Import sql file in node.js and execute against PostgreSQL
Solution 1
I've written the following function which works for my case. It would have been much more simpler if it weren't for:
- Using
batch
to manage concurrency - Having the tricky PostgreSQL COPY case to consider
Code snippet:
function processSQLFile(fileName) {
// Extract SQL queries from files. Assumes no ';' in the fileNames
var queries = fs.readFileSync(fileName).toString()
.replace(/(\r\n|\n|\r)/gm," ") // remove newlines
.replace(/\s+/g, ' ') // excess white space
.split(";") // split into all statements
.map(Function.prototype.call, String.prototype.trim)
.filter(function(el) {return el.length != 0}); // remove any empty ones
// Execute each SQL query sequentially
queries.forEach(function(query) {
batch.push(function(done) {
if (query.indexOf("COPY") === 0) { // COPY - needs special treatment
var regexp = /COPY\ (.*)\ FROM\ (.*)\ DELIMITERS/gmi;
var matches = regexp.exec(query);
var table = matches[1];
var fileName = matches[2];
var copyString = "COPY " + table + " FROM STDIN DELIMITERS ',' CSV HEADER";
var stream = client.copyFrom(copyString);
stream.on('close', function () {
done();
});
var csvFile = __dirname + '/' + fileName;
var str = fs.readFileSync(csvFile);
stream.write(str);
stream.end();
} else { // Other queries don't need special treatment
client.query(query, function(result) {
done();
});
}
});
});
}
Beware that this would fail if you used semicolons anywhere except to terminate SQL statements.
Solution 2
You can just separate consequent queries with a semicolon when passed to client.query
That works:
var pg = require('pg');
pg.connect('postgres://test:test@localhost/test', function(err, client, done){
client.query('CREATE TABLE test (test VARCHAR(255)); INSERT INTO test VALUES(\'test\') ');
done();
});
And consequently, that works too:
var pg = require('pg');
var fs = require('fs');
var sql = fs.readFileSync('init_database.sql').toString();
pg.connect('postgres://test:test@localhost/test', function(err, client, done){
if(err){
console.log('error: ', err);
process.exit(1);
}
client.query(sql, function(err, result){
done();
if(err){
console.log('error: ', err);
process.exit(1);
}
process.exit(0);
});
});
Solution 3
The @databases/pg
client supports running SQL files out of the box:
const createPool = require('@databases/pg');
const {sql} = require('@databases/pg');
const db = createPool();
db.query(sql.file('my-file.sql')).catch(ex => {
console.error(ex);
process.exitCode = 1;
}).then(() => db.dispose());
It also supports having multiple statements in a single call to db.query
:
const createPool = require('@databases/pg');
const {sql} = require('@databases/pg');
const db = createPool();
db.query(sql`
INSERT INTO users (name) VALUES (${'Forbes'});
SELECT * FROM users;
`)).then(
results => console.log(results)
).catch(ex => {
console.error(ex);
process.exitCode = 1;
}).then(() => db.dispose());
In this example, each statement is run in sequence, and the result of the last statement is returned.
rgareth
Updated on July 30, 2022Comments
-
rgareth over 1 year
I'm looking for an efficient way to take a raw sql file and have it executed synchronously against a postgres database, akin to if you ran it through
psql
.I have an sql file which creates all databases, imports data, etc. I need to execute this using node.js but cannot find any module which does this automatically. For the node.js application itself, we use node-postgres ('pg'), knex.js and bookshelf.js. I assume though that pg is best for this.
One alternative I can think of is to read the full file, split it by semicolons, replace newlines with spaces, trim any duplicate space, then feed it into pg one by one in a manner that they're executed sequentially, not asynchronously. I'm a little surprised if this is truly the most efficient way and also if no libraries exist yet to solve this. I'm a little hesitant to jump into it seeing as SQL syntax can itself be a little challenging and I might accidentally mash it up.
Some clarifications in advance:
psql
cannot be used as it's not installed on the target machine- I've chosen to develop and source control sql statements in sql native form, because it's a lot easier for a DBA to use and manipulate it
-
rgareth about 10 yearsI tried this initially but found problems: * Newlines and tabs found traditionally in SQL files could not be stuffed into client.query, (resolvable with some extra steps) * Very difficult error handling per-query (which I have admittedly also left out of my example here)
-
OhJeez about 10 years@rgareth I had completely no problems with newlines and tabs in SQL files whatsoever. You can add some
\n
s (even\r\n
s) and\t
s to my example and it will still work. -
user2670818 over 8 yearsthat worked for me for ibm_db lib. I was facing the same problem also, but one question raised up to my mind. What about SQL Injection?
-
user7740901 almost 8 yearsCan you add details on what
batch
is? -
Alexander Pravdin over 4 yearsWhat about importing scripts with functions?
-
tukusejssirs over 3 yearswhile your answer helped me, you could mention that
@databases
packages are created by you. :smiley: … Also the docs (at your website) could be improve to contain more examples, e.g. I (as a Node JS newbie) had trouble to get where to put the connection options, because all your examples use a single string increateConnectionPool()
, however, I can put there an object with the supported connection options. Keep up the good work! -
ForbesLindesay about 3 yearsThanks for the feedback @tukusejssirs If you have suggestions for improvements to the docs, I'd love it if you could submit at PR. All the files you would need to edit are here: github.com/ForbesLindesay/atdatabases/tree/master/docs
-
Lee Goddard almost 2 yearsYou ought to edit your answer to mention you are the author of the packages you are recommending.