mod id.Extract to return an error if no valid id is found

* add function Factory.QIDFromQIHOT (format)

format/factory.go

@@ -88,6 +88,8 @@ type Factory interface {
 
 	// NewMetadataCodec returns the codec for serializing metadata
 	NewMetadataCodec() codecs.MultiCodec
+
+	QIDFromQIHOT(qihot string) (QID, error)
 }
 
 // NewFactory creates a new format factory.
@@ -277,3 +279,26 @@ func (f *factory) NewMetadataCodec() codecs.MultiCodec {
 func (f *factory) ParseQSpaceID(s string) (QSpaceID, error) {
 	return id.QSpace.FromString(s)
 }
+
+// QIDFromQIHOT retrieves the content ID in the given hash write token and qid.
+// The function expects a content hash, a content write token or a content ID.
+func (f *factory) QIDFromQIHOT(qihot string) (QID, error) {
+	e := errors.Template("QIDFromQIHOT", errors.K.Invalid, "qihot", qihot)
+	var qid id.ID
+	qh, err := f.ParseQHash(qihot)
+	if err != nil {
+		var qwt QWriteToken
+		qwt, err = f.ParseQWriteToken(qihot)
+		if err != nil {
+			qid, err = f.ParseQID(qihot)
+		} else {
+			qid = qwt.QID
+		}
+	} else {
+		qid = qh.ID
+	}
+	if err != nil {
+		return nil, e("reason", "not a qhash, a token or a qid", err)
+	}
+	return qid, nil
+}

format/id/util.go

@@ -1,23 +1,32 @@
 package id
 
-// Extract parses each of the provided strings as an ID. Empty strings are ignored, parsing errors are returned. The
-// first ID that is compatible with the provided target code is returned. If an ID has an embedded ID that matches, it
-// is returned.
+import (
+	"strings"
+
+	"github.com/eluv-io/errors-go"
+)
+
+// Extract parses each of the provided strings as an ID. Empty strings are ignored, parsing errors are returned.
+// The first ID that is compatible with the provided target code and is valid is returned. If an ID has an embedded
+// valid ID that matches, it is returned.
+// If no valid ID is found, an error is returned.
 func Extract(target Code, ids ...string) (ID, error) {
 	for _, candidate := range ids {
 		if candidate != "" {
 			cid, err := Parse(candidate)
 			if err != nil {
 				return nil, err
 			}
-			if cid.Code().IsCompatible(target) {
+			if cid.Code().IsCompatible(target) && cid.IsValid() {
 				return cid, nil
 			}
 			cid = Decompose(cid).Embedded()
-			if cid.Code().IsCompatible(target) {
+			if cid.Code().IsCompatible(target) && cid.IsValid() {
 				return cid, nil
 			}
 		}
 	}
-	return nil, nil
+	return nil, errors.E("Extract", errors.K.Invalid,
+		"reason", "no valid id found",
+		"ids", strings.Join(ids, ","))
 }

format/id/util_test.go

@@ -28,28 +28,29 @@ func TestExtract(t *testing.T) {
 		want    id.ID
 		wantErr bool
 	}{
-		{id.Tenant, nil, nil, false},
-		{id.Tenant, []string{""}, nil, false},
+		{id.Tenant, nil, nil, true},
+		{id.Tenant, []string{""}, nil, true},
 		{id.Tenant, []string{tid.String()}, tid, false},
 		{id.Tenant, []string{"", qid.String(), lid.String(), tid.String()}, tid, false},
 		{id.Tenant, []string{tqid.String()}, tid, false},
 		{id.Tenant, []string{tlid.String()}, tid, false},
-		{id.Tenant, []string{einv.String()}, id.NewID(id.Tenant, nil), false},
-		{id.Tenant, []string{einv2.String()}, id.NewID(id.Tenant, nil), false},
+		{id.Tenant, []string{einv.String()}, id.NewID(id.Tenant, nil), true},
+		{id.Tenant, []string{einv2.String()}, id.NewID(id.Tenant, nil), true},
 		{id.Q, []string{tqid.String()}, tqid.ID(), false},
 		{id.QLib, []string{tlid.String()}, tlid.ID(), false},
 		{id.Tenant, []string{"no ID!"}, nil, true},
 		{id.Tenant, []string{"", qid.String(), "no ID!"}, nil, true},
-		{id.Tenant, []string{einv3.String()}, id.NewID(id.Tenant, nil), false},
+		{id.Tenant, []string{einv3.String()}, id.NewID(id.Tenant, nil), true},
 	}
 	for i, tt := range tests {
 		t.Run(fmt.Sprint(tt.target, " ", strings.Join(tt.ids, "|")), func(t *testing.T) {
 			got, err := id.Extract(tt.target, tt.ids...)
-			require.Equal(t, tt.want, got, "case %d", i)
 			if tt.wantErr {
 				require.Error(t, err, "case %d", i)
 			} else {
+				require.Equal(t, tt.want, got, "case %d", i)
 				require.NoError(t, err, "case %d", i)
+				require.True(t, got.IsValid(), "case %d", i)
 			}
 		})
 	}