Im trying to make football player generator. Im using mongodb estimatedDocumentCount() to count amount of documents with certain data to increase ID of eash footballer by 1.

const footballersCounter = async () => {
    const counter = await dbo.collection('footballers').estimatedDocumentCount({});
    console.log(counter);
    return counter;
}

Since its async function i've to make fetching data async too:

const fetchFootballerBio = async (nameType) => {
    let output = [];

    switch (nameType) {
        case 'names':
            output = firstnames_m;
            break;
        case 'surnames':
            output = surnames;
            break;
        case 'footballerId':
            output = await (footballersCounter()   1);
            break;
    }
    return { data: output };
}

For names and surnames (it is json file with huge amount of names) I use randomising function:

function randomiser(warray) {
    var randomNumber = Math.floor(Math.random() * warray.length);
    return warray[randomNumber];
}

When function fetchFootballerBio is not async = names and surnames are working, but i footballerId gives [Promise pending]. When it is async i receive: TypeError: Cannot read properties of undefined (reading 'length')

Randomiser calls inside the function to generate the player:

function generateFootballer(teamName, nationality) {
    const firstNames = fetchFootballerBio('names');
    const lastNames = fetchFootballerBio('surnames');
    const footballerIds = fetchFootballerBio('footballerId');

    const firstName = randomiser(firstNames.data);
    const lastName = randomiser(lastNames.data);
    const footballerId = footballerIds.data;

    dbo.collection('footballers').insertOne({
        firstName: firstName,
        lastName: lastName,
        age: age,
        nation: nationalitySetup,
        footballerId: footballerId,
        position: position,
        teamName: teamNameSetup,
        skills: [{ speed: footballerSpeed }, { shooting: footballerShooting }, { control: footballerControl }, { passing: footballerPassing }, { defending: footballerDefending }, { handling: footballerHandling }]
    })

Any suggestions what can i do?

I've tried to run randomiser outside of switch, it worked perfectly for names and surnames.

CodePudding user response：

I can spot two things:

1. output = await (footballersCounter() 1); should be output = (await footballersCounter()) 1;, and
2. You need to make generateFootballer async and await the results. You are currently looking for a property named "data" on a Promise, which does not exist and so will supply undefined to randomiser (and this blows-up when you ask for the length property of undefined).

async function generateFootballer(teamName, nationality) {
    const firstNames = await fetchFootballerBio('names');
    const lastNames = await fetchFootballerBio('surnames');
    const footballerIds = await fetchFootballerBio('footballerId');

    const firstName = randomiser(firstNames.data);
    const lastName = randomiser(lastNames.data);
    const footballerId = footballerIds.data;

    dbo.collection('footballers').insertOne({
        firstName: firstName,
        lastName: lastName,
        age: age,
        nation: nationalitySetup,
        footballerId: footballerId,
        position: position,
        teamName: teamNameSetup,
        skills: [{ speed: footballerSpeed }, { shooting: footballerShooting }, { control: footballerControl }, { passing: footballerPassing }, { defending: footballerDefending }, { handling: footballerHandling }]
    })
}