this changes makes api_field_* variables lazy

api_field_types and api_field_names rely on values from the
Bugzilla->fields definition. This in turn requires checking the schema
of the bugs table at run time. That means trying to access these when a
database is not configured, or before schema migrations have happened is
an error.

This changes those variables to hold functions (sub refs) that are
comptued when called. The help performance not degrade, we make use of
the Bugzilla::request_cache to only re-compute this once per request.

Author: dylanwh

Bugzilla/WebService/Bug.pm

@@ -110,16 +110,23 @@ use constant ATTACHMENT_MAPPED_RETURNS => {
   mimetype    => 'content_type',
 };
 
-our %api_field_types = (
-  %{{map { $_ => 'double' } Bugzilla::Bug::NUMERIC_COLUMNS()}},
-  %{{map { $_ => 'dateTime' } Bugzilla::Bug::DATE_COLUMNS()}},
-);
+our $api_field_types = sub {
+  Bugzilla::request_cache->{api_field_types} ||= {
+    %{{map { $_ => 'double' } Bugzilla::Bug::NUMERIC_COLUMNS()}},
+    %{{map { $_ => 'dateTime' } Bugzilla::Bug::DATE_COLUMNS()}},
+  };
+};
 
-our %api_field_names = reverse %{Bugzilla::Bug::FIELD_MAP()};
+our $api_field_names = sub {
+  Bugzilla::request_cache->{api_field_types} ||= do {
+    my $tmp = {reverse %{Bugzilla::Bug::FIELD_MAP()}};
 
-# This doesn't normally belong in FIELD_MAP, but we do want to translate
-# "bug_group" back into "groups".
-$api_field_names{'bug_group'} = 'groups';
+    # This doesn't normally belong in FIELD_MAP, but we do want to translate
+    # "bug_group" back into "groups".
+    $tmp->{'bug_group'} = 'groups';
+    $tmp;
+  };
+};
 
 ######################################################
 # Add aliases here for old method name compatibility #
@@ -841,9 +848,10 @@ sub update {
     }
 
     my %changes = %{$all_changes{$bug->id}};
+    my $names   = $api_field_names->();
     foreach my $field (keys %changes) {
       my $change    = $changes{$field};
-      my $api_field = $api_field_names{$field} || $field;
+      my $api_field = $names->{$field} || $field;
 
       # We normalize undef to an empty string, so that the API
       # stays consistent for things like Deadline that can become
@@ -1760,8 +1768,8 @@ sub _changeset_to_hash {
 
   foreach my $change (@{$changeset->{changes}}) {
     my $field_name     = delete $change->{fieldname};
-    my $api_field_type = $api_field_types{$field_name} || 'string';
-    my $api_field_name = $api_field_names{$field_name} || $field_name;
+    my $api_field_type = $api_field_types->()->{$field_name} || 'string';
+    my $api_field_name = $api_field_names->()->{$field_name} || $field_name;
     my $attach_id      = delete $change->{attachid};
     my $comment        = delete $change->{comment};