Question passing an Int slice into WhereIn

[fi0]

how do I pass a slice into whereIn?

example
qm.WhereIn("id in ?", 1, 2, 3)

these won't work

ids := []int{1, 2, 3}
qm.WhereIn("id in ?", ids)

ids := []int{1, 2, 3}
qm.WhereIn("id in ?", ids...)

[aarondl]

The bottom one should be working, can you turn on debug mode and show what kind of query or error you're getting? Need more information to determine what the problem is :)

[payaaam]

I have had problems with this too. The solution is to convert your slice to []interface{}.

Example

ids := []int{1, 2, 3}
convertedIDs := make([]interface{}, len(ids))
for index, num := range ids {
	convertedIDs[index] =  num
}

qm.WhereIn("id IN ?", convertedIDs...)

[fi0]

thank you it works

[aarondl]

I actually think we should try to fix this. It shouldn't really behave like this and we may be able to do something about it.

[ceshihao]

This problem is from golang/go#16235
It seems to be fixed in go1.9 by supporting custom import types.

[aarondl]

Unfortunately after looking into it, there is no way to be able to do this :(

It's possible to use arrays in general as ceshihao is suggesting, but that requires driver support and is actually usable today without any changes.
It's a Go problem that we can't convert the slices easily. :(

[tonyhb]

@aarondl I'm pretty sure we can fix this with a quick bit of reflection.

Right now we always expect that a user splats their variadic arg. That's the root cause of the issue.

For argument's sake, lets allow people to call WhereIn with a slice (qm.WhereIn("id IN ?", ids) where ids is a slice).

Then, we inspect our variadic argument to see if len is 1. If so, we may have a slice passed. We can then fix WhereIn as follows:

func WhereIn(clause string, args ...interface{}) QueryMod {
	if len(args) == 1 && reflect.TypeOf(args[0]).Kind() == reflect.Slice {
		val := reflect.ValueOf(args[0])
		slice := make([]interface{}, val.Len())
		for i := 0; i < val.Len(); i++ {
			slice[i] = val.Index(i)
		}
		return WhereIn(clause, slice...)
	}

	fmt.Printf("continue: %vv", args)
}

We use reflect to see if the only item in arg is a slice, and if so we handle the conversion of slice to interfaces for people automatically. Type safe, no impact, better UX.

I'll make a PR now

[tonyhb]

Here's a quick demo: https://play.golang.org/p/0rrgz5cwFtj

[JC1738]

Still doesn't work unless you use something like this

func ToSliceOfAny[T any](s []T) []any { result := make([]any, len(s)) for i, v := range s { result[i] = v } return result }