Real-time push

CloudBase database supports listening for update events of data that matches the query criteria in collections.

Classic mode only

The realtime database is a classic-mode capability; PG-mode environments have no watch(). To listen to table changes in PG mode, use app.realtime().

PostgreSQL table changes, Broadcast, and Presence

Keep using watch() on this page for document-database collections. For Broadcast / Presence / PostgreSQL CDC, use JS SDK app.realtime().

Setting Up a Listener

Use the watch() method to set up a listener, which returns a watcher object for closing the listener.

Any change in the documents that meet the conditions will trigger the onChange callback.

Mini Program

// 1. Get the database reference
const db = wx.cloud.database();

const watcher = db
    .collection("todos")
    .where({
        // query...
    })
    .watch({
        onChange: function(snapshot) {
            console.log("snapshot", snapshot);
        },
        onError: function(err) {
            console.error("the watch closed because of error", err);
        }
    });

Web

const cloudbase = require("@cloudbase/js-sdk");

const app = cloudbase.init({
    env: "xxxx"
});
// 1. Get the database reference
var db = app.database();

const watcher = db
    .collection("todos")
    .where({
        // query...
    })
    .watch({
        onChange: function(snapshot) {
            console.log("snapshot", snapshot);
        },
        onError: function(err) {
            console.error("the watch closed because of error", err);
        }
    });

Closing the Listener

Call watcher.close() to close the listener.