.toArray() in Javascript returns undefined even with .then()

Question

I am using mongo to search for all entries with a value that is like whatever is passed into the searchForAsset method. When I use the .toArray method and I console.log(result) the array of files is printed in array format. However when I return that exact same variable below the console.log and I console.log it in the .then() below, it comes back as "result: undefined". Why doesn't the .then() wait for the result to be returned correctly?

async function searchForAsset(nameToQuery){
    const client = await mongoConnect()
    client.db(process.env.DATABASE_NAME).collection(process.env.ASSET_COLLECTION).find({asset_name: RegExp(nameToQuery)}).toArray(function(err, result) {
        if (err) throw err
        console.log(result)
        client.close()
        return result
    })
}

searchForAsset("Solution").then(result => {
    console.log("result: "+result)
})

Edit: I changed the code to this and it still returns undefined:

async function searchForAsset(nameToQuery){
    const client = await mongoConnect()
    const result = await client.db(process.env.DATABASE_NAME).collection(process.env.ASSET_COLLECTION).find({asset_name: RegExp(nameToQuery)}).toArray(function(err, result) {
        if (err) throw err
        console.log(result)
        client.close()
    })
    return result
}

searchForAsset("Solution").then(result => {
    console.log("result: "+result)
})

Why aren't you using await in an async function? const result = await client.db(process.env.DATABASE_NAME).collection(process.env.ASSET_COLLECTION).find({asset_name: RegExp(nameToQuery)}).toArray() or you need to add return before client.db(...) — Dharmaraj
– Dharmaraj, Commented Jul 22, 2021 at 15:54
searchForAsset is not returning anything. If there's no return statement in a function, you will get undefined — Evert
– Evert, Commented Jul 22, 2021 at 15:57
@Dharmaraj @Evert if I change the method to const result = await client.db(process.env.DATABASE_NAME).collection(process.env.ASSET_COLLECTION).find({asset_name: RegExp(nameToQuery)}).toArray(function(err, result) {}) and then after that do return result it still results in an undefined console.log() in the .then() — Riley Eaton
– Riley Eaton, Commented Jul 22, 2021 at 16:28
You don't use call back with await generally. Try copying code from this gist — Dharmaraj
– Dharmaraj, Commented Jul 22, 2021 at 16:30
@Dharmaraj then the return looks like this: result: [object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]... and so on — Riley Eaton
– Riley Eaton, Commented Jul 22, 2021 at 16:33

Dharmaraj · Accepted Answer · 2021-07-22 16:35:18Z

1

Try using await as the function is async like this:

async function searchForAsset(nameToQuery){
    const client = await mongoConnect()
    const result = await client.db(process.env.DATABASE_NAME).collection(process.env.ASSET_COLLECTION).find({asset_name: RegExp(nameToQuery)}).toArray()
    return result 
}

searchForAsset("Solution").then(result => {
    console.log("result: "+result)
})

About that [object Object] being logged. Try stringifying that:

console.log(JSON.stringify(result))

Then to view it in a prettier way, copy the log output and paste it in https://jsonformatter.org/

answered Jul 22, 2021 at 16:35

Dharmaraj

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2 Comments

Riley Eaton Over a year ago

yes the console.log(JSON.stringify(result)) works but for large outputs its just a wall of text, how can I turn this back into a json that looks nice

Dharmaraj Over a year ago

@RileyEaton like view it yourself or in your app? Try using the JSON Formatter

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