[js][android] Support multiple listeners on a single ref

lib/modules/database/query.js

@@ -9,47 +9,41 @@ import Reference from './reference.js';
  * @class Query
  */
 export default class Query extends ReferenceBase {
-  static ref: Reference;
+  modifiers: Array<DatabaseModifier>;
 
-  static modifiers: Array<string>;
-
-  ref: Reference;
-
-  constructor(ref: Reference, path: string, existingModifiers?: Array<string>) {
+  constructor(ref: Reference, path: string, existingModifiers?: Array<DatabaseModifier>) {
     super(ref.database, path);
     this.log.debug('creating Query ', path, existingModifiers);
-    this.ref = ref;
     this.modifiers = existingModifiers ? [...existingModifiers] : [];
   }
 
-  setOrderBy(name: string, key?: string) {
-    if (key) {
-      this.modifiers.push(`${name}:${key}`);
-    } else {
-      this.modifiers.push(name);
-    }
+  orderBy(name: string, key?: string) {
+    this.modifiers.push({
+      type: 'orderBy',
+      name,
+      key,
+    });
   }
 
-  setLimit(name: string, limit: number) {
-    this.modifiers.push(`${name}:${limit}`);
+  limit(name: string, limit: number) {
+    this.modifiers.push({
+      type: 'limit',
+      name,
+      limit,
+    });
   }
 
-  setFilter(name: string, value: any, key?:string) {
-    if (key) {
-      this.modifiers.push(`${name}:${value}:${typeof value}:${key}`);
-    } else {
-      this.modifiers.push(`${name}:${value}:${typeof value}`);
-    }
+  filter(name: string, value: any, key?:string) {
+    this.modifiers.push({
+      type: 'filter',
+      name,
+      value,
+      valueType: typeof value,
+      key,
+    });
   }
 
-  getModifiers(): Array<string> {
+  getModifiers(): Array<DatabaseModifier> {
     return [...this.modifiers];
   }
-
-  getModifiersString(): string {
-    if (!this.modifiers || !Array.isArray(this.modifiers)) {
-      return '';
-    }
-    return this.modifiers.join('|');
-  }
 }