Performing multiple realtime database operations within firebase cloud function trigger

Question

I am attempting to generate an invitation code based on when a user adds data to the /households/{house_id} path using the onValueCreated() trigger provided by cloud functions.

exports.onCreateHousehold = onValueCreated("/households/{house_id}", (event) => {
        // We are not interested in adding a code if the household already exists
        if (event.data.child("code").val() != null) {
            return null;
        }

        // A 6 letter/number code translates to 2,176,782,336 possible combinations
        const codeLength = 6
        return generateCode(codeLength).then((code) => {
                log(`Household code generated: ${code}`);
                // With the code generated, save the code (this is the problem)
                addCode(event.params.house_id, event.data.child("owner").val(), code).then(() => {
                    log(`The code has been added :)`);
                })
            }
        )
    }
)

More specifically, I am generating a code:

/* House invitation code functions */

async function generateCode(codeLength) {
    var validCharacters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    var code = "";
    for (i = 0; i <= codeLength; i++) {
        code += validCharacters.charAt(parseInt(Math.random() * validCharacters.length));
    }
    // Check this code doesn't conflict with any existing household codes
    const codeMatch = await doesCodeMatch(code);
    if (codeMatch) {
        // Perform recursion until a unique code is found
        generateCode(codeLength);
    }
    return code;
}

Checking whether this code exists in any existing households:

async function doesCodeMatch(code) {
    const householdsRef = db.ref("households");
    // Wait until the database has been checked before returning the answer
    return await householdsRef
        .equalTo(code)
        .once("value", (data) => {
            return data.exists()
        });
}

Then writing the invitation code to the household:

async function addCode(houseID, userID, code) {
    const householdData = {
        code: code
    };
    const updates = {};
    updates[`/households/${houseID}`] = householdData;
    updates[`/users/${userID}/households/${houseID}`] = householdData;
    return await update(ref(db), updates);
}

However every time this function runs I get the error RangeError: Maximum call stack size exceeded.

I have attempted to run addCode() on its own in the onValueCreated() function just to see if updating the /households/{house_id} was causing some loop where onValueCreated() would be retriggered continuously but this wasn't a problem and the code was added to the path:

exports.onCreateHousehold = onValueCreated("/households/{house_id}", (event) => {
        if (event.data.child("code").val() != null) {
            return null;
        }

        // This works fine and F45FD3 gets added
        addCode(event.params.house_id, event.data.child("owner").val(), "F45FD3").then(() => {
            log(`The code has been added :)`);
        })
    }
)

This led me to believe then it is something to do with multiple operations being made to the realtime database. Is it possible to make multiple read/writes/updates etc. to the realtime database within a single cloud function trigger, and if so, how could this be done?

Answer 1

@Doug Stevenson led me onto the right idea and this was indeed a promise issue. doesCodeMatch() was passing back a promise that I incorrectly assumed was of a boolean type but it was actually a data snapshot. Therefore if (codeMatch) {} was always returning true and generateCode(codeLength) was being called on indefinitely causing a stack overflow! The code was changed to as follows and both generateCode() and addCode now executes:

if (codeMatch.exists()) {
    // Perform recursion until a unique code is found
    code = generateCode(codeLength);
}