How to run function once in a mongodb result array?

Hello, I think I not fully understand how to works with the data.

After a mongo find request I got this kind of result :

[
    {
        "_id": "601151e7962b1d29063781f9",
        "email": "[email protected]"
    },
    {
        "_id": "60115244962b1d29063781fb",
        "email": "[email protected]"
    }
]

I’m trying to write a boolean function to know if the db return exactly 0 element.

I would like to wrote a function resultAreEmpty which shloud return a boolean.

if(item.length == 0){
    return true;
} else {
    return false;
}

If I use a function item the result is [false, false] and I only want it to return false in this case.
If i use a function it asks me too return an object with a json property.

What is the best way to consider the result send by mongogb get as one object only ?

Welcome to the community. @mairkur

[
    {
        "_id": "601151e7962b1d29063781f9",
        "email": "[email protected]"
    },
    {
        "_id": "60115244962b1d29063781fb",
        "email": "[email protected]"
    }
]

Just to be sure, is the output of the Mongo DB node?

I’m trying to write a boolean function to simply return if the db return 0 or more elements.

Then it will always return? as you will always have 0 or more elements. Not sure if I understand this.

If I use a function item the result is [false, false] and I only want it to return false in this case.
If i use a function it asks me too return an object with a json property.

What is the best way to consider the result send by mongogb get as one object only ?

By default, if the MongoDB node does not return values the next node will not be executed. You have to go to setting -> Always Output Data and set it to true.

After that, you might want to change the function item node to a function node add the following

const results = []

if(items.length === 0){
    results.push({ json: { result: true } });
} else {
    results.push({ json: { result: false }});
}

return results

Hope that helps.

Thanks for your answer !

Yes that’s it :slight_smile:

My sentence is bad sorry, I juste want to know if the mongodb return a result or not.
(example : If the db return 0 elements, the user email is not found then I can create the account.)

Well because when no result are found the mongo node return

[{}]

items.length will be equal to 1 when there is 0 or 1 result found.

How to test the result is something else than [{}] ?

Change it to:

const results = []

if(Object.keys(items[0].json).length === 0){
    results.push({ json: { returnedResults: false } });
} else {
    results.push({ json: { returnedResults: true }});
}

return results

Thanks a lot !