GraphQL + SPQR + Spring Boot Starter 2021

Project setup / Dependencies

Add the following dependencies to your maven project:

<dependency>
    <groupId>io.leangen.graphql</groupId>
    <artifactId>graphql-spqr-spring-boot-starter</artifactId>
    <version>0.0.6</version>
</dependency>
<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphiql-spring-boot-starter</artifactId>
    <version>5.0.2</version>
</dependency>

To understand the main approaches SpqrAutoConfigurationregisters a component for each of the three built-in ResolverBuilderimplementations:

AnnotatedResolverBuilder– only provides methods annotated @GraphQLQuery, @GraphQLMutationor@GraphQLSubscription
PublicResolverBuilder– provides everything publicmethods from the original operation class (return methods voidare considered mutations)
BeanResolverBuilder– provides all getters as requests and setters as mutations (returned getters Publisher<T>count as subscriptions)

It is also possible to implement your own by implementing your ResolverBuilder interface.

Description of the main SPQR annotations

@ GraphQLApi is an analogue of a controller in which Query and Mutation are defined.

@GraphQLQuery – QUERY, analog of read queries

@ GraphQLMutation- MUTATION, analogue of create / delete / update queries

The rest of the annotations will be described below.

Description of the entity

The bank account entity has an account number (numberAccount), a currency (currency) and a current account (balance).

@Getter
@Setter
@Entity
@Table(name = "bank_account")
@FieldDefaults(level = AccessLevel.PRIVATE)
@NoArgsConstructor
public class BankAccountEntity {
    @Id
    String numberAccount;
    
    Currency currency;

    BigDecimal balance;
}

Let’s describe the dto for working with this entity:

@Getter
@Setter
@FieldDefaults(level = AccessLevel.PRIVATE)
public class BankAccountDto {
    @GraphQLId
    String numberAccount;

    @NotNull
    @GraphQLScalar
    @GraphQLInputField
    Currency currency;

    @NotNull
    @GraphQLInputField
    BigDecimal balance;
}

Here, the @GraphQLInputField annotation tells GraphQL that the current field will be the field to update or enter. Please note that the currency field has the @GraphQLScalar annotation – one of the ways to implement a complex scalar.

@RequiredArgsConstructor
@Component
@GraphQLApi
public class BankAccountDataFetcher {
    private final BankAccountService service;

    @GraphQLQuery(name = "getAllBalance")
    public List<BankAccountDto> getAll() {
        return service.getAll();
    }

    @GraphQLMutation(name = "createBankAccount", description = "create a new bank account")
    public BankAccountDto createBankAccount(@GraphQLArgument(name = "createBankAccountInput") @GraphQLNonNull BankAccountDto bankAccount) {
        return service.create(bankAccount);
    }

    @GraphQLMutation(name = "dispatchMoney", description = "dispatch money")
    public void dispatchMoney(@GraphQLArgument(name = "createDispatchMoneyInput") @GraphQLNonNull DispatchMoneyDto dispatchMoneyDto) {
        service.dispatchMoney(dispatchMoneyDto);
    }

    @GraphQLMutation(name = "removeBankAccount", description = "remove bank account")
    public void removeBankAccount(@GraphQLNonNull String numberAccount) {
        service.remove(numberAccount);
    }
}

The @GraphQLMutation annotation parameter name – specifies the method name for GraphQL, and description – respectively the description of the method for graphiql