I have a sqlite3 database request in my main.js, that is triggered by button click in renderer.js.
The request reaches my main.js. However, I cannot manage to await the results from the database. The issue occurs already in main.js, so I'm stuck even before anything is passed back to the renderer.js.
I hope someone can tell me what I am missing.
Here is my code:
renderer.js
$(document).on('click','#mybtn',function(e){
let query = "SELECT id, name FROM table1"
// send (here is the issue)
window.api.send("db-query", query)
// (next step: receive, might be wrong but not yet my problem)
window.api.receive(channel="receive-db-data", (data) => {
console.log(data);
});
});
main.js
ipcMain.on(channel='db-query', async (e, query) => {
console.log('query received: ' + query);
let data = await db_request(query).then(
function(value) {
console.log('value: ' + value);
return value;
},
function(error) {
console.log('error fetching data from db on query:' + query);
}
)
console.log("response ready: " + data); //returns undefined if 'return value' is used (otherwise nothing)
// to send back to renderer.js later
e.sender.send("db-data", data)
})
let db_request = async (query) => {
let data = []
var sqlite3 = require('sqlite3').verbose();
var dbPath = require('path').resolve(__dirname, '../../Fin.db')
var db = new sqlite3.Database(dbPath)
db.serialize(function(){
db.each(query, function(err, row) {
console.log(row)
data.push({"id": row.id, "name": row.name})
});
});
db.close();
console.log('db_request:' + data)
return data
}
And this is how my terminal looks like:
query received: SELECT id, type, name FROM table1
db_request:
value:
response ready: undefined
{ id: 1, name: 'a' }
{ id: 2, name: 'b' }
{ id: 3, name: 'c' }
You have to convert db_request result to a Promise, and the promise will be resolved when all rows are pushed to the data. When you use the await keyword, there is no need to handle a promise with .then chain.
main.js will look like this:
const sqlite3 = require('sqlite3').verbose();
const dbPath = require('path').resolve(__dirname, '../../Fin.db')
ipcMain.on(channel='db-query', async (e, query) => {
console.log('query received: ' + query)
try {
const data = await db_request(query); // remove .then
console.log('value: ' + data)
// to send back to renderer.js later
e.sender.send("db-data", data)
} catch (error) {
console.log('error fetching data from db on query:' + query);
e.sender.send("db-data", []) // send empty data or error ???
}
})
let db_request = (query) => {
const db = new sqlite3.Database(dbPath)
return new Promise((resolve, reject) => { // return a promise
// I think you dont need serialize for this case
const data = []
db.each(query, (err, row) => {
console.log(err, row)
if (!err) {
data.push({"id": row.id, "name": row.name})
}
}, (error) => {
if (error) {
reject(error)
} else {
resolve(data)
}
});
})
}