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Function Resolver

name​

Type​

string!

Values​

function:run

options​

The options object contains configuration specific to the type of resolver you select.

args​

Type​

ParameterConfig?

Description​

Allows mapping from the QueryContext to the args values (input arguments) for the resolver. Results are not serialized. For more information read about the ParameterConfig.

results​

Type​

ParameterConfig?

Description​

Allows mapping from the QueryContext to the results for the resolver step in a ComposeResolver or whole query. Results are not serialized. For more information read about the ParameterConfig.

javascript​

Type​

string!

Description​

Allows writing arbitrary Javascript code with access to the FunctionResolverContext.

Your code can either be written "inline", e.g., ({sum: 1 + 1}) or as a valid ESM, e.g., export default function() { return {sum: 1 + 1}; }.

For inline code the FunctionResolverContext is present as globals, e.g., ({sum: $args.input + 42}), while for ESM code the context is exposed as the args object to the entrypoint function, e.g., export default function({$args}) { return {sum: $args.input + 42}; }.

Imports​

When writing ESM code you can use remote imports, similar to what you'd use in a browser. For example, the code below will make use of the htmlparser2 library.

import {parseDocument} from 'https://esm.sh/htmlparser2@9.1.0';

export default function({$args}) {
  return parseDocument(\\`<span>hello \${$args.input}</span>\\`).firstChild.firstChild.data;
}

System-Cached Imports​

A few libraries are cached and can be imported without a network request. Note that the import URL must match this URL exactly to take advantage of the system-cached library imports.

If you would like to see additional libraries cached, please open a support request.

warning

Because non-cached imports can have a significant and unpredictable impact on performance, we recommend only using system-cached imports in production.

Javascript Function Example​

{
  "getScore": {
    "resolver": {
      "compose": [
        {
          "id": "first",
          "name": "util:noop",
          "value": {
            "value": 1
          }
        },
        {
          "id": "second",
          "name": "util:noop",
          "value": {
            "value": 2
          }
        },
        {
          "name": "function:run",
          "javascript": "// see below"
        }
      ]
    },
    "args": {
      "type": "object",
      "properties": {
        "name": { "type": "string" }
      }
    },
    "shape": "Score"
  },
  "shapes": {
    "Score": {
      "name": "Score",
      "title": "Score",
      "schema": {
        "type": "object",
        "properties": {
          "score": {
            "type": "string"
          }
        }
      }
    }
  }
}
export default function ({ $args, $results, $resultsById, $resultsByIndex }) {
  const { name } = $args;
  const sum = $resultsById.second.value + $resultsByIndex[0].value + $results.value;
  return { score: `${name}: ${sum}` };
}
{
  getScore(name: 'Beagles') {score}
}
{
  "data": {
    "getScore": { "score": "Beagles: 5" }
  }
}

Schema Example​

Using https://api.weather.gov/gridpoints/OKX/36,34/forecast as a data source.

{
  "properties": {
    "units": "us",
    "forecastGenerator": "BaselineForecastGenerator",
    "generatedAt": "2024-07-02T17:33:30+00:00",
    "updateTime": "2024-07-02T16:32:21+00:00",
    "validTimes": "2024-07-02T10:00:00+00:00/P7DT3H",
    "elevation": {
      "unitCode": "wmoUnit:m",
      "value": 18.897600000000001
    },
    "periods": [
      {
        "number": 1,
        "name": "This Afternoon",
        "startTime": "2024-07-02T13:00:00-04:00",
        "endTime": "2024-07-02T18:00:00-04:00",
        "isDaytime": true,
        "temperature": 84,
        "temperatureUnit": "F",
        "temperatureTrend": "",
        "probabilityOfPrecipitation": {
          "unitCode": "wmoUnit:percent",
          "value": null
        },
        "windSpeed": "5 to 9 mph",
        "windDirection": "SE",
        "icon": "/icons/land/day/few?size=medium",
        "shortForecast": "Sunny",
        "detailedForecast": "Sunny. High near 84, with temperatures falling to around 80 in the afternoon. Southeast wind 5 to 9 mph."
      }
    ]
  }
}
{
  "getForecast": {
    "resolver": {
      "compose": [
        {
          "id": "weather",
          "name": "rest:get",
          "service": "weather",
          "path": "/gridpoints/OKX/36,34/forecast"
        },
        {
          "name": "function:run",
          "javascript": "export default function handler({ $resultsById }) { const period = $resultsById.weather.properties.periods[0]; return `${period.name} will be ${period.temperature}${period.temperatureUnit}.`}"
        }
      ]
    }
  }
}
query {
  getForecast
}
{
  "data": {
    "getForecast": "This Afternoon will be 84F."
  }
}

Function Resolver Context​

A special context available to the function resolver. Contains the follow properties.

$args​

See the definition

$claims​

See the definition

$source​

See the definition

$request​

See the definition

$resolver​

Type​

FunctionResolver!

Description​

The resolver config that is running this function.

$first​

Type​

any!

Description​

The results of the first resolver to execute.

$results​

Type​

any!

Description​

The results of the last (most recent or previous) resolver to execute.

$resultsById​

Type​

Record<string, any>!

Description​

The results of a resolver by the provided id.

$resultsByIndex​

Type​

Array<any>!

Description​

An array of zero-indexed resolver results.