Files
genqlient/generate/testdata/snapshots/TestGenerate-CustomMarshal.graphql-CustomMarshal.graphql.go
T
Ben KraftandGitHub 65c3e20ee6 Fix bugs relating to optional fields with custom (un)marshalers (#116)
## Summary:
There were a few bugs here, one of which Craig came across when pulling
the custom-unmarshaler change into webapp:
1. If you have an optional field with a custom unmarshaler, and the
   server omits the field from the response entirely (i.e. does not
   write `"myField": null`), we would still call your unmarshaler with
   an input of `[]byte(nil)`.  This is just wrong; it's our job to do
   the nil-check.  (This is the one Craig found; in practice gqlgen
   servers do not do this and I think the spec says not to although it's
   a bit fuzzy on the matter of serialization.  But in practice we have
   mocks that do it -- for required fields even! -- and it seems better
   to handle it than pass you data on which you'll probably err or even
   panic.)
2. If you have an optional field with a custom unmarshaler, and the
   server returns an explicit null (i.e. `"myField": null`), we would
   call your unmarshaler with `[]byte("null")`.  In principle the intent
   was you're supposed to implement that, as [`json.Unmarshaler`
   advises][1].  But (a) I forgot to document that, and (b) in practice
   `json.Unmarshal` [does *not* call you in that case][2], i.e. its
   advice is unnecessary.  So I think it's better for us to just match
   it, and not call you.  (And in that case I see no reason to bother
   documenting the advice.)
3. If you have an optional, `pointer: true` field with a custom
   marshaler, the reverse of (2) applies: if the pointer is nil, we
   shouldn't really call you.  (Indeed if you were a real
   `json.Marshaler` with a value-method rather than a pointer-method,
   trying to call you might panic!)  Note we don't need to explicitly
   write "null"; we just leave the `json.RawMessage` as nil, and
   `json.Marshal` [handles that][3].
4. We handle interface types effectively the same as custom
   unmarshalers, just we generate the unmarshaler.  So if you have an
   optional field with interface type, (1) would also apply there; our
   generated unmarshaler returns an error in this case.
5. While (2) doesn't apply to such optional interface fields (because we
   do the customary `if string(b) == "null"` check -- this I at least
   thought to test), if you set `pointer: true` on the field, we would
   still call the unmarshaler on the value, and it would no-op, but only
   *after* we initialized the pointer.  Put more simply, we'd return a
   non-nil pointer to nil interface, rather than a nil pointer; this is
   wrong since the whole point of `pointer: true` is you only get a
   non-nil pointer if your value is nil!  Of course, in practice there's
   little reason to use `pointer: true` on interface fields, and indeed
   this stuff gets so confusing my test was even wrong.

In this commit I fix all the bugs, by adding appropriate nil-checks to
wrap the unmarshaler-calls.  The templates are, as always, a bit
confusing, but the generated code makes it clear what changed.

Note we'll want to land this before cutting a release with custom
marshaler/unmarshaler support, because the first three bugs are
potentially quite noticeable.  (The latter two are in `v0.1.0`, but
presumably quite rare.)

[1]: https://pkg.go.dev/encoding/json#Unmarshaler
[2]: https://play.golang.org/p/Pw6zNN8trGO
[3]: https://play.golang.org/p/crTfnT7ePte

Issue: https://phabricator.khanacademy.org/D74453#inline-558571

## Test plan:
make tesc


Author: benjaminjkraft

Reviewers: csilvers, StevenACoffman, benjaminjkraft, aberkan, dnerdy, jvoll, mahtabsabet, MiguelCastillo

Required Reviewers: 

Approved By: csilvers, StevenACoffman

Checks:  Test (1.17),  Test (1.16),  Test (1.15),  Test (1.14),  Lint,  Test (1.17),  Test (1.16),  Test (1.15),  Test (1.14),  Lint

Pull Request URL: https://github.com/Khan/genqlient/pull/116
2021-09-27 20:35:39 -07:00

121 lines
2.3 KiB
Go

package test
// Code generated by github.com/Khan/genqlient, DO NOT EDIT.
import (
"encoding/json"
"fmt"
"time"
"github.com/Khan/genqlient/graphql"
"github.com/Khan/genqlient/internal/testutil"
)
// CustomMarshalResponse is returned by CustomMarshal on success.
type CustomMarshalResponse struct {
UsersBornOn []CustomMarshalUsersBornOnUser `json:"usersBornOn"`
}
// CustomMarshalUsersBornOnUser includes the requested fields of the GraphQL type User.
// The GraphQL type's documentation follows.
//
// A User is a user!
type CustomMarshalUsersBornOnUser struct {
// id is the user's ID.
//
// It is stable, unique, and opaque, like all good IDs.
Id testutil.ID `json:"id"`
Birthdate time.Time `json:"-"`
}
func (v *CustomMarshalUsersBornOnUser) UnmarshalJSON(b []byte) error {
if string(b) == "null" {
return nil
}
var firstPass struct {
*CustomMarshalUsersBornOnUser
Birthdate json.RawMessage `json:"birthdate"`
graphql.NoUnmarshalJSON
}
firstPass.CustomMarshalUsersBornOnUser = v
err := json.Unmarshal(b, &firstPass)
if err != nil {
return err
}
{
dst := &v.Birthdate
src := firstPass.Birthdate
if len(src) != 0 && string(src) != "null" {
err = testutil.UnmarshalDate(
src, dst)
if err != nil {
return fmt.Errorf(
"Unable to unmarshal CustomMarshalUsersBornOnUser.Birthdate: %w", err)
}
}
}
return nil
}
// __CustomMarshalInput is used internally by genqlient
type __CustomMarshalInput struct {
Date time.Time `json:"-"`
}
func (v *__CustomMarshalInput) MarshalJSON() ([]byte, error) {
var fullObject struct {
*__CustomMarshalInput
Date json.RawMessage `json:"date"`
graphql.NoMarshalJSON
}
fullObject.__CustomMarshalInput = v
{
dst := &fullObject.Date
src := v.Date
var err error
*dst, err = testutil.MarshalDate(
&src)
if err != nil {
return nil, fmt.Errorf(
"Unable to marshal __CustomMarshalInput.Date: %w", err)
}
}
return json.Marshal(&fullObject)
}
func CustomMarshal(
client graphql.Client,
date time.Time,
) (*CustomMarshalResponse, error) {
__input := __CustomMarshalInput{
Date: date,
}
var err error
var retval CustomMarshalResponse
err = client.MakeRequest(
nil,
"CustomMarshal",
`
query CustomMarshal ($date: Date!) {
usersBornOn(date: $date) {
id
birthdate
}
}
`,
&retval,
&__input,
)
return &retval, err
}