如何使用支持分页的获取 api 从反应中编写 graphQL 查询？

Question

Information:

• I am using graphene-Django based backed
• Using Relay Node-based query

Tasks that I can perform:

• Write REST-based CRUD operations using fetch API in react.
• Simple GraphQL queries that involve fetching a list or single item from the server.
• Able to write GraphQL queries on GraphiQL

Want to do the following:

• fetch a list of items from the server with pagination, that fetches say 10 items and the option to go to the first page, last page, Prev Page, and Next Page.
• few examples would help

Answer 1

Solved by looking into various documentation, blogs, and my current requirement as:

const Post = (props) => {
  const [isLoading, setLoading] = useState(true);
  const [posts, setPosts] = useState([])
  const [offset, setOffset] = useState(0)
  const [hasPrev, setHasPrev] = useState(false)
  const [hasNext, setHasNext] = useState(false)
  const pageSize = 10

  useEffect(() => {
    const loadData = () => {
      setLoading(true)
      const requestOptions = getGraphqlRequestOptions(pageSize, offset)
      fetch(graphql_url, requestOptions)
        .then(response => {
          setLoading(false)
          return response.json()
        })
        .then(data => {
          setHasNext(data.data.allPosts.pageInfo.hasNextPage)
          setPosts(data.data.allPosts.edges)
          setHasPrev(offset !== 0)
        })
    }
    loadData()
  }, [offset]);

  const handleNextClick = () => {
    setOffset(offset + pageSize)
  };
  const handlePrevClick = () => {
    setOffset(offset - pageSize)
  };
  useEffect(()=> {
    document.title = "MyTitle"
    setOffset(0)
  }, []);

  return (
    <>
      ... code to display table
      <div className="row mb-5">
        <Button 
          variant="outline-primary"
          className="col-1 me-auto"
          disabled={!(hasPrev || isLoading)}
          size="sm" block
          onClick={!isLoading ? handlePrevClick : null}
        >
          {isLoading ?  'Loading...' : 'Previous'}
        </Button>
        <Button 
          className="col-1 ms-auto"
          disabled={!(hasNext || isLoading)}
          onClick={!isLoading ? handleNextClick: null}
          variant="outline-primary" size="sm" block
        >
          {isLoading ?  'Loading...' : 'Next'}
        </Button>
      </div>
    </>
  }

I was stuck because there were many options and no concrete example to implement this.
For example:

• We can use:
  1. query{allPosts(first:10, after:"last cursor"){pageInfo{hasPrevPage hasNextPage startCursor endCursor} edge{node{...}}}
  2. query{allPosts(first:10, offset:0){}} // currently used
  3. `query {allPosts(first:10, before:'start cursor'
  4. All above queries with last:10 instead of first:10, etc.
• Beside this it returns a PageInfo object having hasNextPage, hasPrevPage, startCursor, endCursor .
  • It was giving informations that were hard to understand
  • Using query (1) ie with first and after option, hasPrevPage was always false
  • Using query(3) ie with before option, hasNextPage was always false
  • So need to track whether the Next and Prev page exists was difficult.