Automap not struct type to struct with one field and vice versa (probably)

[a1eks3y]

Is your feature request related to a problem? Please describe.
Currently, the library does not support automatically mapping a non-struct type to a struct with a single field of the same type. This is especially inconvenient when working with protobuf types, where primitive values are commonly wrapped, such as with optional string Value = 1.

Describe the solution you'd like
Automatically support mapping between primitive types and structs with a single field of the same type. For example, allow mapping between map[string]*string and map[string]StringPtr when StringPtr wraps a *string.

Describe alternatives you've considered
:extend with custom mapping function

Please 👍 this issue if you like this functionality. If you have a specific use-case in mind, feel free to comment it.

[jmattheis]

Could you give an example how to generate the wrapper struct. For me protoc doesn't create this.

message Event {
  string content = 1;
  int32 priority = 2;
  optional bool hidden = 3;
}

and this generate to

type Event struct {
	state         protoimpl.MessageState `protogen:"open.v1"`
	Content       string                 `protobuf:"bytes,1,opt,name=content,proto3" json:"content,omitempty"`
	Priority      int32                  `protobuf:"varint,2,opt,name=priority,proto3" json:"priority,omitempty"`
	Hidden        *bool                  `protobuf:"varint,3,opt,name=hidden,proto3,oneof" json:"hidden,omitempty"`
	unknownFields protoimpl.UnknownFields
	sizeCache     protoimpl.SizeCache
}

with

$ protoc -I=./ --go_out=./ ./event.proto

[a1eks3y]

Try something like this:

message Map {
  message OptionalString {
    optional string value = 1;
  }

  map<string, OptionalString> map = 1;
}

[a1eks3y]

@jmattheis in this example there is no way to add optional string in map value directly, so you need to add "wrapper message" which you can use as a map value

[jmattheis]

Yeah thanks for the example. Is this really a common pattern. Seems pretty useless to do this. I'm not against supporting this, but I'd wait for some feedback from other users.

[udzin]

it is also useful for using Optional wrapper for pointers

*sting => Option[string]
*int => Option[int]
*struct => Option[struct]

and vice-versa

Option[string] => *sting