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