields of that type
# Here we give example of (ii)

# However, what that means is that you have to define types for intermediate steps.
# Keeping your type system simple means using JSON as the return type of all but the last step.

type Weather {
  temp: Float
}

type Query {
  # Queries `weatherByJSON`,`convertCityOrLocaleToLatLon`, and `weatherByCityOrLocale` use an ecmascript return,
  # which is included in the `@rest` directive.
  # See https://stepzen.com/docs/custom-graphql-directives/directives#ecmascript for more information on `ecmascript`.
  # We are picturing a real-life scenario in which you call a weather API using the `endpoint` argument.
  # See https://stepzen.com/docs/connecting-backends/how-to-connect-a-rest-service for more information on `@rest`.
  weatherByJSON(input: JSON): Weather
    @rest(
      endpoint: "stepzen:empty"
      ecmascript: """
      function transformREST(s) {
          var input = get('input')
          var lat = input['lat']
          var lon = input['lon']
          var temp
          if (lat=='25.76' && lon=='-80.19')
              temp = 100.0
          else
              temp = 60.4
          return (JSON.stringify({"temp":temp}))
      }
      """
    )
  # An ecmascript converter from `cityOrLocale` to its lat/lon.
  # Here, since this will be called first, we declare it to return JSON.
  convertCityOrLocaleToLatLon(cityOrLocale: String): JSON
    @rest(
      endpoint: "stepzen:empty"
      ecmascript: """
      function transformREST(s) {
          var city = get('city')
          if (city == 'Miami')
              return (JSON.stringify({"lat":"25.76","lon":"-80.19"}))
          else
              return (JSON.stringify({"lat":"37.2","lon":"-121.19"}))
      }
      """
    )
  # A `@sequence` directive that sequences `converCityOrLocaleToLatLong` and weather.
  # Now, a cityOrLocale argument can be used to fetch weather data by lat/lon.
  weatherByCityOrLocale(cityOrLocale: String): Weather
    @sequence(
      steps: [
        { query: "convertCityOrLocaleToLatLon" }
        { query: "weatherByJSON" }
      ]
    )
}