generalized DB engine to support multiple types (upload+form)

common/types.go

@@ -17,6 +17,11 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 package common
 
+import (
+	"encoding/json"
+	"fmt"
+)
+
 // used to return to the api client
 type Result struct {
 	Success bool   `json:"success"`
@@ -24,6 +29,12 @@ type Result struct {
 	Code    int    `json:"code"`
 }
 
+// upload or form structs
+type Dbentry interface {
+	Getcontext(j []byte) (string, error)
+	Marshal() ([]byte, error)
+}
+
 type Upload struct {
 	Id       string    `json:"id"`
 	Expire   string    `json:"expire"`
@@ -35,9 +46,96 @@ type Upload struct {
 }
 
 // this one is also used for marshalling to the client
-type Uploads struct {
-	Entries []*Upload `json:"uploads"`
+type Response struct {
+	Uploads []*Upload `json:"uploads"`
+	Forms   []*Form   `json:"forms"`
 
 	// integrate the Result struct so we can signal success
 	Result
 }
+
+type Form struct {
+	Id          string    `json:"id"`
+	Expire      string    `json:"expire"`
+	Description string    `json:"description"`
+	Created     Timestamp `json:"uploaded"`
+	Context     string    `json:"context"`
+	Url         string    `json:"url"`
+}
+
+const (
+	TypeUpload = iota
+	TypeForm
+)
+
+/*
+   implement Dbentry interface
+*/
+func (upload Upload) Getcontext(j []byte) (string, error) {
+	if err := json.Unmarshal(j, &upload); err != nil {
+		return "", fmt.Errorf("unable to unmarshal json: %s", err)
+	}
+
+	return upload.Context, nil
+}
+
+func (form Form) Getcontext(j []byte) (string, error) {
+	if err := json.Unmarshal(j, &form); err != nil {
+		return "", fmt.Errorf("unable to unmarshal json: %s", err)
+	}
+
+	return form.Context, nil
+}
+
+func (upload Upload) Marshal() ([]byte, error) {
+	jsonentry, err := json.Marshal(upload)
+	if err != nil {
+		return nil, fmt.Errorf("json marshalling failure: %s", err)
+	}
+
+	return jsonentry, nil
+}
+
+func (form Form) Marshal() ([]byte, error) {
+	jsonentry, err := json.Marshal(form)
+	if err != nil {
+		return nil, fmt.Errorf("json marshalling failure: %s", err)
+	}
+
+	return jsonentry, nil
+}
+
+/*
+   Extract  context, whatever  kind entry  is,  but we  don't know  in
+   advance, only  after unmarshalling.  So try  Upload first,  if that
+   fails, try Form.
+*/
+func GetContext(j []byte) (string, error) {
+	upload := &Upload{}
+	entryContext, err := upload.Getcontext(j)
+	if err != nil {
+		form := &Form{}
+		entryContext, err = form.Getcontext(j)
+		if err != nil {
+			return "", fmt.Errorf("unable to unmarshal json: %s", err)
+		}
+	}
+
+	return entryContext, nil
+}
+
+func Unmarshal(j []byte, t int) (Dbentry, error) {
+	if t == TypeUpload {
+		upload := &Upload{}
+		if err := json.Unmarshal(j, &upload); err != nil {
+			return upload, fmt.Errorf("unable to unmarshal json: %s", err)
+		}
+		return upload, nil
+	} else {
+		form := &Form{}
+		if err := json.Unmarshal(j, &form); err != nil {
+			return form, fmt.Errorf("unable to unmarshal json: %s", err)
+		}
+		return form, nil
+	}
+}