Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

JavaScript resolver function reference for OpenSearch

The Amazon AppSync resolver for Amazon OpenSearch Service enables you to use GraphQL to store and retrieve data in existing OpenSearch Service domains in your account. This resolver works by allowing you to map an incoming GraphQL request into an OpenSearch Service request, and then map the OpenSearch Service response back to GraphQL. This section describes the function request and response handlers for the supported OpenSearch Service operations.

Request

Most OpenSearch Service request objects have a common structure where just a few pieces change. The following example runs a search against an OpenSearch Service domain, where documents are of type post and are indexed under id. The search parameters are defined in the body section, with many of the common query clauses being defined in the query field. This example will search for documents containing "Nadia", or "Bailey", or both, in the author field of a document:

export function request(ctx) {
  return {
    operation: 'GET',
    path: '/id/post/_search',
    params: {
      headers: {},
      queryString: {},
      body: {
        from: 0,
        size: 50,
        query: {
          bool: {
            should: [
              { match: { author: 'Nadia' } },
              { match: { author: 'Bailey' } },
            ],
          },
        },
      },
    },
  };
}

Response

As with other data sources, OpenSearch Service sends a response to Amazon AppSync that needs to be converted to GraphQL. .

Most GraphQL queries are looking for the _source field from an OpenSearch Service response. Because you can do searches to return either an individual document or a list of documents, there are two common response patterns used in OpenSearch Service:

List of Results

export function response(ctx) {
  const entries = [];
  for (const entry of ctx.result.hits.hits) {
    entries.push(entry['_source']);
  }
  return entries;
}

Individual Item

export function response(ctx) {
  return ctx.result['_source']
}

operation field

(REQUEST handler only)

HTTP method or verb (GET, POST, PUT, HEAD or DELETE) that Amazon AppSync sends to the OpenSearch Service domain. Both the key and the value must be a string.

"operation" : "PUT"

path field

(REQUEST handler only)

The search path for an OpenSearch Service request from Amazon AppSync. This forms a URL for the operation’s HTTP verb. Both the key and the value must be strings.

"path" : "/indexname/type"

"path" : "/indexname/type/_search"

When the request handler is evaluated, this path is sent as part of the HTTP request, including the OpenSearch Service domain. For example, the previous example might translate to:

GET https://opensearch-domain-name.REGION.es.amazonaws.com/indexname/type/_search

params field

(REQUEST handler only)

Used to specify what action your search performs, most commonly by setting the query value inside of the body. However, there are several other capabilities that can be configured, such as the formatting of responses.

Example 1

Return all documents with a city matching “seattle”:

export function request(ctx) {
  return {
    operation: 'GET',
    path: '/id/post/_search',
    params: {
      headers: {},
      queryString: {},
      body: { from: 0, size: 50, query: { match: { city: 'seattle' } } },
    },
  };
}

Example 2

Return all documents matching “washington” as the city or the state:

export function request(ctx) {
  return {
    operation: 'GET',
    path: '/id/post/_search',
    params: {
      headers: {},
      queryString: {},
      body: {
        from: 0,
        size: 50,
        query: {
          multi_match: { query: 'washington', fields: ['city', 'state'] },
        },
      },
    },
  };
}

Passing variables

(REQUEST handler only)

You can also pass variables as part of evaluation in your request handler. For example, suppose you had a GraphQL query such as the following:

query {
    searchForState(state: "washington"){
        ...
    }
}

The function request handler could be the following:

export function request(ctx) {
  return {
    operation: 'GET',
    path: '/id/post/_search',
    params: {
      headers: {},
      queryString: {},
      body: {
        from: 0,
        size: 50,
        query: {
          multi_match: { query: ctx.args.state, fields: ['city', 'state'] },
        },
      },
    },
  };
}