This simple logic I want to take a mono locality object from AddressRepository and if the locality exist it will update else new record will be added into locality table.
As I am very new to spring reactive programming, I am little confuse about the implementation. I have written following code segments.
Address address = new Address();
// If locality getByName == true -> Update
this.addressRepository.findByName(addressCommand.getLocality())
.convert().with(toMono())
.subscribe(item -> {
if(item.getLocalityName().equalsIgnoreCase(addressCommand.getLocality())){
address.setLocality(item);
}else{
address.setLocality(Locality.builder()
.localityName(addressCommand.getLocality()).build());
}
});
In the same method I have another where set the above address and return user Id to client.
Mono<User> createdUser = this.userRepository.adminCreate(
User.builder()
.address(address)
.administrativeArea(administrativeArea)
.build()
)
.convert().with(toMono());
return createdUser.map(u -> u.getCustomerId().toString());
If I execute this in debug mode and if I put debug points I can see user data setting doing first and after some time address setting happening. So always locality data will be null. I wonder can I do this within same pipeline or any suggestions?
Thanks,
Dasun.
Related
So I have a Apache Camel route that reads Data elements from a JPA endpoint, converts them to DataConverted elements and stores them into a different database via a second JPA endpoint. Both endpoints are Oracle databases.
Now I want to set a flag on the original Data element that it got copied successfully. What is the best way to achieve that?
I tried it like that: saving the ID in the context and then reading it and accessing a dao method in the .onCompletion().onCompleteOnly().
from("jpa://Data")
.onCompletion().onCompleteOnly().process(ex -> {
var id = Long.valueOf(getContext().getGlobalOption("id"));
myDao().setFlag(id);
}).end()
.process(ex -> {
Data data = ex.getIn().getBody(Data.class);
DataConverted dataConverted = convertData(data);
ex.getMessage().setBody(data);
var globalOptions = getContext().getGlobalOptions();
globalOptions.put("id", data.getId().toString());
getContext().setGlobalOptions(globalOptions);
})
.to("jpa://DataConverted").end();
However, this seems to trigger a deadlock, the dao method is stalling on the commit of the update. The only explanation could be that the Data object gets locked by Camel and is still locked in the .onCompletion().onCompleteOnly() part of the route, therefore it can't get updated there.
Is there a better way to do it?
Have you tried using the recipient list EIP where first destination is the jpa:DataConverted endpoint and the second destination will be the endpoint to set the flag. This way both get the same message and will be executed sequentially.
https://camel.apache.org/components/3.17.x/eips/recipientList-eip.html
from("jpa://Data")
.process(ex -> {
Data data = ex.getIn().getBody(Data.class);
DataConverted dataConverted = convertData(data);
ex.getIn().setBody(data);
})
.recipientList(constant("direct:DataConverted","direct:updateFlag"))
.end();
from("direct:DataConverted")
.to("jpa://DataConverted")
.end();
from("direct:updateFlag")
.process(ex -> {
var id = ((MessageConverted) ex.getIn().getBody()).getId();
myDao().setFlag(id);
})
.end();
Keep in mind, you might want to make the route transactional by adding .transacted()
https://camel.apache.org/components/3.17.x/eips/transactional-client.html
I want to be able to extract the List<Payload> from the Mono<List<Payload>> to pass it to a downstream service for processing (or maybe return from the read(RequestParams params) method, instead of it returning void):
#PostMapping("/subset")
public void read(#RequestBody RequestParams params){
Mono<List<Payload>> result = reader.read(params.getDate(), params.getAssetClasses(), params.getFirmAccounts(), params.getUserId(), params.getPassword());
....
}
where reader.read(...) is a method on an autowired Spring service utilizing a webClient to get the data from external web service API:
public Mono<List<Payload>> read(String date, String assetClasses, String firmAccounts, String id, String password) {
Flux<Payload> nodes = client
.get()
.uri(uriBuilder -> uriBuilder
.path("/api/subset")
.queryParam("payloads", true)
.queryParam("date", date)
.queryParam("assetClasses", assetClasses)
.queryParam("firmAccounts", firmAccounts)
.build())
.headers(header -> header.setBasicAuth("abc123", "XXXXXXX"))
.retrieve()
.onStatus(HttpStatus::is4xxClientError, response -> {
System.out.println("4xx error");
return Mono.error(new RuntimeException("4xx"));
})
.onStatus(HttpStatus::is5xxServerError, response -> {
System.out.println("5xx error");
return Mono.error(new RuntimeException("5xx"));
})
.bodyToFlux(Payload.class);
Mono<List<Payload>> records = nodes
.collectList();
return records;
}
Doing a blocking result.block() is not allowed in WebFlux and throws an exception:
new IllegalStateException("block()/blockFirst()/blockLast() are blocking, which is not supported in thread ..." ;
What is a proper way to extract the contents of a Mono in WebFlux?
