how to using a db function in where sentence via sequelize - node.js

Question

I want to find an average value of this week and group by dayofweek, so I writen this sql, the sql is work well, but how can I achieve the same purpose via sequelize.
select dayofweek(datetime), avg(value) from Temperatures where week(datetime) = week(now()) group by dayofweek(datetime);
And here is my Temperatures table:
| field | type |
|----------|-------------|
| uuid | char(36) |
| value | float |
| datetime | datetime |
I've read the document of sequelize, but it seems that there is no clear explanation of how to using a function after where sentence, the condition is a function but not a field.
I have tried under way, but it's not work
where: {
[Sequelize.Op.eq]: [
sequelize.fn('week', Temperature.sequelize.fn('now')),
sequelize.fn('week', Temperature.sequelize.col('datetime')),
]
},
Thank your for your help!

Answer 1

You can use sequelize.fn for that , something like this :
[sequelize.fn('dayofweek', sequelize.col('datetime')), 'datetime']
For more details DO READ

Answer 2

Finally, I found the following method works well
return Temperature.findAll({
attributes: [
[Temperature.sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')), 'dayofweek'],
[Temperature.sequelize.fn('AVG', Temperature.sequelize.col('value')), 'value'],
],
where: sequelize.where(sequelize.fn('week', Temperature.sequelize.fn('now')), sequelize.fn('week', Temperature.sequelize.col('datetime'))),
group: sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')),
});
and if I need more conditional filters, just add an [Op.and] operator
return Temperature.findAll({
attributes: [
[Temperature.sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')), 'dayofweek'],
[Temperature.sequelize.fn('AVG', Temperature.sequelize.col('value')), 'value'],
],
where: {
[Sequelize.Op.and]: [
sequelize.where(sequelize.fn('week', Temperature.sequelize.fn('now')), sequelize.fn('week', Temperature.sequelize.col('datetime'))),
]
},
group: sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')),
});
here is the sql generated
SELECT dayofweek(`datetime`) AS `dayofweek`, AVG(`value`) AS `value` FROM `Temperatures` AS `Temperature` WHERE (week(now())=week(`datetime`)) GROUP BY dayofweek(`datetime`);