Sequelize: get MIN/MAX Dates from association - mysql

Question

I have to tables - one for events and another one for the dates (start-end) this event is "active".
id name
-- ----
1 event 1
2 event 2
And then the EventDates
eventId start end
------- ----- ---
1 2018-01-14 2018-01-15
1 2018-01-17 2018-01-18
2 2018-02-14 2018-02-18
Events and EventDates are setup using hasMany()
Event.DATES = Event.hasMany(models.EventDates, {
as: 'dates',
foreignKey: 'eventId',
});
Querying for all Events including the EventDates like this:
await Event.findAll({
include: [{ association: Event.DATES }]
});
returns a nested Event list with all the EventDates - great.
[
{
id: 1,
name: 'event 1',
dates: [
{
start: '2018-01-14',
end: '2018-01-15',
},
{
start: '2018-01-17',
end: '2018-01-18',
},
],
},
{
id: 2,
name: 'event 2',
dates: [
{
start: '2018-02-14',
end: '2018-02-18',
},
],
}
]
But now I want to add a maxEndDate to an Event so I can check if it still active or if all EventDates are in the past. I can do that manually adding another LEFT JOIN like this:
# ...
LEFT OUTER JOIN (SELECT eventId, MAX(end)
FROM `EventDates`
GROUP BY eventId) dates
ON `Event`.`id` = `dates`.`eventId`
# ...
But how could I achieve the same thing with Sequelize?
[
{
id: 1,
name: 'event 1',
maxEndDate: ??,
dates: [
{
start: '2018-01-14',
end: '2018-01-15',
},
{
start: '2018-01-17',
end: '2018-01-18',
},
],
},
{
id: 2,
name: 'event 2',
maxEndDate: ??,
dates: [
{
start: '2018-02-14',
end: '2018-02-18',
},
],
}
]

Answer 1

It very tricky to get result with group by and has many association , but at last I found the way and here it is :
Event.findAll({
raw : true,
attributes : [ 'Event.*' , 'EventDates.eventId' , [sequelize.fn('max', sequelize.col('EventDates.end')),'end']],
include : {
model : EventDates ,
attributes :[]
},
group : ['Event.id','EventDates.eventId']
})
I think you can achieve your last out put that by this , I haven't tried this but this is the way you can go ahead
Event.findAll({
raw : true,
attributes : [ 'Event.*' , 'dates.*' , 'EventDates.eventId' , [sequelize.fn('max', sequelize.col('EventDates.end')),'end']],
include : [
{
model : EventDates ,
attributes :[]
},
{
model : EventDates ,
as : 'dates',
required : false,
separate : true
}
]
group : ['Event.id','EventDates.eventId']
})