Currently, I have some code that query from Neo4j database then write to a CSV file on server:
const session = driver.session();
const query = '<my query>';
var file = fs.createWriteStream('export.csv');
file.write('<some CSV header here');
await new Promise((resolve, reject) => {
session.run(query).subscribe({
onNext: i => {
file.write('<data of record i>');
},
onCompleted: () => {
session.close()
file.end()
resolve()
},
onError: error => {
console.log(error)
reject()
}
})
})
return response.download('export.csv');
Everything is fine until now I have more data in the database so the process to write a CSV file takes a long time, then the client receives a timeout error.
I have found a couple of solutions that use pipe() to send stream directly to the client but I tried it and failed because the result of session.run() is an observable not stream. Is there any other way?
Note: I'm using AdonisJs for backend
You can write data directly into the response like this:
const session = driver.session();
const query = '<my query>';
response.response.writeHead(200, {
'Content-Type': 'application/csv',
'Content-Disposition': 'attachment; filename="export.csv"'
});
response.response.write('<some CSV header here');
await new Promise((resolve, reject) => {
const results = session.run(query).subscribe({
onNext: i => {
response.response.write('<data of record i>');
},
onCompleted: () => {
session.close()
response.response.end()
resolve()
},
onError: error => {
console.log(error)
reject()
}
})
})