I need to update the current user and refetch every time the App launches so that I can grasp the most updated version of user object instead of using the one cached on the disk.
User.current()?.fetchInBackground(block: { (user, error) in
//simply using a fetchInBackground won't fetch the entire reference field store in
// the user collection. In the case of using PFQuery, we could simply include the key for
// reference field.
})
Do I have to do extra fetches for all those reference field and then update the current user's filed correspondingly?
Fetch only returns the data that is stored in your database. For a pointer, that is just a basic JSON object specifying it's a pointer, the class name, and the objectId of that object. In order to return this data, you'll instead want to use a Parse Query and include the field that you want. Include works with dot notation, so you could do something like objectAQuery.include("objectB.objectC") which will include all of the data of objectC stored as a pointer on objectB. That will not include all of objectB's data, if I'm not mistaken, though I can't say with certainty.
Finally, use query.get() to get an object with a specific objectId. This will throw an error if the object does not exist, though, so make sure you handle that appropriately. You could also use query equalTo on the objectId then call query.first(), but get would be more recommended.
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 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
I'm integrating GraphQL into my application and trying to figure out if this scenario is possible.
I have a schema for a Record type and a query that returns a list of Records from my service. Schema looks something like:
type Query {
records(someQueryParam: String!): [Record]!
}
type Record {
id: String!
otherId: String!
<other fields here>
}
There are some places in my application where I need to access a Record using the otherId value (because that's all I have access to). Currently, I do that with a mapping of otherId to id values that's populated after all the Records are downloaded. I use the map to go from otherId to id, and then use the id value to index into the collection of Record objects, to avoid iterating through the whole thing. (This collection used to be populated using a separate REST call, before I started using Apollo GQL.)
I'd like to remove my dependency on this mapping if possible. Since the Records are all in the Apollo cache once they've been loaded, I'd like to just query the cache for the Record in question using the otherId value. My service doesn't currently have that kind of lookup, so I don't have an existing query that I can cache in parallel. (i.e. there's no getIdFromOtherId).
tl;dr: Can I query my Apollo cache using something other than the id of an object?
You can't query the cache by otherId for the same reason you don't want to have to search through the record set to find the matching item -- the id is part of the item's key, and without the key Apollo can't directly access the item. Apollo's default cache is a key-value store, not a database that you can query however you like.
It's probably necessary to build a query into your data source that allows mapping between otherId and id, obviously it would be horribly inefficient at scale to search through the entire record set for your item.
Trying to save a Dictionary as a field on a ParseUser object, but its not working. Its a pretty straightforward:
//updateDict does implement IDictionary<string,T>
ParseUser.CurrentUser["ItemsStatus"]= updateDict;
ParseUser.CurrentUser.SaveAsync()
I've already checked to see if my dictionary has values, and I can save the user without issue if I remove the update to the dictionary field. But if I try to add that value I just get a 400 Bad Request "Other Cause" response from parse when I call the save task. Any thoughts?
A dictionary is not a valid Parse data type.
You need to either add the elements of the dictionary to the User object individually or create a new Parse object with the elements from updateDict and create a relation to that.
I am using Sql tables without rowversion or timestamp. However, I need to use Linq to update certain values in the table. Since Linq cannot know which values to update, I am using a second DataContext to retrieve the current object from database and use both the database and the actual object as Input for the Attach method like so:
Public Sub SaveCustomer(ByVal cust As Customer)
Using dc As New AppDataContext()
If (cust.Id > 0) Then
Dim tempCust As Customer = Nothing
Using dc2 As New AppDataContext()
tempCust = dc2.Customers.Single(Function(c) c.Id = cust.Id)
End Using
dc.Customers.Attach(cust, tempCust)
Else
dc.Customers.InsertOnSubmit(cust)
End If
dc.SubmitChanges()
End Using
End Sub
While this does work, I have a problem though: I am also using StoredProcedures to update some fields of Customer at certain times. Now imagine the following workflow:
Get customer from database
Set a customer field to a new value
Use a stored procedure to update another customer field
Call SaveCustomer
What happens now, is, that the SaveCustomer method retrieves the current object from the database which does not contain the value set in code, but DOES contain the value set by the stored procedure. When attaching this with the actual object and then submit, it will update the value set in code also in the database and ... tadaaaa... set the other one to NULL, since the actual object does not contain the changed made by the stored procedure.
Was that understandable?
Is there any best practice to solve this problem?
If you make changes behind the back of the ORM, and don't use concurrency checking - then you are going to have problems. You don't show what you did in step "3", but IMO you should update the object model to reflect these changes, perhaps using OUTPUT TSQL paramaters. Or; stick to object-oriented.
Of course, doing anything without concurrency checking is a good way to lose data - so my preferred option is simply "add a rowversion". Otherwise, you could perhaps read the updated object out and merge things... somehow guessing what the right data is...
If you're going to disconnect your object from one context and use another one for the update, you need to either retain the original object, use a row version, or implement some sort of hashing routine in your database and retain the hash as part of your object. Of these, I highly recommend the Rowversion option as well. Using the current value as the original value like you are trying to do is only asking for concurrency problems.