126 lines
4.1 KiB
JavaScript
126 lines
4.1 KiB
JavaScript
/* This example is to show the preferred way to use the td-connector */
|
|
/* To run, enter node path/to/node-example.js */
|
|
// Get the td-connector package
|
|
const taos = require('td2.0-connector');
|
|
|
|
/* We will connect to TDengine by passing an object comprised of connection options to taos.connect and store the
|
|
* connection to the variable conn
|
|
*/
|
|
/*
|
|
* Connection Options
|
|
* host: the host to connect to
|
|
* user: the use to login as
|
|
* password: the password for the above user to login
|
|
* config: the location of the taos.cfg file, by default it is in /etc/taos
|
|
* port: the port we connect through
|
|
*/
|
|
var conn = taos.connect({host:"127.0.0.1", user:"root", password:"taosdata", config:"/etc/taos",port:0});
|
|
|
|
// Initialize our TDengineCursor, which we use to interact with TDengine
|
|
var c1 = conn.cursor();
|
|
|
|
// c1.query(query) will return a TaosQuery object, of which then we can execute. The execute function then returns a promise
|
|
// Let's create a database named db
|
|
try {
|
|
var query = c1.query('create database db;');
|
|
query.execute();
|
|
}
|
|
catch(err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Now we will use database db. As this query won't return any results,
|
|
// we can simplify the code and directly use the c1.execute() function. No need for a TaosQuery object to wrap around the query
|
|
try {
|
|
c1.execute('use db;');
|
|
}
|
|
catch (err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Let's create a table called weather
|
|
// which stores some weather data like humidity, AQI (air quality index), temperature, and some notes as text
|
|
// We can also immedietely execute a TaosQuery object by passing true as the secodn argument
|
|
// This will then return a promise that we can then attach a callback function to
|
|
try {
|
|
var promise = c1.query('create table if not exists weather (ts timestamp, humidity smallint, aqi int, temperature float, notes binary(30));', true);
|
|
promise.then(function(){
|
|
console.log("Table created!");
|
|
}).catch(function() {
|
|
console.log("Table couldn't be created.")
|
|
});
|
|
}
|
|
catch (err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Let's get the description of the table weather
|
|
// When using a TaosQuery object and then executing it, upon success it returns a TaosResult object, which is a wrapper around the
|
|
// retrieved data and allows us to easily access data and manipulate or display it.
|
|
try {
|
|
c1.query('describe db.weather;').execute().then(function(result){
|
|
// Result is an instance of TaosResult and has the function pretty() which instantly logs a prettified version to the console
|
|
result.pretty();
|
|
});
|
|
}
|
|
catch (err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Let's try to insert some random generated data to test with
|
|
// We will use the bind function of the TaosQuery object to easily bind values to question marks in the query
|
|
// For Timestamps, a normal Datetime object or TaosTimestamp or milliseconds can be passed in through the bind function
|
|
let stime = new Date();
|
|
let interval = 1000;
|
|
try {
|
|
for (let i = 0; i < 1000; i++) {
|
|
stime.setMilliseconds(stime.getMilliseconds() + interval);
|
|
let insertData = [stime,
|
|
parseInt(Math.random()*100),
|
|
parseInt(Math.random()*300),
|
|
parseFloat(Math.random()*10 + 30),
|
|
"\"random note!\""];
|
|
//c1.execute('insert into db.weather values(' + insertData.join(',') + ' );');
|
|
var query = c1.query('insert into db.weather values(?, ?, ?, ?, ?);').bind(insertData);
|
|
query.execute();
|
|
}
|
|
}
|
|
catch (err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Now let's look at our newly inserted data
|
|
var retrievedData;
|
|
try {
|
|
c1.query('select * from db.weather limit 5 offset 100;', true).then(function(result){
|
|
result.pretty();
|
|
// Neat!
|
|
});
|
|
|
|
}
|
|
catch (err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
// Let's try running some basic functions
|
|
try {
|
|
c1.query('select count(*), avg(temperature), max(temperature), min(temperature), stddev(temperature) from db.weather;', true)
|
|
.then(function(result) {
|
|
result.pretty();
|
|
})
|
|
}
|
|
catch(err) {
|
|
conn.close();
|
|
throw err;
|
|
}
|
|
|
|
conn.close();
|
|
|
|
// Feel free to fork this repository or copy this code and start developing your own apps and backends with NodeJS and TDengine!
|