2 files changed, 31 insertions, 0 deletions
diff --git a/srv/src/post/post.go b/srv/src/post/post.go
index bf851af..29a984f 100644
--- a/srv/src/post/post.go
+++ b/srv/src/post/post.go
@@ -68,6 +68,9 @@ type Store interface {
 	// descending, or empty slice.
 	GetByTag(tag string) ([]StoredPost, error)
 
+	// GetTags returns all tags which have at least one Post using them.
+	GetTags() ([]string, error)
+
 	// Delete will delete the StoredPost with the given ID.
 	Delete(id string) error
 }
@@ -340,6 +343,30 @@ func (s *store) GetByTag(tag string) ([]StoredPost, error) {
 	return posts, err
 }
 
+func (s *store) GetTags() ([]string, error) {
+
+	rows, err := s.db.Query(`SELECT tag FROM post_tags GROUP BY tag`)
+	if err != nil {
+		return nil, fmt.Errorf("querying all tags: %w", err)
+	}
+	defer rows.Close()
+
+	var tags []string
+
+	for rows.Next() {
+
+		var tag string
+
+		if err := rows.Scan(&tag); err != nil {
+			return nil, fmt.Errorf("scanning tag: %w", err)
+		}
+
+		tags = append(tags, tag)
+	}
+
+	return tags, nil
+}
+
 func (s *store) Delete(id string) error {
 
 	tx, err := s.db.Begin()
diff --git a/srv/src/post/post_test.go b/srv/src/post/post_test.go
index 97757e5..b6d8a2e 100644
--- a/srv/src/post/post_test.go
+++ b/srv/src/post/post_test.go
@@ -252,5 +252,9 @@ func TestStore(t *testing.T) {
 		bazPosts, err := h.store.GetByTag("baz")
 		assert.NoError(t, err)
 		assert.Empty(t, bazPosts)
+
+		tags, err := h.store.GetTags()
+		assert.NoError(t, err)
+		assert.ElementsMatch(t, []string{"foo", "bar"}, tags)
 	})
 }