[proposal] :map key=somefield query annotation

What do you want to change?

I frequently find myself converting the results from a query to a map, keyed by one of the fields. The code looks like this:

m := map[string]gendb.User{}
users, err := gendb.QueryUsers(ctx)
for _, u := range users {
  m[u.Username] = u
}

I've been holding off on this feature request hoping that generics would cleanly solve this, but solutions with generics aren't as pretty as I'd hoped. (Using a Map plus a lambda to return a field.)

Given that sqlc has all the information needed for this, it would be a neat convenience if sqlc could generate this boilerplate for me :)

I'm willing to send a PR if approved.

What database engines need to be changed?

No response

What programming language backends need to be changed?

Go

Allow for extra parameters to the queryType

Support `:many key=group_id` to return a map instead of a slice

Allow for extra parameters to the queryType

Support `:many key=group_id` to return a map instead of a slice

Allow for extra parameters to the queryType

Support `:many key=group_id` to return a map instead of a slice

What about also adding an option to allow multiple values per key? So instead of map[string]gendb.User one could get a map[string][]gendb.User

While not as common as the case with one value per key, I still sometimes find myself implementing this.

Another way of solving the problem:

generate a unexported method listXX

-- name: listXX :many
select * from xx

func (q *Queries) listXX(ctx context.Context) ([]SomeStruct, error)

manually write a exported one

func (q *Queries) ListXX(ctx context.Context) (map[string]SomeStruct, error) {
   s, _ := q.listXX(ctx)
   m := make(map[string]SomeStruct)
  for _, u := range s {
   m[u.SomeColumn] = u
 }

return m, nil
}

Pros:

less abstraction
being able to do many housekeeping stuff if needed, e.g, return a map[int]SomeStruct instead of map[string]SomeStruct because another packages wants a string column instead of a int one

Cons:

not that easy to find this way
some people might prefer the convenience solution as Jille said

Navigation Menu

Repository navigation

[proposal] `:map key=somefield` query annotation #2353

What do you want to change?

What database engines need to be changed?

What programming language backends need to be changed?

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

[proposal] :map key=somefield query annotation #2353

Description

What do you want to change?

What database engines need to be changed?

What programming language backends need to be changed?

Activity

nussjustin commented on Sep 6, 2023

rpstw commented on Sep 13, 2023

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

[proposal] `:map key=somefield` query annotation #2353