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Add ErrKeyExists on kv.Create #1135

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merged 1 commit into from Nov 16, 2022
Merged

Add ErrKeyExists on kv.Create #1135

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9 changes: 9 additions & 0 deletions kv.go
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Expand Up @@ -297,6 +297,7 @@ var (
ErrKeyDeleted = errors.New("nats: key was deleted")
ErrHistoryToLarge = errors.New("nats: history limited to a max of 64")
ErrNoKeysFound = errors.New("nats: no keys found")
ErrKeyExists = errors.New("nats: key exists")
)

const (
Expand Down Expand Up @@ -629,6 +630,14 @@ func (kv *kvs) Create(key string, value []byte) (revision uint64, err error) {
return kv.Update(key, value, e.Revision())
}

// Check if the expected last subject sequence is not zero which implies
// the key already exists.
if aerr, ok := err.(*APIError); ok {
if aerr.ErrorCode == 10071 {
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Let me know if there is a better way to identify this particular error type.

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maybe add it as one of the constants here: https://github.com/nats-io/nats.go/blob/main/jserrors.go#L112
so that it represents this error from the server:
https://github.com/nats-io/nats-server/blob/e42260cc80f793006ef7f90cc91ede26fe14073f/server/jetstream_errors_generated.go#L536

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something that we started doing in the nats.go client is to move these codes into jserrors.go:
https://github.com/nats-io/nats.go/blob/main/jserrors.go#L121

then to make it compatible with errors.Is defining something like:

ErrWrongLastSequence JetStreamError = &jsError{apiErr: &APIError{ErrorCode: JSErrStreamWrongLastSequence}}

then this check would become:

if errors.Is(err, ErrWrongLastSequence) {
 return ErrKeyExists
}

What I think might be helpful eventually is to have something like another KeyValueError type that embeds the original JS APIError to be able to inspect the original JS API Error which resulted into the KeyValueError by using errors.As.

return 0, ErrKeyExists
}
}

return 0, err
}

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23 changes: 23 additions & 0 deletions kv_test.go
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Expand Up @@ -203,3 +203,26 @@ func TestKeyValueMirrorDirectGet(t *testing.T) {
}
}
}

func TestKeyValueCreate(t *testing.T) {
s := RunBasicJetStreamServer()
defer shutdownJSServerAndRemoveStorage(t, s)

nc, js := jsClient(t, s)
defer nc.Close()

kv, err := js.CreateKeyValue(&KeyValueConfig{Bucket: "TEST"})
if err != nil {
t.Fatalf("Error creating kv: %v", err)
}

_, err = kv.Create("key", []byte("1"))
if err != nil {
t.Fatalf("Error creating key: %v", err)
}

_, err = kv.Create("key", []byte("1"))
if err != ErrKeyExists {
t.Fatalf("Expected ErrKeyExists, got: %v", err)
}
}