Two different classes used for type Page

[erDuo10]

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllAuthors(java.lang.Integer,java.lang.Integer)
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllMyAuthors(java.lang.Integer,java.lang.Integer)

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllBooks(java.lang.Integer,java.lang.Integer)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:640) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
... 142 common frames omitted
Caused by: com.coxautodev.graphql.tools.SchemaClassScannerError: Two different classes used for type Page:

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllAuthors(java.lang.Integer,java.lang.Integer)
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllMyAuthors(java.lang.Integer,java.lang.Integer)

interface org.springframework.data.domain.Page:
| return type of method public org.springframework.data.domain.Page com.erduo.FirstGraphql.resolver.Query.findAllBooks(java.lang.Integer,java.lang.Integer)
at com.coxautodev.graphql.tools.SchemaClassScanner.handleFoundType(SchemaClassScanner.kt:319) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.handleFoundType(SchemaClassScanner.kt:293) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.scanResolverInfoForPotentialMatches(SchemaClassScanner.kt:268) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.handleRootType(SchemaClassScanner.kt:119) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaClassScanner.scanForClasses(SchemaClassScanner.kt:77) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaParserBuilder.scan(SchemaParserBuilder.kt:169) ~[graphql-java-tools-5.7.1.jar:na]
at com.coxautodev.graphql.tools.SchemaParserBuilder.build(SchemaParserBuilder.kt:210) ~[graphql-java-tools-5.7.1.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration.schemaParser(GraphQLJavaToolsAutoConfiguration.java:115) ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c.CGLIB$schemaParser$1() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c$$FastClassBySpringCGLIB$$16f0171.invoke() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.2.0.RELEASE.jar:5.2.0.RELEASE]
at graphql.kickstart.tools.boot.GraphQLJavaToolsAutoConfiguration$$EnhancerBySpringCGLIB$$555cbf8c.schemaParser() ~[graphql-kickstart-spring-boot-autoconfigure-tools-6.0.0.jar:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]
... 143 common frames omitted

java code

import org.springframework.data.domain.Page;

import com.coxautodev.graphql.tools.GraphQLQueryResolver;
import com.erduo.FirstGraphql.model.entity.business.Author;
import com.erduo.FirstGraphql.model.entity.business.Book;
import com.erduo.FirstGraphql.model.input.OffsetBasedPageRequest;
import com.erduo.FirstGraphql.service.AuthorService;
import com.erduo.FirstGraphql.service.BookService;

public class Query implements GraphQLQueryResolver {
private BookService bookService;
private AuthorService authorService;

public Query(AuthorService authorService, BookService bookService) {
	this.authorService = authorService;
	this.bookService = bookService;
}

public Page<Book> findAllBooks(Integer skip, Integer first) {		
	System.out.println("--------findAllBooks");
	return bookService.findAllBooks(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Book> findAllMyBooks(Integer skip, Integer first) {
	System.out.println("--------findAllMyBooks");
	return bookService.findAllBooksByUser(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Author> findAllAuthors(Integer skip, Integer first) {
	System.out.println("--------findAllAuthors");
	return authorService.findAllAuthors(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public Page<Author> findAllMyAuthors(Integer skip, Integer first) {
	System.out.println("--------findAllMyAuthors");
	return authorService.findAllAuthorsByUser(new OffsetBasedPageRequest(skip.intValue(), first.intValue()));
}

public long countAllBooks() {
	return bookService.countAllBooks();
}

public long countAllMyBooks() {
	return bookService.countAllBooksByUser();
}

public long countAllAuthors() {
	return authorService.countAllAuthors();
}

public long countAllMyAuthors() {
	return authorService.countAllAuthorsByUser();
}
}

schema code

union SearchResult = Book | Author

type Page {
number: Int
size: Int
totalPages: Int
totalElements: Int
content: [SearchResult]
}

type Book{
id: ID!
title: String!
isbn: String!
pageCount: Int
author: Author
}

input CreateBookInput {
title: String!
isbn: String!
pageCount: Int
author: ID!
}

extend type Query {
findAllBooks(skip: Int = 0, first: Int = 0) : Page!
findAllMyBooks(skip: Int = 0, first: Int = 0) : Page!
countAllBooks: Long!
countAllMyBooks: Long!
}

extend type Mutation {
newBook(input:CreateBookInput!) : Book!
deleteBook(id: ID!) : Boolean
updateBookPageCount(pageCount: Int!, id: ID!) : Book!
}

type Author {
id: ID!
firstName: String!
lastName: String!
}

input CreateAuthorInput {
firstName: String!
lastName: String!
}

type Query {
findAllAuthors(skip: Int = 0, first: Int = 0) : Page!
findAllMyAuthors(skip: Int = 0, first: Int = 0) : Page!
countAllAuthors: Long!
countAllMyAuthors: Long!
}

type Mutation {
newAuthor(input: CreateAuthorInput!) : Author!
}

[oliemansm]

That's because the generic return type Page<Book> and Page<Author> are mapped to two different responses. You need to define separate types per case, so PageBook and PageAuthor for example. You could try to lose the generics and just return Page. That might work if you're lucky.

[erDuo10]

thanks, I will have a try.

[amr]

@oliemansm is this a straightforward improvement that can be considered?

[oliemansm]

@amr You mean to support generics for Page return type? It is, but it's very low on our to do list. So we would be very happy with anybody wanting to contribute to make that work.