Query builder patterns for nullable fields | Dagger | Page 1

keen cipher Sep 30, 2022, 8:45 PM

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I was having trouble following this so took the liberty of creating a thread @ruby ore @dry siren 🙂

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I was wondering about this a while back (when writing my fantasy go DX) and the LLB pattern seemed the most natural

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After all we're using the llb pattern for chaining too...

dry siren Sep 30, 2022, 8:58 PM

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yeah, so I think the LLB pattern is great from a code readability standpoint, my only complaint is sometimes it's hard to discover the available options. having LSP completion helps a lot since it can infer that you're trying to call a method with a e.g. RunOption return type, but it's not as simple as just setting fields on a struct.

having said all that, I still think it's probably the best choice. having to always pass in a nil options struct or nil for every optional parameter would be kind of clunky.

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it's also nice that Go docs group them together properly: https://pkg.go.dev/github.com/moby/buildkit@v0.10.4/client/llb#RunOption (particularly in the big function list up top, which I can't deep-link to)

keen cipher Sep 30, 2022, 9:00 PM

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I've had that experience getting lost in the llb go docs

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Maybe the pattern could be refined? For example instead of:

Directory(DirectoryID("foo"))

We could do:

Directory(DirectoryOpts().WithID("foo"))

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meh

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Actually why is a struct not viable? Because of string pointers being weird?

dry siren Sep 30, 2022, 9:30 PM

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a struct would be simple and really not that bad. you mean like .Directory(&DirectoryOpts{ID: "foo"})? and .Directory(nil)? I think the GitHub API works that way.

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the only downside imo is having the nil (or worse, DirectoryOpts{}) but that's really not a big deal. and maybe we could make it a sneaky variadic arg

keen cipher Sep 30, 2022, 9:31 PM

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Yeah except it would have to be .Directory(&DirectoryOpts{ID: &"foo"}) or .Directory(&DirectoryOpts{ID: nil}) which is not as slick, as @ruby ore mentioned

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In practice it won't be a problem for IDs, since you'd never pass a literal string as ID

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but same problem for eg. path

dry siren Sep 30, 2022, 9:32 PM

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oh yeah true. with generics we can have a func Ptr[T any](x T) *T { return &x } - but it's still a bit clunky

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(i think that'll end up in stdlib someday)

#Query builder patterns for nullable fields