如何使用 firestore 检查 id 是否已存在于 React 中？

Question

This is the code where I add data to firestore. How can I check if idEveniment field already exist in collection? And if exist I dont want to add the new collection. Maybe return an error?

import { firestore } from 'firebase';

// Add Eveniment
export const addEveniment = data => async(dispatch, getState, {getFirestore}) => {
    
    const firestore = getFirestore();
    const userId = getState().firebase.auth.uid;
    dispatch({type: actions.ADD_EVENIMENT_START});
    try {
        const res = await firestore.collection('evenimente').doc(userId).get();
        
        const newEveniment = {
            idEveniment: data.idEveniment, 
            eveniment: data.eveniment,
        }
        if(!res.data()) {
            firestore.collection('evenimente').doc(userId).set({
                evenimente: [newEveniment],
            });
        } else {
            firestore.collection('evenimente').doc(userId).update({
                evenimente: [...res.data().evenimente, newEveniment],
            });
        }
        

        dispatch({type: actions.ADD_EVENIMENT_SUCCESS});
        return true;
    } catch(err) {
        dispatch({type: actions.ADD_EVENIMENT_FAIL, payload: err.message})
    }
        
}

Answer 1

In your current data structure you can't check for documents with a specific value of idEveniment . You can use array-contains to check array membership but only if you specify the combinarion of idEveniment and eveniment .

If you want to be able to check just on the value of idEveniment , consider adding a field idEveniments to each document with just that value. Then you can use array-contains for the existing of a specific idEveniment value in the idEveniments array:

const evenimentesRef = firebase.firestore().collection("evenimente");
const query = evenimentesRef.where("idEveniments", "array-contains", "376342").limit(1);
query.get().then((snapshot) => {
  if (!snapshot.empty()) {
    ... a document with the value already exists
  }
});