So, a little background about what I'm trying to create. I am trying to build a voting app, where a MongoDb database stores the options and the counters for each of those options to check how many times people have voted for each option. The data structure I have implemented looks like below.
_id:"57dfecfa3832360f46e183c2"
options:"iea, aoegboae, aoeugoa, ougr, gege"
options_counter:Object
0:0
1:0
2:0
3:0
4:0
__proto__:Object
title:"hr"
Each of those numbers [0,1,2,3,4] represents an option and the number after the colon represents the counter for each. My function to update the required counter is shown below
var fieldToIncrement = db.collection('polls').options_counter.field;
db.collection('polls').findOneAndUpdate(
{_id: user_id},
{$inc: {fieldToIncrement: 1}},
{upsert:false},
{returnNewDocument: true}
).toArray(function(err, doc){
if(err){
throw new Error(err);
}if(doc){
console.log(doc);
//callback(null, doc);
}
});
However, using the fieldToIncrement variable returns an error saying that cannot find property field of undefined. The variable field contains the number specifying the specific key of the options_counter object that needs to be incremented by 1. I have embedded the options_counter within the original document. My question is how do I set up the syntax so that MongoDb can find the specific key value pair within the options_counter object to update, and increment that counter by 1?
It looks like "options_counter" is a embedded document, for this you var fieldToIncrement has to be something like options_count.0.
I can't see this in your question.
please share your code where you define fieldToIncrement, is now seems undefined as also stated in the error you mentioned: "However, using the fieldToIncrement variable returns an error saying that cannot find property field of undefined."
Related
So I'm working on a personal project to learn react-native and Firestore.
I have a DB like this:
And I want my code to add a new battery in the array batteries.
The elements in the array are just a map{string, string}
The problem is that when I update the array with a new brand that's work but if I want to update it with the same brand again have,
so having by the end
batteries[0]: {'brand': 'cestmoi'}
batteries[1]: {'brand': 'cestmoi'}
The DB doesn't update, doesn't have any error or so.
I don't understand why and I followed their tutorial. Here is my code:
async function addData(collection, doc, value) {
console.log(`Add data ${value.brand}`)
try {
const result = await firestore()
.collection(collection)
.doc(doc)
.set({
batteries: firestore.FieldValue.arrayUnion(value)
})
console.log(result);
return result;
} catch (error) {
return error;
}
}
I use try-catch by habit but I don't know if the then...catch is better or not.
As already #windowsill mentioned in his answer, there is no way you can add duplicate elements in an array using client-side code. If your application requires that, then you have to read the entire array, add the duplicates and then write the document back to Firestore.
However, if you want to update an existing element in an array of objects (maps) then you have to use arrayUnion with the entire object. If you want to understand the mechanism better, you can read the following article which is called:
How to update an array of objects in Firestore?
arrayUnion says that it "adds elements to an array but only elements not already present". Maybe it does a stringify or something to check equality and therefore doesn't add the new element. I think you'll have to 1. get the current list, 2. add your element, 3. set the batteries field to the updated list.
I know this may seem like a generic question but I have done research and it didn't seem to work. I'm making a discord bot and I'm new to this kind of thing. I keep getting this error UnhandledPromiseRejectionWarning: MongoError: E11000 duplicate key error collection: Data.users index
This is the code I used:
user.findOneAndUpdate({_id: msg.author, gold: 5});
What is the reason of this problem and how to fix it?
The documentation descibes very clearly what the parameters are:
first parameter: filter
second parameter: update
third parameter: settings object
In our case, you pass a single object, which is interpreted as the filter. You need to pass two objects:
user.findOneAndUpdate({_id: msg.author}, {gold: 5});
This specifies that you want to update gold to 5 for the first record whose _id equals msg.author.
See more examples here: https://mongoosejs.com/docs/tutorials/findoneandupdate.html
Note, that this answer assumes that you have an _id field. If it has a different name, then use that instead.
mongoose .findOneAndUpdate() expects 2 parameters:
the _id of the document you'd update
the new data of the document
So, your code should be this way instead:
user.findOneAndUpdate({ _id: msg.author}, {gold: 5});
I have a firestore firebase database , in which I have a collection users
there is an array in the collection and in the array there is a map
in map there is a field qty.. I want to increment that qty value..
using increment doesnt help as the qty is inside a array index
db.collection("users").doc(checkId).update({
myCart: firebase.firestore.FieldValue.arrayUnion({
qty: firebase.firestore.FieldValue.increment(1),
}),
this is the error Output =>
Uncaught (in promise) FirebaseError: Function FieldValue.arrayUnion() called with invalid data. FieldValue.increment() can only be used with update() and set()
My answer below won't work, given that the qty is in an array. The only way to update an item in an array is to read the entire document, update the item in the array, and then write the entire array with the updated item back to the document.
An alternative would be to use a map instead of an array, and then update the qty using the approach outlined in my (old, and non-working) answer below 👇
You need to specify the full path to the field you're trying to update. So I think in your case, that'll be:
db.collection("users").doc(checkId).update({
"myCart.0.qty": firebase.firestore.FieldValue.increment(1)
}),
The field you want to update is embedded in an array. In this case, you can't use FieldValue.increment(), since it's not possible to call out an array element as a named field value.
