No eager loading support? about gorm HOT 3 CLOSED

Because gorm can't know when should eager loading related structs, so just don't do it.

And you have to do something like this in your application ;(

db.First(&user)
db.Model(&user).Related(&user.Emails)

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I stumbled over this as well.. I guess there should be a nicer solution for this.
Can we maybe introduce a .WithRelated() switch to trigger loading of relations?

The current approach gets kind of hairy for more complex relations.
In my current project I have to load multiple relations on a returned result of multiple rows.

Right now I do this which strikes down my query times quite hard...

start := time.Now()
for idx, a := range sliceOfModelA {
    txn.Model(&a).Related(&(sliceOfModelA[idx].modelB))
    txn.Model(&a).Related(&(sliceOfModelA[idx].modelC))
    txn.Model(&a).Related(&(sliceOfModelA[idx].modelD))
}
revel.INFO.Printf("LookupRelated took %v for %d entries.", time.Since(start), len(aslice))

While writing this I came up with an Idea to perform the relation lookups more efficient. I hacked together a proof of concept here.

I tried if you can Scan into multiple Objects by using an []interface{} containing the fields of the result and expanding it in like so: .Scan(fields...).
Long story short, it works!
This allows you to construct SQL-Querries which JOIN together your relations and Scan them in one go.

If you can give me a hin where to start, I will try to turn this into a pull request but i'm currently to unfamiliar with gorm's code base to know if this is feasible.

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I played with this Idea some more, generalising it with reflection. I uploaded it in this playground.

I'd love to hear some suggestion to this approach. Obviously which fields to use as the join keys should be more Intelligent.

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