Bug 23843: Add mapping to Koha::Acquisition::Fund

This patch adds a to_api_mapping method to the class. This in effect
enables calling ->to_api on the object. The mapping is borrowed from the
API controller. It is not removed from the controller so we are able to
verify (through the tests) that there is no behavior change.
Once this is pushed we need to implement the counter-wise methods and
clean the controllers.
To test:
1. Run:
   $ kshell
  k$ prove t/db_dependent/api/v1/acquisitions_funds.t
=> SUCCESS: Tests pass
2. Apply this patch
3. Repeat (1)
=> SUCCESS: Tests still pass!
4. Sign off :-D

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Koha/Acquisition/Fund.pm

@@ -27,6 +27,35 @@ Koha::Acquisition::Fund object class
 
 =head1 API
 
+=head2 Class methods
+
+=head3 to_api_mapping
+
+This method returns the mapping for representing a Koha::Acquisition::Fund object
+on the API.
+
+=cut
+
+sub to_api_mapping {
+    return {
+        budget_id         => 'fund_id',
+        budget_code       => 'code',
+        budget_name       => 'name',
+        budget_branchcode => 'library_id',
+        budget_amount     => 'total_amount',
+        budget_encumb     => 'warn_at_percentage',
+        budget_expend     => 'warn_at_amount',
+        budget_notes      => 'notes',
+        budget_period_id  => 'budget_id',
+        timestamp         => 'timestamp',
+        budget_owner_id   => 'fund_owner_id',
+        budget_permission => 'fund_access',
+        sort1_authcat     => 'statistic1_auth_value_category',
+        sort2_authcat     => 'statistic2_auth_value_category',
+        budget_parent_id  => 'parent_fund_id',
+    };
+}
+
 =head2 Internal methods
 
 =head3 _type

Koha/REST/V1/Acquisitions/Funds.pm

@@ -56,10 +56,11 @@ sub list_funds {
     }
 
     return try {
-        my @funds = Koha::Acquisition::Funds->search($filter);
-        @funds = map { _to_api($_->TO_JSON) } @funds;
-        return $c->render( status  => 200,
-                           openapi =>  \@funds);
+        my $funds = Koha::Acquisition::Funds->search($filter);
+        return $c->render(
+            status  => 200,
+            openapi => $funds->to_api
+        );
     }
     catch {
         if ( $_->isa('DBIx::Class::Exception') ) {

api/v1/swagger/definitions/fund.json

@@ -81,6 +81,10 @@
       ],
       "description": "Level of permission for this fund (1: owner, 2: owner, users and library, 3: owner and users)"
     },
+    "parent_fund_id": {
+        "type": [ "integer", "null" ],
+        "description": "Internal identifier for parent fund"
+    },
     "statistic1_auth_value_category": {
       "type": [
         "string",