Added image as an allowed custom theme setting type

refs https://github.com/TryGhost/Team/issues/1107

- updated schema validation to allow `'image'` through as a known setting type now that Admin has support
- added transformation of setting values for `'image'` types because they will be URLs and should be stored with `__GHOST_URL__`

core/server/data/schema/schema.js

@@ -681,7 +681,8 @@ module.exports = {
                     'select',
                     'boolean',
                     'color',
-                    'text'
+                    'text',
+                    'image'
                 ]]
             }
         },

core/server/models/custom-theme-setting.js

@@ -1,5 +1,6 @@
 const _ = require('lodash');
 const ghostBookshelf = require('./base');
+const urlUtils = require('../../shared/url-utils');
 
 const CustomThemeSetting = ghostBookshelf.Model.extend({
     tableName: 'custom_theme_settings',
@@ -18,6 +19,12 @@ const CustomThemeSetting = ghostBookshelf.Model.extend({
             attrs.value = JSON.parse(attrs.value);
         }
 
+        // transform URLs to absolute for image settings
+        if (settingType === 'image' && attrs.value) {
+            console.log('.parse', attrs.value, urlUtils.transformReadyToAbsolute(attrs.value));
+            attrs.value = urlUtils.transformReadyToAbsolute(attrs.value);
+        }
+
         return attrs;
     },
 
@@ -41,6 +48,14 @@ const CustomThemeSetting = ghostBookshelf.Model.extend({
             }
         }
 
+        return attrs;
+    },
+
+    formatOnWrite(attrs) {
+        if (attrs.type === 'image' && attrs.value) {
+            attrs.value = urlUtils.toTransformReady(attrs.value);
+        }
+
         return attrs;
     }
 });

test/unit/server/models/custom-theme-setting.test.js

@@ -30,6 +30,9 @@ describe('Unit: models/custom-theme-setting', function () {
 
             returns = setting.parse({theme: 'test', key: 'something', value: 'null', type: 'select'});
             should.equal(returns.value, 'null');
+
+            returns = setting.parse({theme: 'test', key: 'something', value: '__GHOST_URL__/assets/image.jpg', type: 'image'});
+            should.equal(returns.value, 'http://127.0.0.1:2369/assets/image.jpg');
         });
     });
 
@@ -49,5 +52,12 @@ describe('Unit: models/custom-theme-setting', function () {
             returns = setting.format({theme: 'test', key: 'dark_mode', value: 'true', type: 'boolean'});
             should.equal(returns.value, 'true');
         });
+
+        it('transforms urls when persisting to db', function () {
+            const setting = models.CustomThemeSetting.forge();
+
+            let returns = setting.formatOnWrite({theme: 'test', key: 'something', value: '/assets/image.jpg', type: 'image'});
+            should.equal(returns.value, '__GHOST_URL__/assets/image.jpg');
+        });
     });
 });