Add an attachments ListModel to Bill objects

We need to use various workaround as:
- u1db load models in ListModel and any array property (like attachments) are
  transformed in a ListModel
- however, we can't store directly a ListModel (containing ModelObject) to u1db
  as it's transformed as null in the sqlite lite database

splitthebill/components/Bill.qml

@@ -2,7 +2,7 @@ import QtQuick 2.4
 
 import "../tools.js" as Tools
 
-QtObject {
+Item {
     id: self
 
     property string billId
@@ -13,9 +13,12 @@ QtObject {
     property int numTotalPeople
     property int numSharePeople
     property string comments
+    // we use directly a ListModel as a list of Strings is automatically transtyped as such by any attached property
+    // to a model
+    property ListModel attachments: newListModel.createObject(parent)
 
     property var billSavedProperties: ["billId", "title", "date", "rawBill", "tipShare", "numTotalPeople",
-                                       "numSharePeople", "comments"]
+                                       "numSharePeople", "comments", "attachments"]
 
     readonly property double bill: {
         var value = parseFloat(Tools.normalizeNum(rawBill));
@@ -33,6 +36,10 @@ QtObject {
     readonly property double shareBill: _sharePercent * totalBill
     readonly property string formattedDate: date.toLocaleDateString() + " - " + date.toLocaleTimeString()
 
+    NewListModel {
+        id: newListModel
+    }
+
     /* load from json or dictionary compatible objects */
     // this show that qml property can be accessed with object["name"] or object.name
     function loadFromJson(billJson) {
@@ -49,7 +56,33 @@ QtObject {
         var returnJson = {};
         for (var index in billSavedProperties) {
             var prop = billSavedProperties[index];
-            returnJson[prop] = self[prop];
+            /* WORKAROUND:
+             * assigning a list of anything as a property in a model makes it a QMLListModel. We want for our
+             * Bill object to still have a list of json objects for storing in u1db
+             */
+            if (self[prop].toString().indexOf("QQmlListModel") === 0) {
+                var listResult = [];
+                for (var i = 0; i < self[prop].count; i++) {
+                    var elem = self[prop].get(i);
+                    var jsonToStore = {};
+                    /*
+                     * transform a ModelObject to json:
+                     * - we can't store in u1db a ModelObject directly, it will store null
+                     * - there is no trivial function to achieve it (so having to parse it after stringifying it)
+                     * - we want to be flexible and not knowing in advance the properties that can get out of it
+                     */
+                    var jsonElem = JSON.parse(JSON.stringify(elem));
+                    for (var propElem in jsonElem) {
+                        // we don't store the objectName
+                        if (propElem === "objectName")
+                            continue;
+                        jsonToStore[propElem] = jsonElem[propElem];
+                    }
+                    listResult.push(jsonToStore);
+                }
+                returnJson[prop] = listResult;
+            } else
+                returnJson[prop] = self[prop];
         }
         return returnJson;
     }
@@ -63,5 +96,6 @@ QtObject {
         numTotalPeople = 2;
         numSharePeople = 1;
         comments = "";
+        attachments = newListModel.createObject(parent);
     }
 }

splitthebill/components/BillListItem.qml

@@ -25,6 +25,11 @@ ListItem {
         numSharePeople: model.numSharePeople
         // be future-proof when adding new properties
         comments: model.comments ? model.comments: ""
+        attachments: model.attachments ? model.attachments : newListModel.createObject(parent)
+    }
+
+    NewListModel {
+        id: newListModel
     }
 
     Column {

splitthebill/components/NewListModel.qml

@@ -0,0 +1,7 @@
+import QtQuick 2.4
+
+// this show how to create component dynamically
+Component {
+    ListModel {
+    }
+}

splitthebill/splitthebill.pro

@@ -24,7 +24,8 @@ OTHER_FILES += $${CONF_FILES} \
     pages/SettingsPage.qml \
     components/AppSettings.qml \
     components/ErrorDialog.qml \
-    components/DateTimeDialog.qml
+    components/DateTimeDialog.qml \
+    components/NewListModel.qml
 
 #specify where the qml/js files are installed to
 qml_files.path = /splitthebill