Relay pagination hasPreviousPage bug

[sebastiandev]

Every time you make a query with a first and after parameters, hasPreviousPage is false.

In order to reproduce, make a query

query {
    some_query(first: 1) {
      edges {
        node {
          name
        }
        cursor
      }
   }
}

And then another one using the cursor

query {
    some_query(first: 1, after: "somecursor") {
      pageInfo {
        hasNextPage
        hasPreviousPage
        startCursor
        endCursor
      }
      edges {
        node {
          name
        }
        cursor
      }
    }
}

In here I'm not sure why it adds 1, but at the end when calculating hasPreviousPage this will cause lower_offset to be equal to start_offset and return False

start_offset = max(
        slice_start - 1,
        after_offset,
        -1
) + 1

In here to calculate hasPreviousPage it only uses last so when you are using first. will always be false

    first_edge_cursor = edges[0].cursor if edges else None
    last_edge_cursor = edges[-1].cursor if edges else None
    lower_bound = after_offset + 1 if after else 0
    upper_bound = before_offset if before else list_length

    return connection_type(
        edges=edges,
        page_info=pageinfo_type(
            start_cursor=first_edge_cursor,
            end_cursor=last_edge_cursor,
            has_previous_page=isinstance(last, int) and start_offset > lower_bound,
            has_next_page=isinstance(first, int) and end_offset < upper_bound
        )
)

[sebastiandev]

Found the issue in the grpahql-relay repo. Closing this

[joealcorn]

For anybody that comes across this ticket, the issue mentioned above graphql-python/graphql-relay-py#12, and there's a PR open with a fix too: graphql-python/graphql-relay-py#14