What you'll have to do instead is read the entire document, modify the field in memory to contain what you want, and update the field back into the document. Also consider using a transaction for this if you need to update to be atomic.
(If the field wasn't part of an array, you could use FieldValue.increment().)
As of today (29-04-2020)... this is tested by me.
Suppose my data structure is like this:
collection: Users
Any document: say jdfhjksdhfw
It has a map like below
map name: UserPageVisits
map fields: field1,field2,field3 etc
Now we can increment the number field in the map like below:
mapname.field1 etc...
That is use the dot operator to access the fields inside the map just like you would do to an object of javascript.
JAVA Code (Android), update the field using transactions so they can complete atomically.
transaction.update(<documentreference object>,"UserPageVisits.field1",FieldValue.increment(1));
I have just pushed a version of my app which uses this concept and it's working.
Kudos !!
My Best Regards
Previous answers helped me as well, but dont forget about the "merge" property!!! Otherwise it will overwrite your entire array, losing other fields.
var myIndex = 0;
const userRef = db.collection('users').doc(checkId);
return userRef.update({
'myCart.${myIndex}.qty': admin.firestore.FieldValue.increment(1)
}, {
merge: true
});
There are plenty of $addToSet topics out there, but after an hour of searching I still don't know how to evaluate in meteor-serverside-javascript-code if $addToSet added a new element to an array or it was a duplicate match.
The closest one I found was How to check if Mongo's $addToSet was a duplicate or not, but I don't know how to get a db object within meteor.
As written in other posts, the callback-function as a last parameter of the update method always returns 1 and it's always successful, no matter it's a duplicate or distinct element.
If there is no solution currently, I would like to know if there are other ways of checking a nested array (inside one specific collection) for a specific element. A simple true/false result information would be enough.
EDIT:
Ok, I managed to get the Bulk Update working now with the following lines:
var db = MongoInternals.defaultRemoteCollectionDriver().mongo.db;
var col = db.collection("posts");
var batch = col.initializeOrderedBulkOp();
batch.find({_id: postid}).upsert().updateOne({"$addToSet": ...});
batch.execute(function(err, result) {
if (err) throw err;
console.log("RESULT: ", JSON.stringify(result));
//db.close();
});</code>
The $addToSet works with this implementation, but the result object returned from the execution, still, is always the same:
RESULT: {
"ok":1,
"writeErrors":[],
"writeConcernErrors":[],
"nInserted":0,
"nUpserted":0,
"nMatched":1,
"nModified":null,
"nRemoved":0,
"upserted":[]
}
The interesting value nModified stays null both for an update and (duplicate found) skip.
Any ideas?
If I re-phrase the question, you're trying to figure if what you're about to insert is already there.
Why not simply query the object for it before attempting to insert?
If you have a set (array) you can simply do
db.collection.find({array_key: object_to_find_in_array})
and see if it returns an object or nothing. Then update as necessary.
I have an IndexedDB of changes. I add an item like this, and then log the result to check the key has been created successfully:
_this._idb.add('steps', step).done(function (items) {
var item = items[0];
_logger.log("ADDED STEP", { id: item.__id__, step: item }, "CT");
});
The output from this is as expected:
...as you can see, the id has been added to the object when it is stored.
However, when I query the db to getback a list of objects, using this code:
this._idb.steps.query('timestamp').bound(start, end).execute().done(function (results) {
_logger.log("Results", results, "CT");
}
I don't get the id as part of the object that is returned:
... and the lack of id makes updating and deleting impossible.
How can I get the id of the item when I query indexed db using db.js - or am I approaching this in the wrong way, and is there something else I should be doing?
(Note: I'm using TypeScript to compile the JS, but I don't think that's especially relevant to this question)
This is expected behaviour, you're only going to get the __id__ property if you don't define a keyPath in your db schema.
Because there's no keyPath defined the value is not associated with it in indexeddb, it's only added to the resulting object after it has been added, because at that point in time we know the auto-incremented value that IndexedDB has assigned to it.
Since the value isn't really part of the object I don't have any way to assign it to the object when it comes out during a query, maybe I could use the position in the array but that's more likely to be wrong than right.
If you want the ID to be persisted against the object then you need to define a keyPath as part of the object store schema and the property will be added to the resulting object and available and it will be on the object returned from a query.
Disclaimer - I wrote db.js
Looking at the source, __id__ is only defined when your keyPath is null in the add() method. From what I'm seeing, you'll never see this in a query() response.
In IDB null keyPaths are allowed only when using auto-incrementing ("out-of-line") keys. So if you're getting the object back, it should have an auto-incrementing key on it or some other keyPath.
The __ prefix in JavaScript usually means the developer intended it to be a "private" property. I'm guessing this is for internal use and you shouldn't be counting on this in your application code.
Consider using explicit, so-called "in-line" keys on your object store.
The goal of db.js is easy and simple to use. Your is advanced use case.