Real-time push
CloudBase database supports listening for update events of data that matches the query criteria in collections.
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
- Web
// 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);
}
});
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.