How do I get Map object from firebase in typescript

Question

I am writing cloud function in TypeScript, and trying to get Map object - AKA (nested objects, called maps) from firebase so I would be able to iterate through it.

This is the structure in my Firebase:

And I am trying to get the data like:

const tokenSettingsRef = db.collection('tokenSettings').doc('spread')
transaction.get(tokenSettingsRef).then((tokenSettingsDocSnapshot) => {


                            const tokenData = tokenSettingsDocSnapshot.data()
                            if (typeof tokenData !== 'undefined') {
                                console.log("tokennne3: " + tokenData.tokens[0])
                                console.log("tokennne4: " + tokenData)
                                console.log("tokennne5: " + tokenData.tokens)
                                console.log("tokennne1: " + tokenData.tokens.length())
                                console.log("tokennne2: " + tokenData.tokens.keys())
                                const variations = new Map(Object.entries(tokenData.tokens));
                                console.log("tokennne5: " + variations.keys)
                                console.log("tokennne6: " + variations.values)

None of the above doesn't give me Map so I could use it... Or log it out. I am getting data but all I can see is smtg like [object Object]

What am I missing here, I didn't have any issues with getting arrays or plain objects...

Renaud Tarnec · Accepted Answer · 2021-10-18 04:08:05Z

5

Based on the code in your question, I make the assumption that you read your data within a transaction.

The following should work:

var tokenSettingsRef = db.collection('tokenSettings').doc('spread');

db.runTransaction(transaction => {
    return transaction.get(tokenSettingsRef).then(tokenSettingsDocSnapshot => {

        if (!tokenSettingsDocSnapshot.exists) {
            throw "Document does not exist!";
        }

        var tokensMap = tokenSettingsDocSnapshot.data().tokens;
        //Let's print all the keys and values of the tokens map
        Object.keys(tokens).forEach(e =>
          console.log(`key=${e}  value=${tokens[e]}`)
        );
        //...... Continue the transaction
    });
}).then(function() {
    //....
})
.catch(error => {
    console.log('Transaction failed: ', error);
});

If you want to "get Map<number, number> object out of it", as asked in your comment below, you could do as follows:

var tokensMap = tokenSettingsDocSnapshot.data().tokens;

  const transformedTokensMap = new Map<number, number>();
  Object.keys(tokensMap).forEach(e => {
      transformedTokensMap.set(Number(e), tokensMap[e]);
});

edited Oct 18, 2021 at 4:08

answered Nov 6, 2019 at 20:31

Renaud Tarnec

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5 Comments

5er Over a year ago

this works, thanks. How do I get Map object out of it, please?

Renaud Tarnec Over a year ago

Have a look at the specific section of the doc "Passing information out of transactions": firebase.google.com/docs/firestore/manage-data/…

5er Over a year ago

I don't want to pass it outside of the transaction I want to use values inside the map for generating documents. I have a function that accepts Map<number, number> and I want to pass tokensMap to that function as a Map<number, number>.

5er Over a year ago

do you have any advice on how to do that? Get Map<number, number> object out of it? Thanks

5er Over a year ago

I did it this way, but I was hoping there is an easier way to do it... Thank you very very much...

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