Files
genqlient/internal/testutil/types.go
T
Ben Kraft f4c981031e Allow genqlient types to be marshaled safely (#120)
## Summary:
When genqlient generates output types, it generates whatever code is
necessary to unmarshal them.  Conversely, when it generates input types,
it generates whatever code is necessary to marshal.  This is all that's
needed for genqlient itself: it never needs to marshal output types or
unmarshal input types.

But maybe you do!  (For example, to put the responses in a cache, which
is the use case that @csilvers hit at Khan, although there are others
one can imagine.)  While we can't support every serialization format you
might want (at least not without adding plugins or some such), it's not
unreasonable to expect that since genqlient can read JSON, it can write
it too.  Sadly, in the past this was not true for types requiring custom
unmarshaling logic, for several reasons.

In this commit I implement logic to always write both marshalers and
unmarshalers whenever they're needed to be able to correctly round-trip
the types, even though genqlient doesn't do so.  I wasn't starting from
scratch, since of course we already write both marshalers and
unmarshalers in some cases.  But this ended up requiring surprisingly
large changes on the marshaling side, mostly to correctly support
embedding (which we use for named fragments).

Specifically, as the comments in `types.go` discuss, the most difficult
issue is spreads with duplicate fields, which translate to Go embedded
fields which end up hidden from the json-marshaler.  Ultimately, I had
to do things quite differently from unmarshaling, and essentially
flatten the type when we write marshaler.  But in the end it's not so
ugly -- indeed arguably it's cleaner!  Mainly it's just different.

One thing to note is that we do marshal `__typename` based on
what we know about the types; users need not fill it in (and if they
do we'll ignore it).  This seemed to me to be a better UX, and
didn't add much complexity.

In general, I begin to wonder whether using `encoding/json` at all is
really right for genqlient: we're doing a lot of work to appease it,
despite knowing what our types look like.  I think it would still be a
significant increase in lines of code to roll our own, but that code
would perhaps be simpler, and would surely be faster (although if we
just want the speed gains we could use another JSON-generator library,
see also #47).  Anyway, something to think about in the future.

## Test plan:
make tesc


Author: benjaminjkraft

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

Required Reviewers: 

Approved By: StevenACoffman, dnerdy

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/120
2021-09-29 10:30:43 -07:00

52 lines
1.2 KiB
Go

package testutil
import (
"context"
"time"
"github.com/Khan/genqlient/graphql"
)
type ID string
type Pokemon struct {
Species string `json:"species"`
Level int `json:"level"`
}
func (p Pokemon) Battle(q Pokemon) bool {
return p.Level > q.Level
}
type MyContext interface {
context.Context
MyMethod()
}
func GetClientFromNowhere() (graphql.Client, error) { return nil, nil }
func GetClientFromContext(ctx context.Context) (graphql.Client, error) { return nil, nil }
func GetClientFromMyContext(ctx MyContext) (graphql.Client, error) { return nil, nil }
const dateFormat = "2006-01-02"
func MarshalDate(t *time.Time) ([]byte, error) {
// nil should never happen but we might as well check. zero-time does
// happen because omitempty doesn't consider it zero; we'd prefer to write
// null than "0001-01-01".
//
// (I mean, we're tests. Who cares! But we may as well try to match what
// prod code would want.)
if t == nil || t.IsZero() {
return []byte("null"), nil
}
return []byte(`"` + t.Format(dateFormat) + `"`), nil
}
func UnmarshalDate(b []byte, t *time.Time) error {
// (modified from time.Time.UnmarshalJSON)
var err error
*t, err = time.Parse(`"`+dateFormat+`"`, string(b))
return err
}