NowGraphQLService class - iOS

The NowGraphQLService class provides functions that enable you to make requests using GraphQL queries against data on your ServiceNow instance through its GraphQL REST API.

Table 1. Properties

Name	Type	Description
configuration	NowServiceConfiguration	Configuration settings provided when the service was initialized.

NowGraphQLService - execute(query: GraphQLQuery) async throws

Executes the specified GraphQL query.

Table 2. Parameters

Name	Type	Description
query	String	GraphQL query to execute.

Table 3. Returns

Type	Description
Data	Returned when the method is successful. Query data generated from the specified query.
NowDataError	Thrown when the method fails. accessToken(AccessTokenProviderError) AccessTokenProviderError: The access token provider's error code or message. accessTokenRetrievalFailed userSessionError(_ error: Error) Thrown when there is an error in the access token. attachmentValidation Thrown when an attachment fails validation. badResponse(statusCode: HTTPStatusCode) HTTPStatusCode: Status code received from the instance. Thrown when a request returns an unexpected response cannotDecodeModel(DecodingError) DecodingError: Decoding error detected. Thrown when a Codable model cannot be decoded from JSON. cannotDecodeProperty(type: Any, from: String) type: Wrapped type to decode from a string. from: String to decode to the specified type. Thrown when a string-wrapped value cannot be decoded from JSON. cannotEncodeModel(EncodingError) EncodingError: Encoding error detected. Thrown when a Codable model cannot be encoded to JSON. cannotParseResponse Thrown when a response from the instance cannot be parsed into its expected format. invalidURL Thrown when a URL cannot be formed. For example, if the string contains characters that are illegal in a URL or is an empty string. missingAttachmentMetadata Thrown when the attachment metadata header is missing. missingServiceConfiguration Thrown when an expected service configuration is missing. missingSysID Thrown when an expected sys_id parameter is missing. network(NetworkServiceError) genericError(String) operationCanceled service​Disabled serverError(Error) systemError(Error) Thrown when a network service encountered an error.

The following code example shows how to call this method.

private func fetchArticles() async throws -> [Article] { 
    guard let graphQLService = graphQLService else { 
        throw ArticleListError.invalidGraphQLService 
    }         

    do {
        let data = try await graphQLService.execute(GraphQLQuery(query: recentlyPublishedQuery))
        let articles = try dataToArticleList(data)
    } catch let error as NowDataError {
        throw ArticleListError.fetchError(error)
    } catch {
        throw error
    }
} 
  
private let recentlyPublishedQuery = 
""" 

{
  GlideRecord_Query {
    kb_knowledge(queryConditions: "active=true^ORDERBYpublishedDESC" pagination: { limit: 10, offset: 0 }) {
      _results { 
        sys_id {
          value
        },
        number {
          displayValue
        },
        short_description {
          displayValue
        },
        author {
          displayValue
        }
        published {
          displayValue
        }
      }
    }
  }
}
"""

NowGraphQLService - execute(query: GraphQLQuery, completion: @escaping (Result<Data, NowDataError>))

Executes the specified GraphQL query.

Table 4. Parameters

Name	Type	Description
query	String	GraphQL query to execute.
completion	@escaping (Result<Data, NowDataError>)	Completion handler to execute after the query is complete. Return values: Success: Returns query data. Error: NowDataError

Table 5. Returns

Type	Description
None

gqlService.execute(GraphQLQuery(query: myQuery)) { result in 
  switch result { 
  case .success(let data): 
    // use data 
  case .failure(let error): 
    // handle error 
  } 
}

NowGraphQLService - init(configuration: NowServiceConfiguration, coreServiceProvider: NowCoreServiceProviding)

Creates a NowGraphQLService based on the specified parameters.

Table 6. Parameters

Name	Type	Description
configuration	NowServiceConfiguration	Configuration parameters to use when initializing the service, such as the bundle ID of the application integrating with the service and the URL of the ServiceNow instance that the NowGraphQLService wants to access.
coreServiceProvider	NowCoreServiceProviding	Optional. Core service provider. Note: Currently this parameter is required even though it is shown as optional. Default: nil

NowGraphQLService - publisher(for query: GraphQLQuery)

Creates a publisher to request GraphQL data.

Note:

This method has been deprecated. You should use the async/await implementation of the method instead.

Table 7. Parameters

Name	Type	Description
for query	GraphQLQuery	GraphQL query string to execute.

Table 8. Returns

Type	Description
AnyPublisher<Data, NowDataError>	Success: GraphQL data set. Failure: NowDataError

The following code example shows how to call this function.

private func fetchArticles() -> AnyPublisher<[Article], ArticleListError> {
  guard let graphQLService = graphQLService else {
    return Fail(error: .invalidGraphQLService).eraseToAnyPublisher()
  }
        
  return graphQLService.publisher(for: GraphQLQuery(query: recentlyPublishedQuery))
    .mapError({ dataError -> ArticleListError in
      .fetchError(dataError)
    })
    .flatMap(dataToArticleList)
    .eraseToAnyPublisher()
}