Eloquent group messages - sql

Question

I´m playing with Laravel´s eloquent and a MYSQL database
I need to display a list of conversations
this is my table structure
messages:
- id
- from_id
- to_id
- message
- read
|----|-----------|---------|-------|------|
| id | message | from_id | to_id | read |
|----|---------------------|--------------|
| 1 | hello | 1 | 2 | 1 |
| 2 | hey | 2 | 1 | 0 |
| 3 | there | 2 | 1 | 0 |
| 4 | hi! | 3 | 1 | 1 |
|----|-----------|---------|-------|------|
users:
- id
- name
|-----------|
| id | name |
|-----------|
| 1 | john |
| 2 | mary |
| 3 | jack |
|-----------|
expected:
if I´m user 1 (it should show me the last message and the count of unread
|----|------|---------|--------|
| id | name | message | unread |
|----|------|---------|--------|
| 3 | mary | there | 2 |
| 4 | jack | hi! | 0 |
|----|------|-------- |--------|
I´m not sure if this is the right table structure for what I want to do but the SQL should be something like
SELECT users.name, messages.message
FROM users, messages
WHERE messages.from_id = 1 OR messages.to_id = 1
GROUP BY ??
ORDER BY messages.id DESC
I´m not sure how to GROUP because if I group by messages.from_id = 1 it will only show messages I sent and not messages I received. please help me thing :)
also how to handle the read status? for sure that read attribute is something like the to_id will set to 1. how to check that in the query as well?

Answer 1

THere's a couple of things I see here.
1. while aggregating your data to count the number of unread emails, you are still showing at least one message which indicates message text. In the expected response:
|----|------|---------|--------|
| id | name | message | unread |
|----|------|---------|--------|
| 3 | mary | there | 2 |
| 4 | jack | hi! | 0 |
|----|------|-------- |--------|
You have two unread messages for mary, however the message column says there, which is only the message of one the two unread emails.
I'm just wondering if that's on purpose.
However, to get you where you need to go,
you have the read column which appears binary in nature: 1 for messages read, 0 for messages not read.
That being said, you can utilize that logic to count the number of unread messages by using the algorithm: count(read) - sum(read).
the second thing is your joins. You have to join the tables together in order to establish names to user_ids. in your case, you are not using a join at all but filtering by field. if you want a list of from users, filtered by the to users, then you need to join the from_id to the user_id so you can get the name.
There you can group by name and at least get id, name, unread. as forth in this example:
SELECT users.name, count(read) - sum(read) as unread
FROM users, messages
WHERE users.id = messages.from_id and messages.to_id = 1 --to me
GROUP BY users.name
ORDER BY messages.from_id ASC
in laravel ORM, try this (I know I"m close, but I'm mobile and haven't been able to test it, so play around):
$users = DB::table('messages')
->select(DB::raw('users.name, count(read) - sum(read) as unread'))
->join('users', 'users.id', '=', 'messages.from_id')
->where('to_id', '=', 1)
->orWhere('from_id', '=', '1')
->groupBy('users.name')
->orderBy('messages.from_id','ASC')
->get();
Try this.
UPDATE 1:
to purposely get the "latest" message with the list:
select u.name, fm.message, count(m.unread) - sum(m.unread) as unread,
case when m.from_id = 1 then 'sent'
when m.to_id = 1 then 'received'
else null
end status
from messages m
join users u on u.id = m.from_id
left join (
Select max(id) as id, from_id, message from messages group by from_id
) fm on m.from_id = fm.from_id
where m.from_id = 1 or m.to_id = 1
group by u.name;
Eloquent:
DB::table('messages')
->select('u.name', 'fm.message', 'count(m.read) - sum(m.read) as unread', 'case when m.from_id = 1 then "sent" when m.to_id = 1 then "received" else null end status')
->join(users u', 'u.id', '=', 'u.from_id')
->leftjoin(DB::raw('Select max(id) as id, from_id, message from messages group by from_id', 'm.from_id', 'fm.from_id'))
->groupBy('users.name')
->orderBy('messages.from_id','ASC')
->get();