I have been trying to figure out a way to query a list of documents where I have a range filter on one field and order by another field which of course isn't possible, see my other question: Order by timestamp with range filter on different field Swift Firestore
But is it possible to save documents with the timestamp as id and then it would sort by default? Or maybe hardcode an ID, then retrieve the last created document id and increase id by one for the next post to be uploaded?
This shows how the documents is ordered in the collection
Any ideas how to store documents so they are ordered by created at in the collection?
It will order by document ID (ascending) by default in Swift.
You can use .order(by: '__id__') but the better/documented way is with FieldPath documentID() I don't really know Swift but I assume that it's something like...
.order(by: FirebaseFirestore.FieldPath.documentID())
JavaScript too has an internal variable which simply returns __id__.
.orderBy(firebase.firestore.FieldPath.documentId())
Interestingly enough __name__ also works, but that sorts the whole path, including the collection name (and also the id of course).
If I correctly understood your need, by doing the following you should get the correct order:
For each document, add a specific field of type number, called for example sortNbr and assign as value a timestamp you calculate (e.g. the epoch time, see Get Unix Epoch Time in Swift)
Then build a query sorted on this field value, like:
let docRef = db.collection("xxxx")
docRef.order(by: "sortNbr")
See the doc here: https://firebase.google.com/docs/firestore/query-data/order-limit-data
Yes, you can do this.
By default, a query retrieves all documents that satisfy the query in
ascending order by document ID.
See the docs here: https://firebase.google.com/docs/firestore/query-data/order-limit-data
So if you find a way to use a timestamp or other primary key value where the ascending lexicographical ordering is what you want, you can filter by any fields and still have the results sorted by the primary key, ascending.
Be careful to zero-pad your numbers to the maximum precision if using a numeric key like seconds since epoch or an integer sequence. 10 is lexicographical less than 2, but 10 is greater than 02.
Using ISO formatted YYYY-mm-ddTHH:MM:SS date-time strings would work, because they sort naturally in ascending order.
The order of the documents shown in the Firebase console is mostly irrelevant to the functioning of your code that uses Firestore. The console is just for browsing data, and that sorting scheme makes it relatively intuitive to find a document you might be looking for, if you know its ID. You can't change this sort order in the console.
Your code is obviously going to have other requirements, and those requirements should be coded into your queries, without regarding any sort order you see in the dashboard. If you want time-based ordering of your documents, you'll have to store some sort of timestamp field in the document, and use that for ordering. I don't recommend using the timestamp as the ID of a document, as that could cause problems for you in the future.
Related
How can I filter the results on the Firestore Console by a timestamp field?
On the collection users, we have a field createdOn of type timestamp. If I want to filter the collection by field, I get the following dialog
I have tried entering the date as string
2019-09-15
2019-09-15T00:00:00Z
I have also tried using a timestamp as number in millis and seconds
1568505600000
1568505600
When looking at the requests sent to Firestore, the structured query uses a field filter with a value of corresponding to either stringValue or integerValue, but I think the timestampValue would be the right thing.
I do not want to adapt the query in the console and build my own requests. I know that there is always the option to sort the documents in the collection and then scroll to where it's interesting, but this will load all documents that are not relevant.
Is there a simple way to do what I want?
There is a new query builder tab in the console (I do not know when this was introduced, but I assume during the Firebase Summit 2022). For the query above, this would look like this
It even has a timestamp type in the select list.
I'm using this php package to make queries - https://github.com/jenssegers/laravel-mongodb
The situation is, there are two fields, user_id and post_status among others. I want to retrieve all the documents in that collection, but when post_status field value is draft, that should be retrieved only when user_id is a given string. The idea is, only logged in user finds their drafted posts among other posts.
I'm having hard time finding any solution for this problem. The app is still not in production. If I should store data is some different manner, that is an option as well.
Find documents with a certain field value only when another field value is a given string
The question your are framing is simply convert into a and query, how let's see it
when another field value is a given string
This means that you have some result sets and you need to filter out when user_id match with some string. i.e some result sets and user_id = <id>
Now consider the first part of the sentence Find documents with a certain field value
This means you are filtering the records with some values i.e "status" = "draft" and whatever result will come and want again to filter on the basis of user_id = <id>
So finally you will end-up with below query:
db.collectionName.find({"status":"draft", "user_id": "5c618615903aaa496d129d90"})
Hope this explanation will help you out or you can rephrase your question I will try to modify by ans.
