feat(attrib-loader): attribute loader from service

src/js/RAMP/Modules/attributeLoader.js

@@ -0,0 +1,113 @@
+/* global define, console */
+
+/**
+*
+*
+* @module RAMP
+* @submodule AttributeLoader
+*/
+
+//TODO should this be under DataLoader submodule??
+
+/**
+* Attribute Loader class.
+*
+* Handles the extraction of attribute data from map services, and transforms it to standard format
+*
+* ####Imports RAMP Modules:
+* {{#crossLink "EventManager"}}{{/crossLink}}
+* {{#crossLink "GlobalStorage"}}{{/crossLink}}
+*
+* @class AttributeLoader
+* @static
+* @uses dojo/topic
+* @uses dojo/Deferred
+* @uses dojo/request/script
+*/
+
+define([
+/* Dojo */
+"dojo/topic", "dojo/request/script", "dojo/Deferred",
+
+/* RAMP */
+"ramp/eventManager", "ramp/globalStorage"],
+
+    function (
+    /* Dojo */
+    topic, script, Deferred,
+
+    /* RAMP */
+    EventManager, GlobalStorage) {
+        "use strict";
+
+        /**
+        * Will download the attribute data for a layer.
+        *
+        * @method loadAttributeData
+        * @private
+        * @param  {String} layerId id of the layer
+        * @param  {String} layerUrl the URL of the layer
+        * @param  {String} layerType type of the layer. should be a value from GlobalStorage.layerType
+        * @param  {Object} [options] additional options for layer item (mostly error messages in this case)
+        */
+        function loadAttributeData(layerId, layerUrl, layerType) {
+            switch (layerType) {
+                case GlobalStorage.layerType.feature:
+
+                    //fetch attributes from feature layer. where 1=1 (all records). outFields * (all attributes). no geometry.
+                    var defService = script.get(layerUrl + '/query', {
+                        query: "where=1%3D1&outFields=*&returnGeometry=false&f=json",
+                        jsonp: "callback"
+                    });
+
+                    defService.then(
+                    function (result) {
+                        //change to standard format and store.
+                        //TODO change if we decide on a non-esri standard format
+                        var attribData = {
+                            layerId: layerId,
+                            features: result.features,
+                            index: {}
+                        };
+
+                        //TODO consider having the following stuff in a different function, that can be called when file based stuff is loaded.
+
+                        //find object id field
+                        result.fields.every(function (elem) {
+                            if (elem.type === 'esriFieldTypeOID') {
+                                attribData.idField = elem.name;
+                                return false; //break the loop
+                            }
+                            return true; //keep looping
+                        });
+
+                        //make parent pointers and a fun index on object id
+                        attribData.features.forEach(function (elem, idx) {
+                            //map object id to index of object in feature array
+                            //use toString, as objectid is integer and will act funny using array notation.
+                            attribData.index[elem.attributes[attribData.idField].toString()] = idx;
+
+                            //pointer back to parent
+                            elem.parent = attribData;
+                        });
+
+                        //TODO store attribData somewhere
+                    },
+                    function (error) {
+                        console.log("Attribute load error : " + error);
+                    });
+
+                    break;
+
+                default:
+                    console.log("Layer type not supported by attribute loader: " + layerType);
+            }
+
+            //TODO do we need to return any sort of promise to indicate when the loading has finished?
+            //TODO should we raise a topic indicating loading has finished (could trigger a grid refresh)
+        }
+
+        return {
+            loadAttributeData: loadAttributeData
+        };
+    });