I need to be able to "touch" a document (for optimistic purposes) in ArangoDb in order to check and update the _rev without modifying any other data in the document. I have yet to find a way to do this generically with AQL or Javascript Driver without knowing something about existing data in the document. What am I missing?
Some research and testing points to using AQL like:
LET doc = DOCUMENT(#id)
REPLACE doc IN ##collection OPTIONS { ignoreRevs: false, revision: #revision }
Related
I am working on a node.js app, and I've been searching for a way around using the Model.save() function because I will want to save many documents at the same time, so it would be a waste of network and processing doing it one by one.
I found a way to bulk insert. However, my model has two properties that makes them unique, an ID and a HASH (I am getting this info from an API, so I believe I need these two informations to make a document unique), so, I wanted that if I get an already existing object it would be updated instead of inserted into the schema.
Is there any way to do that? I was reading something about making concurrent calls to save the objects, using Q, however I still think this would generate an unwanted load on the Mongo server, wouldn't it? Does Mongo or Mongoose have a method to bulk insert or update like it does with insert?
Thanks in advance
I think you are looking for the Bulk.find(<query>).upsert().update(<update>) function.
You can use it this way:
bulk = db.yourCollection.initializeUnorderedBulkOp();
for (<your for statement>) {
bulk.find({ID: <your id>, HASH: <your hash>}).upsert().update({<your update fields>});
}
bulk.execute(<your callback>)
For each document, it will look for a document matching the {ID: <your id>, HASH: {your hash}} criteria. Then:
If it finds one, it will update that document using {<your update fields>}
Otherwise, it will create a new document
As you need, it will not make a connection to the mongo server on each iteration of the for loop. Instead a single call will be made on the bulk.execute() line.
So I've been trying to move data from one database to another. I've already move them but I need to clear the documents which I've already moved from the old database. I've been using ektorp's execute bulk to perform bulk operations. But for some reason I keep getting document update conflict when I try to delete bulk by inserting _deleted.
I might be doing it wrong, here is what I did.
Fetch by bulk with include docs. (For some reason, this doesn't work with just id and rev.)
Then include the _deleted field to each document.
Post using executebulk.
It works for some documents but keeps getting document update conflict for some documents.
Any solution/suggestions please..
This is the preferred way of deleting docs in bulk:
List<Object> bulkDocs = ...
MyClass toBeDeleted = ...
bulkDocs.add(BulkDeleteDocument.of(toBeDeleted));
db.executeBulk(bulkDocs);
If you only need a way to delete/update docs in bulk and you don't need to necessarily implement it in your own software, you can use the great couchapp at:
https://github.com/harthur/costco
You need to upload it to your own server with a couchapp deployment tool, and use a function like
function(doc) {
if(doc.istodelete) // replace this or remove to delete all docs
return null;
}
Read instructions and examples
If I call findAndModify, and a document matches the query, but the existing document has fields that the doc does not, will the old fields still exist in the new document, or will they be removed?
I've checked the findAndModify docs and the answers's not obvious. Trying it, fields in the old doc that aren't in the new doc seem to be removed - since this involves losing data, and there's nothing explicit about this is the docs, I'm not sure if this is the expected behaviour or not.
findAndModify behaves exactly like update. This means that the document in the database will be completely replaced by the document you provide, unless you use operators like $set or $push which explicitely modify a document.
By the way: When the node.js-specific documentation is too brief, the description of the analogue command in the general manual is often much more detailed.
I have a Tags collection which contains documents of the following structure:
{
word:"movie", //tag word
count:1 //count of times tag word has been used
}
I am given an array of new tags that need to be added/updated in the Tags collection:
["music","movie","book"]
I can update the counts all Tags currently existing in the tags collection by using the following query:
db.Tags.update({word:{$in:["music","movies","books"]}}, {$inc:{count:1}}), true, true);
While this is an effective strategy to update, I am unable to see which tag values were not found in the collection, and setting the upsert flag to true did not create new documents for the unfound tags.
This is where I am stuck, how should I handle the bulk insert of "new" values into the Tags collection?
Is there any other way I could better utilize the update so that it does upsert the new tag values?
(Note: I am using Node.js with mongoose, solutions using mongoose/node-mongo-native would be nice but not necessary)
Thanks ahead
The concept of using upsert and the $in operator simultaneously is incongruous. This simply will not work as there is no way to different between upsert if *any* in and upsert if *none* in.
In this case, MongoDB is doing the version you don't want it to do. But you can't make it change behaviour.
I would suggest simply issuing three consecutive writes by looping through the array of tags. I know that's it's annoying and it has a bad code smell, but that's just how MongoDB works.
Is it possible to have couch update or change fields on the fly when you create/update a doc? For example in the design view.... validate_doc_update:
function(newDoc, oldDoc, userCtx) {
}
Within that function I can throw errors like:
if(!newDoc.user_email && !newDoc.user_name && !newDoc.user_password){
throw({forbidden : 'all fields required'});
}
My Question is how would I reassign a field? I tried this:
newDoc.user_password ="changed";
with changed being some new value or hashed value. My overall goal is to build a user registration/login system with node and couchdb and have not found very good examples.
The validate_doc_update function cannot have any side effects and cannot change the document before storage. It only has the power to block an update or to let it through. This is important, because the function is not only called when a user requests an update, but also when changes are replicated from one CouchDB instance to another. So the function can be called multiple times for one document.
However, CouchDB now supports Document Update Handlers that can modify a document or even build it from scratch. These can be used to convert non-JSON input data into usable documents. You can find some documentation in the CouchDB Wiki.
Before you build your own user registration/login system, I'd suggest you look into the built-in CouchDB security features (if you haven't - some information here). They might not be enough for you (e.g. if you need email validation or something similar), but maybe you can build on them.