Pagination not working with GetTimelinePublic and Mastodon 2.6.5

[marians]

I tried using go-mastodon against the https://chaos.social instance, which uses version 2.6.5 according to https://chaos.social/api/v1/instance, with following code:

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/mattn/go-mastodon"
)

func main() {
	ctx := context.Background()

	c := mastodon.NewClient(&mastodon.Config{
		Server: "https://chaos.social",
	})

	pg := mastodon.Pagination{}

	for {
		timeline, err := c.GetTimelinePublic(ctx, false, &pg)
		if err != nil {
			log.Println(err)
		}

		for _, item := range timeline {
			fmt.Printf("%#v\n", item)
		}

		if pg.MaxID == "" {
			break
		}

		time.Sleep(10 * time.Second)
	}
}

This quits with the output

2018/12/21 07:25:04 strconv.ParseInt: parsing "": invalid syntax

which is coming from

go-mastodon/mastodon.go

Line 296 in 4def10a

id, err := strconv.ParseInt(val, 10, 64)

I have an experimental fix that works for me here for the simple purpose of the above code: https://github.com/marians/go-mastodon/pull/1/files

My understanding of the Mastodon API version differences is not deep enough to tell when min_id has been introduced, where it is used, whether since_id is still in use etc. So I can't provide a PR currently that makes pagination work in all cases. Hopefully the description is enough for others to do so. Thanks!

[mattn]

@178inaba Can you handle this issue?

[178inaba]

@mattn OK!

[178inaba]

I confirmed the following response in the Link header.

<https://chaos.social/api/v1/timelines/public?max_id=101306164022079793>; rel="next", <https://chaos.social/api/v1/timelines/public?min_id=101306170504618280>; rel="prev"

It seems that this change came in at 2.6.0.
https://github.com/tootsuite/mastodon/releases/tag/v2.6.0

Support backwards pagination (#8736)

The new pagination param min_id is the symmetrical opposite of max_id, i.e. it can be used for stepwise pagination from older to newer statuses. The difference to since_id is that since_id will always return the latest statuses, just merely cut off by the provided ID. The new param is supported on all API methods that return statuses.

I will show my recognition as an example.

For example, suppose you have a status ID like the one below.
1, 2, 3 ... 98, 99, 100

In this case, the response should be as follows.
/api/v1/timelines/public?min_id=1&limit=5 -> 2, 3, 4, 5, 6
/api/v1/timelines/public?since_id=1&limit=5 -> 96, 97, 98, 99, 100
/api/v1/timelines/public?since_id=97 -> 98, 99, 100
/api/v1/timelines/public?since_id=50&max_id=54 -> 51, 52, 53

since_id is still in use, but I think that the Link header should be modified since it uses min_id.

@marians Can you submit your pull request to this repository?

[marians]

@178inaba I'd rather not do that. Because (a) the change is trivial and (b) according to my understanding, especially from your comment, this will break pagination for servers < 2.6.0.

[178inaba]

@marians Thank you.
I will consider how to fix it.

[178inaba]

@marians I am sorry to be late.
I fixed it with #90 !
Please check it!

[marians]

Thanks! Not sure when I'll be able to test this. Will close for now.

[mattn]

@178inaba Thank you so much!