This question already has an answer here:
Get last created document in a Firebase Firestore collection
(1 answer)
Closed 2 years ago.
i have many document inside a collection of firebase. But i want to retrieve only the last document which is present at the bottom. You can see the image . i want to retrieve the highlighted document
You can use last in following way to get last document.
Firestore.instance.collection("data").snapshots().last
This will give you only last element.
Related
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Firebase Firestore: Is there a way to enforce required fields for all documents in a collection?
(3 answers)
Closed 2 years ago.
I'm creating a Firestore Database that has a "devices" collection then each device has its own document. I already have a device with various fields.
Is there any way I can create a template where the document fields remains the same for all documents and I can just fill in the values upon adding a new device from the Firebase console?
Documents in Firestore only contain exactly what you put in there. There are no "default" or "understood" fields. If you want a document field to contain some value, you will have to write it into each document.
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Can Firestore update multiple documents matching a condition, using one query?
(8 answers)
Updating documents in Cloud Firestore based on a query
(2 answers)
Closed 2 years ago.
i need to update a field in some documents of my users collection, after another document changes, only if those users meet a required criteria. I know i can do querys filtering for the criteria but this would download the documents (i dont need this) i just need to update the field changed in the first document.
is this even posible or should i look for another aproach?
You must know the full path of every document in order to update it. There is equivalent of SQL's "update where" type queries that will both query and update the matching rows. You will need to query first, iterate the results, and update what you need from that set.
This question already has an answer here:
Firestore billing for writes that have no effect [duplicate]
(1 answer)
Closed 2 years ago.
If I update a document with the same content as the existing one, will it count as a write even if it doesn't change anything to the current document's content?
In other words, does Firestore update the document without checking the values of each key inside the document?
If I update a document with the same content as the existing one, will it count as a write even if it doesn't change anything to the current document's content?
Yes, it does.
In other words, does Firestore update the document without checking the values of each key inside the document?
Yes, it does update, it overwrites the entire document, no matter if is the same or not. Firestore doesn't have a mechanism to check if the document is the same. You should check that out.
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How to get a list of document IDs in a collection Cloud Firestore?
(4 answers)
Closed 5 years ago.
Is it possible to get only documents name as a String array without retrieving any collections? I couldn't find any documentation about it.
There is no API to retrieve only the document names in the SDKs. But the REST API has a list call that seems to do precisely that.
This question already has answers here:
Firestore query documents with only collections inside
(2 answers)
Closed 5 years ago.
Is there any naming convention for document id in FireStore. I created some documents inside a collection with the date in "yyyy-mm-dd" as the id. When i try to get all documents inside the collection i got the snapshot size as zero. When I put a dummy doc with test as id I got only the test doc not the other docs.
My document structure
The contraints can be seen here Quotas and Limits if you scroll down to the bottom you will find contraints on ids, paths and field names.