mirror of https://github.com/zulip/zulip.git
53 lines
1.5 KiB
Markdown
53 lines
1.5 KiB
Markdown
# Unread message synchronization
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In general displaying unread counts for all channels and topics may require
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downloading an unbounded number of messages. Consider a user who has a muted
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channel or topic and has not read the backlog in a month; to have an accurate
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unread count we would need to load all messages this user has received in the
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past month. This is inefficient for web clients and even more for mobile
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devices.
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We work around this by including a list of unread message ids in the initial
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state grouped by relevant conversation keys. This data is included in the
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`unread_msgs` key if both `update_message_flags` and `message` are required
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in the register call.
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```json
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{
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"count": 4,
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"huddles": [
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{
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"user_ids_string": "3,4,6",
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"unread_message_ids": [
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34
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]
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}
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],
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"streams": [
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{
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"stream_id": 1,
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"topic": "test",
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"unread_message_ids": [
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33
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]
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}
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],
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"pms": [
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{
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"sender_id": 3,
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"unread_message_ids": [
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31,
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32
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]
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}
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],
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"mentions": [31, 34]
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}
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```
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Three event types are required to correctly maintain the `unread_msgs`. New
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messages can be created without the unread flag by the `message` event type.
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The unread flag can be added and removed by the `update_message_flags` event,
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and the topic of unread messages can be updated by the `update_message` event
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type.
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