query ranges lib and tests

client/lib/databasable.js

@@ -0,0 +1,43 @@
+const DEFAULTS = {
+  adapter: ''
+};
+
+var databasable = {
+
+  accessDb: function(db_name, opts){
+    var databasable = this;
+    opts = Object.assign(Object.assign({}, DEFAULTS), opts || {});
+    return new Promise((fnResolve, fnReject){
+      if (!databasable.db) {
+        databasable.db = new Loki(db_name, opts);
+        databasable.db.loadDatabase({}, ()=>{
+          fnResolve(databasable.db);
+        });
+      } else { fnResolve(databasable.db); }
+    });
+  },
+
+  closeDb: function(){
+    var databasable = this;
+    if (databasable.db){
+      databasable.db.save();
+      databasable.db.close();
+      databasable.db = undefined;
+    }
+  },
+
+  collection(collection_name, options){
+    var databasable = this;
+    databasable.accessDb()
+      .then((db)=>{
+        var collection = db.getCollection(collection_name)
+        if (!collection){
+          collection = db.addCollection(collection_name, options);
+        }
+        return collection;
+      });
+  }
+
+};
+
+export default databaseable;