GraphQL

Since Camel 3.0

Only producer is supported

The GraphQL component is a GraphQL client that communicates over HTTP and supports queries and mutations, but not subscriptions. It uses the Apache HttpClient library.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-graphql</artifactId>
    <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The GraphQL component supports 2 options, which are listed below.

Name Description Default Type

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

boolean

Endpoint Options

The GraphQL endpoint is configured using URI syntax:

graphql:httpUri

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

httpUri (producer)

Required The GraphQL server URI.

URI

Query Parameters (12 parameters)

Name Description Default Type

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

boolean

operationName (producer)

The query or mutation name.

String

proxyHost (producer)

The proxy host in the format hostname:port.

String

query (producer)

The query text.

String

queryFile (producer)

The query file name located in the classpath.

String

queryHeader (producer)

The name of a header containing the GraphQL query.

String

variables (producer)

The JsonObject instance containing the operation variables.

JsonObject

variablesHeader (producer)

The name of a header containing a JsonObject instance containing the operation variables.

String

accessToken (security)

The access token sent in the Authorization header.

String

jwtAuthorizationType (security)

The JWT Authorization type. Default is Bearer.

String

password (security)

The password for Basic authentication.

String

username (security)

The username for Basic authentication.

String

Message Body

If the variables and variablesHeader parameters are not set and the IN body is a JsonObject instance, Camel will use it for the operation’s variables. If the query and queryFile parameters are not set and the IN body is a String, Camel will use it as the query. Camel will store the GraphQL response from the external server on the OUT message body. All headers from the IN message will be copied to the OUT message, so headers are preserved during routing. Additionally Camel will add the HTTP response headers as well to the OUT message headers.

Examples

Queries

Simple queries can be defined directly in the URI:

from("direct:start")
    .to("graphql://http://example.com/graphql?query={books{id name}}")

The body can also be used for the query:

from("direct:start")
    .setBody(constant("{books{id name}}"))
    .to("graphql://http://example.com/graphql")

The query can come from a header also:

from("direct:start")
    .setHeader("myQuery", constant("{books{id name}}"))
    .to("graphql://http://example.com/graphql?queryHeader=myQuery")

More complex queries can be stored in a file and referenced in the URI:

booksQuery.graphql file:

query Books {
  books {
    id
    name
  }
}
from("direct:start")
    .to("graphql://http://example.com/graphql?queryFile=booksQuery.graphql")

When the query file defines multiple operations, it’s required to specify which one should be executed:

from("direct:start")
    .to("graphql://http://example.com/graphql?queryFile=multipleQueries.graphql&operationName=Books")

Queries with variables need to reference a JsonObject instance from the registry:

@BindToRegistry("bookByIdQueryVariables")
public JsonObject bookByIdQueryVariables() {
    JsonObject variables = new JsonObject();
    variables.put("id", "book-1");
    return variables;
}

from("direct:start")
    .to("graphql://http://example.com/graphql?queryFile=bookByIdQuery.graphql&variables=#bookByIdQueryVariables")

A query that accesses variables via the variablesHeader parameter:

from("direct:start")
    .setHeader("myVariables", () -> {
        JsonObject variables = new JsonObject();
        variables.put("id", "book-1");
        return variables;
    })
    .to("graphql://http://example.com/graphql?queryFile=bookByIdQuery.graphql&variablesHeader=myVariables")

Mutations

Mutations are like queries with variables. They specify a query and a reference to a variables bean:

addBookMutation.graphql file:

mutation AddBook($bookInput: BookInput) {
  addBook(bookInput: $bookInput) {
    id
    name
    author {
      name
    }
  }
}

[source,java

@BindToRegistry("addBookMutationVariables")
public JsonObject addBookMutationVariables() {
    JsonObject bookInput = new JsonObject();
    bookInput.put("name", "Typee");
    bookInput.put("authorId", "author-2");
    JsonObject variables = new JsonObject();
    variables.put("bookInput", bookInput);
    return variables;
}

from("direct:start")
    .to("graphql://http://example.com/graphql?graphql?queryFile=addBookMutation.graphql&variables=#addBookMutationVariables")

Spring Boot Auto-Configuration

When using graphql with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-graphql-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 3 options, which are listed below.

Name Description Default Type

camel.component.graphql.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.graphql.enabled

Whether to enable auto configuration of the graphql component. This is enabled by default.

Boolean

camel.component.graphql.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean