I would like to know, how to save related documents in reactive mongo ?. Because I find a code that attempts to do the magic... But when it should save the related document in another collection, it serializes inside the "father" of the relationship let say... I know that in spring data reactive mongo, #DbRef doesnt have support... How could I save the data in a way that, if I query the collection, I see that the attributesare the name of the collection and the generated id instead all of the object attributes ?.
If the pic above is seen, you will see that the attribute "user" is saved as a nested document but not in the corresponding collection. Do I need to hook in another event ?.
I had put a listener onbeforeconvert to scan every time a save operation is to be applied and save the object... How to proceed ?... think I should verify if it has a related doc from another collection and if its nonnull... If the object doesnt have any attr l
Alike, then save it... if not continue the scanning... dunno
Related
I am working on a spring application.
We have a specific requirement where when we get a specific event, we want to look it up in the DB. If we find the record in the DB, then we delete it from DB, create another event using the details and trigger it.
Now my concern is:
I do not want to use two different calls, one to find the record and another to
delete the record.
I am looking for a way where we can delete the record using a custom
query and simultaneously fetch the deleted record.
This saves two differnet calls to DB, one for fetch and another for delete.
What I found on the internet so far:
We can use the custom query for deletion using the annotation called #Modifying. But this does not allow us to return the object as a whole. You can only return void or int from the methods that are annotated using #Modifying.
We have removeBy or deleteBy named queries provided by spring. but this also returns int only and not the complete record object that is being deleted.
I am specifically looking for something like:
#Transactional
FulfilmentAcknowledgement deleteByEntityIdAndItemIdAndFulfilmentIdAndType(#Param(value = "entityId") String entityId, #Param(value = "itemId") String itemId,
#Param(value = "fulfilmentId") Long fulfilmentId, #Param(value = "type") String type);
Is it possible to get the deleted record from DB and make the above call work?
I could not find a way to retrieve the actual object being deleted either by custom #Query or by named queries. The only method that returns the object being deleted is deleteById or removeById, but for that, we need the primary key of the record that is being deleted. It is not always possible to have that primary key with us.
So far, the best way that I found to do this was:
Fetch the record from DB using the custom query.
Delete the record from DB by calling deleteById. Although, you can now delete it using any method since we would not be requiring the object being returned by deleteById. I still chose deleteById because my DB is indexed on the primary key and it is faster to delete it using that.
We can use reactor or executor service to run the processes asynchronously and parallelly.
I'm trying to find a way to save a new object if one like it doesn't already exist with a specified custom ID.
I basically need to refresh a whole bunch of data every day but each item has its own ID set somewhere else (so not a parse objectId). I therefore can't use something like the standard save function as it'll just make a new record every time.
I've thought of trying to set the objectId of an object when its first created in the DB but I can't seem to do that... (Half expected this).
I've also thought of doing the obvious - checking if an object exists using a normal query but with a few thousand objects to compare, this will be very inefficient.
Any suggestions?
Maybe there is a save function or variation where its kind of "save or create depending if an object exists with this value in this field" :)
Thank you!
PS. I'm writing this within a Cloud Job - so JavaScript
I use Entity Framework in combination with an Oracle database. If I create a query like
myLinqStatement.ToListAsync()
I get wrong data returned as a result. If I change the statement to
myLinqStatement.AsNoTracking.ToListAsync()
I get the correct data.
I also checked the native SQL query, which is generated by myLinqStatement.ToListAsync(). The generated SQL query is correct, because I get the correct data.
So is there a problem in the mapping? And why is it working with AsNoTracking?
Thanks!
What AsNoTracking does is to retrieve the data without attaching it to the context, hence any changes you apply over the data do not take effect unless you attach it again so that EF knows it should track its changes.
The code snippets you've provided do not show the whole picture, from the moment a context is created, but is it possible that other parts of your code mutate data before you call myLinqStatement.ToListAsync()?
As you mention that myLinqStatement.AsNoTracking.ToListAsync() returns expected data, makes me assume that there are some side effects in your code that AsNoTracking simply is not aware so just returns whatever it finds in your db
I came across this question because I had a similar issue with Entity Framework Core querying a DB view, the issue was cause because view didn't have a key defined, after defining a key for the entity that map to that DB view, the query returned the same result in both cases (using AsNoTracking or without using it).
In T-SQL a key for a DB view can be defined this way:
CREATE UNIQUE CLUSTERED INDEX UQ_MyDBViewName_ColumnKey
ON dbo.MyDBViewName (ColumnKey);
And in code, you can map the key using the [Key] attribute in the corresponding property of the entity or using the EF fluent API. It will depend of what the project is using.
Either way, using AsNoTracking on a query that goes directly to a DB view makes a lot of sense. Also, if for some reason the query of the view does not allow us to define a key for that view, then the option is to use AsNoTracking.
Hope it helps anyone else having the same issue.
So i don't know the type of an document I want retrieve and thus have no idea how to retrieve this document in a doctrine manner.
Normally i would do somethink like that:
$dm->find('User', 12345);
And i should get the User class.
But what if I don't know the type of the document? It's stored in document so Doctrine should figure it out. I should simple call
$dm->find(12345); //of course this doesn't work
and Doctrine should look into "type" field in the document and return the User class.
Of course i can do it by hand but maybe there is an Doctrine method for this problem?
So my question is: How to retrieve (using doctrine) the document and instantiate correct class (depending on the "type" field found in the document)?
I think normally you would want to develop a view for each logical type of data that you want to look at, wherever it is in the document graph.
Otherwise you could write a view that looks at every document, looping through every property recursively, and find the value 12345, but that of course would, probably, be very slow.
The views can look at your type property (which is duck typing) and emit() the correct object.
I need to convert a Session object to an IOrderedQueryable and came up blank. I've thought of creating a wrapper, but its not working properly. Basically, I am pulling a Linq query and would like to store it so that I don't have to pull it each time I visit. There are up to 7-10 parameters per user so it's not something that's great for caching.
I can simply cast my Session object as an IOrderedQueryable like:
(IOrderedQueryable<T>)Session["myObject"];
It seems you want to store the data returned by the linq query, if that's the case you need to make it grab the data i.e. by using .ToList() and storing that.