Why do we when the created_at field when the timestamp can be found in the first 4 bytes of the ObjectId
ObjectId("5349b4ddd2781d08c09890f4").getTimestamp()
Taken from MongoDB Docs
There are several cases where it makes sense to do so:
When you need better precision - ObjectId.getTimestamp() is precise up to seconds, while Date fields store milliseconds. Compare this in mongo shell: new Date() yields ISODate("2016-01-03T21:21:38.032Z"), while ObjectId().getTimestamp() yields ISODate("2016-01-03T21:21:50Z").
When you are not using ObjectId at all - it is often taken as a given that _id field should be populated with ObjectId, while in fact ObjectId is only a default used by most of the drivers and MongoDB itself doesn't impose it - on the contrary, it is encouraged to use any "natural" unique ID if it exists for the documents. In this case though you will have to store "creation timestamp" yourself if you need it.
Usability - if you rely on the presence of this field and the data in it, it might be better, at least from design standpoint, to be explicit about it. This is more a matter of taste though. However, as noted in comments, if you also want to filter or sort by "creation timestamp" - it will be easier to do having a dedicated field for it and using query operators like $gt, for example, directly on it.
As you said, like it states clearly in the documentation:
Since the _id ObjectId by default stores the 4 byte timestamp, in most cases you do not need to store the creation time of any document.
And you may use ObjectId("5349b4ddd2781d08c09890f4").getTimestamp() in order to get the creation date in ISO date format.
It is also a matter of convenience to the costumer (us) to have a service like that, as it makes our attempt of getting the creating date and performing actions on it much more intuitive and easy.
I would like to store and query documents that contain a from-to date range, where the range represents an interval when the document has been valid.
Typical use cases in lucene/solr documentation address the opposite problem: Querying for documents that contain a single timestamp and this timestamp is contained in a date range provided as query parameter. (createdate:[1976-03-06T23:59:59.999Z TO *])
I want to use the edismax parser.
I have found the ms() function, which seems to me to be designed for boosting score only, not to eliminate non-matching results entirely.
I have found the article Spatial Search Tricks for People Who Don't Have Spatial Data, where the problem described by me is said to be Easy... (Find People Alive On May 25, 1977).
Is there any simpler way to express something like
date_from_query:[valid_from_field TO valid_to_field] than using the spacial approach?
The most direct approach is to create the bounds yourself:
valid_from_field:[* TO date_from_query] AND valid_to_field:[date_from_query TO *]
.. which would give you documents where the valid_from_field is earlier than the date you're querying, and the valid_to_field is later than the date you're querying, in effect, extracting the interval contained between valid_from_field and valid_to_field. This assumes that neither field is multi valued.
I'd probably add it as a filter query, since you don't need any scoring from it, and you probably want to allow other search queries at the same time.
I have a collection of data and I want to get it sorted by insertion time. I have not any additional fields to store the insert time. But as I found out I can get this time from Id.
I have tried this code:
return bookmarks.find({}, {sort: {_id.getTimestamp(): 1}, limit: 10});
or
return bookmarks.find({}, {sort: {ObjectId(_id).getTimestamp(): 1}, limit: 10});
but get the error message:
=> Your application has errors. Waiting for file change.
Is there any way to sort collection by insertion datetime using only id field ?
At the moment this isn't possible with Meteor, even if it is with MongoDB. The ObjectID's created with meteor don't bear a timestamp. See http://docs.meteor.com/#collection_object_id
The reason for this is client side code can insert code and it can arrive late on the server, hence there is no guarantee the timestamp portion of the ObjectID will be accurate. In addition to the latency the client side's date is used meaning if they're off it's going to get you incorrect data. I think this is the reason they use an ObjectID but it is completely random.
If you want to sort by date you have to store the time/date separately.
The part what i striked out is not accurate. Meteor use it is own id generation which is based on a random string that is while does not apply the doc what i linked before. Check sasha.sochka's comment under.
It is nearly but not 100% good if you just sort for the _id field . While as it is constructed the first 4 byte is the timestamp in secs (so sorting for the getTimestamps value is not better). Under one second resolution you cannot get the exact order, as it is mentioned in the documentation: http://docs.mongodb.org/manual/reference/object-id/#objectid
It is still true that you can try to check the exact order of the insert/update ops against your collection in the oplog, if you have an oplog, but as it is a capped collection anyway you will see the recent operations only. http://docs.mongodb.org/manual/core/replica-set-oplog/.