How do you read data from firestore?

Question

I'm trying to learn how to use firestore.

The google documentation says to try this format:

db.collection("users").get().then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
        console.log(`${doc.id} => ${doc.data()}`);
    });
});

So, I used that to do this (changing the db to fsDB and "users" to "newsletters"

fsDB.collection("newsletters").get().then((querySnapshot) => {
    querySnapshot.forEach((doc) => {
        console.log(`${doc.id} => ${doc.data()}`);
    });
});

When I try this, I get an error that says querySnapshot is not defined. Screen shot of error message is attached.

I've seen this post and tried its suggestion as follows:

fsDB.collection("newsletters").query.get().then(function(querySnapshot) { 

                            if (querySnapshot.empty) { 
                                console.log('no documents found');
                            } else {
                                    querySnapshot.docs.map(function (documentSnapshot) {
                                        console.log(documentSnapshot.data().name); 
                                    });
                            }

                        });

This attempt generates a parsing error with the if statement, but I can't find a way to solve that either.

This must have a simple solution, but I can't figure out how to get a record from the database.

NEXT ATTEMPT

I tried moving the code above the return statement and putting in inside a variable as follows shown in the attached screen shot, but it still produces errors as shown. These errors are the same regardless of whether i keep or lose the brackets around querySnapshot.

ADD STATE

class Fndate extends React.Component {
    state = {
        options: [],
        anzic: [],
        country: [],
        region: [],

    }

    selectCountry (val) {
        this.setState({ country: val });
      }

      selectRegion (val) {
        this.setState({ region: val });
      }

    async componentDidMount() {
        // const fsDB = firebase.firestore(); // Don't worry about this line if it comes from your config.
        let options = [];
        await fsDB.collection("abs_for_codes").get().then(function (querySnapshot) {
        querySnapshot.forEach(function(doc) {
            console.log(doc.id, ' => ', doc.data());
            options.push({
                value: doc.data().title.replace(/( )/g, ''),
                label: doc.data().title + ' - ABS ' + doc.id
            });
            });
        });


        let anzic = [];
        await fsDB.collection("anzic_codes").get().then(function (querySnapshot) {
        querySnapshot.forEach(function(doc) {
            console.log(doc.id, ' => ', doc.data());
            anzic.push({
                value: doc.data().Title.replace(/( )/g, ''),
                label: doc.data().Title + ' - ANZIC ' + doc.id
            });
            });
        });


            await fsDB
            .collection("newsletter")
            .get().then((querySnapshot) => {
                querySnapshot.forEach((doc) => {
                console.log(`${doc.id} => ${doc.data().email}`);
                }
            );
            });

        this.setState({
            options,
            anzic
        });
    }

5]5

Answer 1

You can use an automated script for this. All you need is python and firebase_admin.

1. pip install firebase_admin
2. download https://github.com/harshit0209/firestore_backup
3. now run getData.py script.
4. give it the path of your firebase project private key.
5. now give the document name.

Answer 2

I believe you're using React, and I just realized that you're calling the method in question in the render method.

try doing it in componentDidMount. A reference can be found here

so your code would be like this:

class YourClass extends React.Component {
   componentDidMount(){
      fsDB.collection("newsletters").get().then((querySnapshot) => {
         querySnapshot.forEach((doc) => {
            console.log(`${doc.id} => ${doc.data()}`);
         });
      });
   }
   render(){
      return (....your existing jsx....)
   }
}

Note that I don't know your class name or how you define your component. But I'm just saying that you need to move your code in the componentDidMount.

We couldn't see your entire file. But I'm sure that it's a syntax error (especially with JSX)

Answer 3

I think you should get rid of ‘.query’. and the .empty returns false if you have data in the collection. but i wonder, why is querySnapshot undefined in your case.

db.collection("lessons").get()
  .then(function(querySnapshot) { 
    if (!querySnapshot.empty) {
        querySnapshot.docs.map(function(documentSnapshot) {
        console.log(documentSnapshot.data().name); 
     })
    } else {
    console.log('no documents found');
    }   
});

console