I am currently working on creating a customized POST function for an express application in Node.js, inspired by Django's built-in REST methods. This function involves checking the mongo database for valid foreign keys and duplicates. The code snippet below demonstrates how the function makes initial calls to mongo to verify incoming foreign keys against the appropriate tables/collections.
However, I have encountered an issue with the response functionality within the native .map function causing an early return, while still executing the subsequent functions. Here is the problematic code:
const db = require(`../../models`)
const findInDB_by_id = async params => {
console.log(`querying db`)
const records = await Promise.all(Object.keys(params).map(function(table){
return db[table].find({
_id: {
$in: params[table]._ids
}
})
}))
console.log('done querying the db')
// process records further
return records
}
// execute findIndDB_by_id using await and perform other operations
// eventually return the response object
Below are the server logs:
querying db
POST <route> <status code> 49.810 ms - 9 // <- expected response
done querying the db
... other stuff
Modifying the map function to not return anything results in skipping the database query and delaying the express response object. By removing the 'return' command as shown below:
const records = await Promise.all(Object.keys(params).map(function(table){
db[table].find({ // removing the `return`
_id: {
$in: params[table]._ids
}
})
}))
The revised server logs indicate:
querying db
done querying the db
... other stuff
POST <route> <status code> 49.810 ms - 9 // <-expected response
This change, however, results in an empty query response since the modified function does not construct the query properly. I also noticed this behavior when trying arrow functions of the format .map(table => (...)).
If you have any insights, explanations, or suggestions regarding this behavior, please share them!