Slice of Struct or Slice of Pointers

[zibi94]

Why was it decided to return a slice of pointers instead of a slice of structures.

sqlboiler/templates/main/01_types.go.tpl

Line 19 in 35bb36b

{{$alias.UpSingular}}Slice []*{{$alias.UpSingular}}

Referring to the articles:
https://andrii-kushch.medium.com/go-what-to-return-a-slice-of-structs-vs-a-slice-of-pointers-42647912530a
https://medium.com/@philpearl/bad-go-slices-of-pointers-ed3c06b8bb41

The authors' conclusion is that it is better to use a slice of structures.

I would like to ask if there was any particular reason for this decision.

Maybe this is an idea for improvement.

[stephenafamo]

When I started maintaining SQLBoiler, things were already this way and I've never thought about it.

While I would like to dig into this and change it if there are significant benefits, it would be a huge breaking change so it cannot even be considered before we are ready for a new major version.

[adatob]

From the queries/reflect.go :

// Valid types to bind to are: *Struct, []*Struct, and []Struct. Keep in mind
// if you use []Struct that Bind will be doing copy-by-value as a method
// of keeping heap memory usage low which means if your Struct contains
// reference types/pointers you will see incorrect results, do not use
// []Struct with a Struct with reference types.

I also noticed incorrect results after binding to []Struct when I used the custom reference type field inside for jsonb type column scanning. Using the []*Struct the results are correct.

I believe this is part of the reason for using []*Struct in models.

[xrn]

@stephenafamo how are you looking into this at https://github.com/stephenafamo/bob project?

[stephenafamo]

Bob also uses a slice of pointers. This is for two reasons:

1. Bob heavily uses generics, and it is very difficult to express getting a slice to the non-pointer version of another type. It is possible, but would make things very difficult to read, and by extension, debug.
2. Since the "one" methods all act on the pointer, having a slice of structs may be annoying to use when you have the slice and need to use a singular struct.

[xrn]

Thank you for explanation