While the accepted answer isn't technically wrong, it doesn't answer the original question nor the follow up question in the comments, which was what I came here looking for. But I figured it out, so here goes.
If you want to find all Posts that have Users (and only the ones that have users) where the SQL would look like this:
SELECT * FROM posts INNER JOIN users ON posts.user_id = users.id
Which is semantically the same thing as the OP's original SQL:
SELECT * FROM posts, users WHERE posts.user_id = users.id
then this is what you want:
Posts.findAll({
include: [{
model: User,
required: true
}]
}).then(posts => {
/* ... */
});
Setting required to true is the key to producing an inner join. If you want a left outer join (where you get all Posts, regardless of whether there's a user linked) then change required to false, or leave it off since that's the default:
Posts.findAll({
include: [{
model: User,
// required: false
}]
}).then(posts => {
/* ... */
});
If you want to find all Posts belonging to users whose birth year is in 1984, you'd want:
Posts.findAll({
include: [{
model: User,
where: {year_birth: 1984}
}]
}).then(posts => {
/* ... */
});
Note that required is true by default as soon as you add a where clause in.
If you want all Posts, regardless of whether there's a user attached but if there is a user then only the ones born in 1984, then add the required field back in:
Posts.findAll({
include: [{
model: User,
where: {year_birth: 1984}
required: false,
}]
}).then(posts => {
/* ... */
});
If you want all Posts where the name is "Sunshine" and only if it belongs to a user that was born in 1984, you'd do this:
Posts.findAll({
where: {name: "Sunshine"},
include: [{
model: User,
where: {year_birth: 1984}
}]
}).then(posts => {
/* ... */
});
If you want all Posts where the name is "Sunshine" and only if it belongs to a user that was born in the same year that matches the post_year attribute on the post, you'd do this:
Posts.findAll({
where: {name: "Sunshine"},
include: [{
model: User,
where: ["year_birth = post_year"]
}]
}).then(posts => {
/* ... */
});
I know, it doesn't make sense that somebody would make a post the year they were born, but it's just an example - go with it. :)
I figured this out (mostly) from this doc: