Firestore docs give details of how to manually calculate the stored size of a document, but there does not seem to be a function provided for this on any of document reference, snapshot, or metadata.
Before I attempt to use my own calculation, does anyone know of an official or unofficial function for this?
Here is my (completely untested) first cut for such a function from my interpretation of the docs at https://firebase.google.com/docs/firestore/storage-size
function calcFirestoreDocSize(collectionName, docId, docObject) {
let docNameSize = encodedLength(collectionName) + 1 + 16
let docIdType = typeof(docId)
if(docIdType === 'string') {
docNameSize += encodedLength(docId) + 1
} else {
docNameSize += 8
}
let docSize = docNameSize + calcObjSize(docObject)
return docSize
}
function encodedLength(str) {
var len = str.length;
for (let i = str.length - 1; i >= 0; i--) {
var code = str.charCodeAt(i);
if (code > 0x7f && code <= 0x7ff) {
len++;
} else if (code > 0x7ff && code <= 0xffff) {
len += 2;
} if (code >= 0xDC00 && code <= 0xDFFF) {
i--;
}
}
return len;
}
function calcObjSize(obj) {
let key;
let size = 0;
let type = typeof obj;
if(!obj) {
return 1
} else if(type === 'number') {
return 8
} else if(type === 'string') {
return encodedLength(obj) + 1
} else if(type === 'boolean') {
return 1
} else if (obj instanceof Date) {
return 8
} else if(obj instanceof Array) {
for(let i = 0; i < obj.length; i++) {
size += calcObjSize(obj[i])
}
return size
} else if(type === 'object') {
for(key of Object.keys(obj)) {
size += encodedLength(key) + 1
size += calcObjSize(obj[key])
}
return size += 32
}
}