basic entity support with lazy loaded relations

src/services/sql.js

@@ -7,6 +7,9 @@ const sqlite = require('sqlite');
 const app_info = require('./app_info');
 const resource_dir = require('./resource_dir');
 const Note = require('../entities/note');
+const NoteRevision = require('../entities/note_revision');
+const NoteTree = require('../entities/note_tree');
+const Attribute = require('../entities/attribute');
 
 async function createConnection() {
     return await sqlite.open(dataDir.DOCUMENT_PATH, {Promise});
@@ -137,13 +140,40 @@ async function getRows(query, params = []) {
 async function getEntities(query, params = []) {
     const rows = await getRows(query, params);
 
-    return rows.map(row => new Note(module.exports, row));
+    return rows.map(createEntityFromRow);
 }
 
 async function getEntity(query, params = []) {
-    const rows = await getRows(query, params);
+    const row = await getRowOrNull(query, params);
 
-    return rows.map(row => new Note(module.exports, row));
+    if (!row) {
+        return null;
+    }
+
+    return createEntityFromRow(row);
+}
+
+function createEntityFromRow(row) {
+    let entity;
+    let sql = module.exports;
+
+    if (row.attributeId) {
+        entity = new Attribute(sql, row);
+    }
+    else if (row.noteRevisionId) {
+        entity = new NoteRevision(sql, row);
+    }
+    else if (row.noteTreeId) {
+        entity = new NoteTree(sql, row);
+    }
+    else if (row.noteId) {
+        entity = new Note(sql, row);
+    }
+    else {
+        throw new Error('Unknown entity type for row: ' + JSON.stringify(row));
+    }
+
+    return entity;
 }
 
 async function getMap(query, params = []) {