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samthecodingman/firestoreTransforms.js

Created January 1, 2020 04:48
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  1. samthecodingman created this gist Jan 1, 2020.
    66 changes: 66 additions & 0 deletions firestoreTransforms.js
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    /*! firestoreTransforms.js | Samuel Jones 2019 | MIT License | gist.github.com/samthecodingman */

    /**
    * @file A file containing common firestore idioms used with queries
    * @author Samuel Jones 2017 (github.com/samthecodingman)
    * @license MIT
    * @module firestore-transforms
    */

    /**
    * Cloud Firestore QuerySnapshot
    * @external "firebase.firestore.QuerySnapshot"
    * @see {@link https://firebase.google.com/docs/reference/js/firebase.firestore.QuerySnapshot|firebase.firestore.QuerySnapshot}
    */

    /**
    * Transforms the children of a given query snapshot to an array of objects
    * @param {!external:firebase.firestore.QuerySnapshot} querySnapshot - The snapshot containing data to transform.
    * @param {?string="id"} idFieldName - The name of the property to be set to the child's document ID. If null, the document ID is not merged into each object.
    * @return {!Object[]} - The array of children of the given query snapshot.
    * @public
    */
    function childrenAsArrayOfObjects(querySnapshot, idFieldName) {
    let children = [];
    if (idFieldName === null) {
    querySnapshot.forEach(childDoc => children.push(childDoc.data()))
    } else {
    let idFieldName = (idFieldName && idFieldName + "") || "id";
    querySnapshot.forEach(childDoc => {
    children.push({...childDoc.data(), [idFieldName]: childDoc.id})
    })
    }
    return children;
    }

    /**
    * Transforms the children of a given query snapshot to an array of document IDs
    * @param {!external:firebase.firestore.QuerySnapshot} querySnapshot - The snapshot containing data to transform.
    * @return {!string[]} - The array of document IDs that are children of the given query snapshot.
    * @public
    */
    function childrenAsArrayOfIDs(querySnapshot) {
    let ids = [];
    querySnapshot.forEach(childDoc => ids.push(childDoc.id));
    return ids;
    }

    /**
    * Transforms the children of a given query snapshot to a object with each child as a mapped property.
    * @param {!external:firebase.firestore.QuerySnapshot} querySnapshot - The snapshot containing data to transform.
    * @return {!Object} - The object that contains the children of the given query snapshot.
    * @public
    */
    function childrenAsMappedObject(querySnapshot) {
    let mapObj = [];
    querySnapshot.forEach(childDoc => {
    mapObj[childDoc.id] = childDoc.data();
    })
    return mapObj;
    }

    module.exports = {
    childrenAsArrayOfObjects,
    childrenAsArrayOfIDs,
    childrenAsMappedObject
    }