fix: use custom marshaler for n_epochs

fine_tuning_job.go

@@ -2,6 +2,7 @@ package openai
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -23,8 +24,40 @@ type FineTuningJob struct {
 	TrainedTokens   int             `json:"trained_tokens"`
 }
 
+type HyperparameterNEpochs struct {
+	IntValue    *int    `json:"-"`
+	StringValue *string `json:"-"`
+}
+
+func (h *HyperparameterNEpochs) UnmarshalJSON(data []byte) error {
+	var intValue int
+	var stringValue string
+
+	if err := json.Unmarshal(data, &intValue); err == nil {
+		h.IntValue = &intValue
+		return nil
+	}
+
+	if err := json.Unmarshal(data, &stringValue); err != nil {
+		return err
+	}
+
+	h.StringValue = &stringValue
+	return nil
+}
+
+func (h *HyperparameterNEpochs) MarshalJSON() ([]byte, error) {
+	if h.IntValue != nil {
+		return json.Marshal(*h.IntValue)
+	} else if h.StringValue != nil {
+		return json.Marshal(*h.StringValue)
+	}
+
+	return nil, fmt.Errorf("invalid hyperparameter n_epochs")
+}
+
 type Hyperparameters struct {
-	Epochs int `json:"n_epochs"`
+	Epochs *HyperparameterNEpochs `json:"n_epochs,omitempty"`
 }
 
 type FineTuningJobRequest struct {

fine_tuning_job_test.go

@@ -21,8 +21,27 @@ func TestFineTuningJob(t *testing.T) {
 	server.RegisterHandler(
 		"/v1/fine_tuning/jobs",
 		func(w http.ResponseWriter, r *http.Request) {
-			var resBytes []byte
-			resBytes, _ = json.Marshal(FineTuningJob{})
+			nEpochs := "auto"
+			resBytes, _ := json.Marshal(FineTuningJob{
+				Object:         "fine_tuning.job",
+				ID:             testFineTuninigJobID,
+				Model:          "davinci-002",
+				CreatedAt:      1692661014,
+				FinishedAt:     1692661190,
+				FineTunedModel: "ft:davinci-002:my-org:custom_suffix:7q8mpxmy",
+				OrganizationID: "org-123",
+				ResultFiles:    []string{"file-abc123"},
+				Status:         "succeeded",
+				ValidationFile: "",
+				TrainingFile:   "file-abc123",
+				Hyperparameters: Hyperparameters{
+					Epochs: &HyperparameterNEpochs{
+						IntValue:    nil,
+						StringValue: &nEpochs,
+					},
+				},
+				TrainedTokens: 5768,
+			})
 			fmt.Fprintln(w, string(resBytes))
 		},
 	)