diff --git a/lib/Pear/LocalLoop/Controller/Api/Categories.pm b/lib/Pear/LocalLoop/Controller/Api/Categories.pm
index 9913f42..95f9db5 100644
--- a/lib/Pear/LocalLoop/Controller/Api/Categories.pm
+++ b/lib/Pear/LocalLoop/Controller/Api/Categories.pm
@@ -43,7 +43,7 @@ sub post_category_list {
   for my $cat_trans ( $month_transaction_category_rs->all ) {
     my $quantised = $c->db_datetime_parser->parse_datetime($cat_trans->get_column('quantised'));
     my $days = $c->format_iso_date( $quantised ) || 0;
-    my $category = $cat_trans->get_column('category_id') || 0;
+    my $category = $cat_trans->get_column('category_id') || undef;
     my $value = ($cat_trans->get_column('value') || 0) / 100000;
     $data->{categories}->{$days} = [] unless exists $data->{categories}->{$days};
     push @{ $data->{categories}->{$days} }, {
diff --git a/lib/Pear/LocalLoop/Controller/Api/Transactions.pm b/lib/Pear/LocalLoop/Controller/Api/Transactions.pm
index a2458d6..e5bbc94 100644
--- a/lib/Pear/LocalLoop/Controller/Api/Transactions.pm
+++ b/lib/Pear/LocalLoop/Controller/Api/Transactions.pm
@@ -42,7 +42,7 @@ sub post_transaction_list_purchases {
       purchase_time => $c->format_iso_datetime($_->purchase_time),
     }} $transactions->all
   );
-  
+
   my @recurring_transaction_list = (
     map {{
       id => $_->id,
@@ -51,7 +51,7 @@ sub post_transaction_list_purchases {
       start_time => $c->format_iso_datetime($_->start_time),
       last_updated => $c->format_iso_datetime($_->last_updated) || undef,
       essential => $_->essential,
-      category => $_->category_id,
+      category => $_->category_id || 0,
       recurring_period => $_->recurring_period,
     }} $recurring_transactions->all
   );
diff --git a/lib/Pear/LocalLoop/Controller/Api/Upload.pm b/lib/Pear/LocalLoop/Controller/Api/Upload.pm
index dea1f10..31fa234 100644
--- a/lib/Pear/LocalLoop/Controller/Api/Upload.pm
+++ b/lib/Pear/LocalLoop/Controller/Api/Upload.pm
@@ -249,16 +249,15 @@ sub post_category {
   #   push @{ $categories->{ ids } }, $_->get_column('id');
   #   push @{ $categories->{ names } }, $_->get_column('name');
   # }
-  my @category_list = (
-    map {{
-      id => $_->id,
-      name => $_->name,
-    }} $category_rs->all
+  my %category_list = (
+    map {
+      $_->id => $_->name,
+    } $category_rs->all
   );
 
   return $self->render( json => {
     success => Mojo::JSON->true,
-    categories => \@category_list,
+    categories => \%category_list,
   });
 }