The issue lies in the nature of client.query being asynchronous, with results only accessible within the callback function.
One potential solution is utilizing async.js. For more insights, refer to this informative article.
As highlighted in the referenced article, you can iterate through a collection and execute code for each item. In your scenario, consider creating an array of indexes or using a foreach loop to generate an array of SQL query statements, subsequently executing operations for each query.
If 'queries' represents an array of query strings, then a possible implementation could look like:
async.forEach(queries, function(query, callback) {
client.query(query, function(err, row, fields){
array.push(row.rows[0]);
callback(); // indicating completion of this task to async
});
}, function(err) {
if (err) return next(err);
// all queries have been executed
});
It's worth noting that there are also forEachLimit method for parallel processing and forEachSeries for sequential execution.
UPDATE:
An improved approach involves leveraging async/await functionality, which is now accessible when using TypeScript compiled to ES6+ and working with node 4+ (which supports generators).
I delve into the specifics in my comprehensive repository on Node.js practices.
A snippet from the repo demonstrates awaiting an async call within a loop, ensuring asynchronous nature while pausing execution until completion. Additionally, it streamlines error handling through try/catch blocks.
// Leveraging await simplifies linear coding.
// Facilitates calling async functions within loops.
// Provides straightforward error management via try/catch.
var quotes: IQuote[];
var tries: number = 0;
while (true) {
try {
++tries;
// ASYNC/AWAIT
quotes = await this._store.find<IQuote>({});
break;
}
catch (err) {
if (tries == 3) { throw err; }
}
}
return quotes;