Is it some kind of a subscribe()? What would be the syntax?
Thank you in advance.
There is no "proper way" and that is the entire point. To get the value you need to block, and blocking is bad in webflux for many reasons (that I won't go into right now).
What you should do is to return the publisher all the way out to the calling client.
One of the things that many usually have a hard time understanding is that webflux works with a producer (Mono or Flux) and a subscriber.
Your entire service is also a producer, and the calling client can be seen as the subscriber.
Think of it as a long chain, that starts at the datasource, and ends up in the client showing the data.
A simple rule of thumb is that whomever is the final consumer of the data is the subscriber, everyone else is a producer.
So in your case, you just return the Mono<List<T> out to the calling client.
#PostMapping("/subset")
public Mono<List<Payload>> read(#RequestBody RequestParams params){
Mono<List<Payload>> result = reader.read(params.getDate(), params.getAssetClasses(), params.getFirmAccounts(), params.getUserId(), params.getPassword());
return result;
}
While the following does return the value of the Mono observable in the logs:
#PostMapping("/subset")
#ResponseBody
public Mono<ResponseEntity<List<Payload>>> read1(#RequestBody RequestParams params){
Mono<List<Payload>> result = reader.read(params.getDate(), params.getAssetClasses(), params.getFirmAccounts(), params.getUserId(), params.getPassword());
return result
.map(e -> new ResponseEntity<List<PayloadByStandardBasis>>(e, HttpStatus.OK));
}
the understanding I was seeking was a proper way to compose a chain of calls, with WebFlux, whereby a response from one of its operators/legs (materialized as as a result from a webclient call, producing a set of records, as above) could be passed downstream to another operator/leg to facilitate a side effect of saving those records in a DB, or something to that effect.
It would probably be a good idea to model each of those steps as a separate REST endpoint, and then have another endpoint for a composition operation which internally calls each independent endpoint in the right order, or would other design choices be more preferred?
That is ultimately the understanding I was looking for, so if anyone wants to share an example code as well as opinions to better implement the set of steps described above, I'm willing to accept the most comprehensive answer.
Thank you.
I am trying to build a simple web application using spring boot - webflux (functional endpoints) & jdbc. The app receives payload in XML format (which is some details of 1 employee). Code given below persists data for one employee as expected.
public Mono<String> createData(final Mono<Record> inputMono) {
final String someID = UUID.randomUUID().toString();
final Mono<Integer> asyncUpdate = inputMono.flatMap(record -> {
return beginUpdate(dataSource,
sqlStatementSharedAbove).withStatementEnricher(stmt -> {
stmt.setString(1, record.getFirstName());
stmt.setString(2, record.getLastName());
stmt.setInt(3, record.getAddress());
}).build();
});
return asyncUpdate.doOnSuccess(affectedRows -> LOGGER.debug("Added
{} rows with ID {}", affectedRows, someID))
.map(affectedRows -> someID);
}
Now I need to save similar data for multiple employees (modifying the XML payload to contain multiple employee records)
In non-webflux world, I would just iterate over the list of employee objects and call this function for each one of them.
How can I achieve the same in webflux?
Essentially I am looking to handle a saveAll functionality with webflux and given that I have to work with JDBC (I do understand that JDBC doesn't support non blocking paradigm and Mongo supports a saveAll API but I have certain constraints as to what DB i can use and therefore must make this work with JDBC)
Thank you.
Following code works to save multiple employee records. Essentially it needs a Flux (of Employees) to work with -
public Mono<Void> createData(final Flux<Record> inputFlux) {
return inputFlux.flatMap(record -> {
return beginUpdate(dataSource,
sqlStatementSharedAbove).withStatementEnricher(stmt -> {
stmt.setString(1, record.getFirstName());
stmt.setString(2, record.getLastName());
stmt.setInt(3, record.getAddress());
}).build().doOnSuccess(affectedRows -> LOGGER.info("Added rows{}", affectedRows));
}).then;
}
My application uses BreezeJS, ASP.NET Web API and EF.
I'm trying to save an object using breeze, as follows:
var saveOptions = this.manager.saveOptions.using({ resourceName: "SaveLocationSettings", tag: clientId, allowConcurrentSaves: true });
var obj = self.manager.saveChanges(null, saveOptions).then(saveSucceeded, saveFailed);
I'm using a custom save method on the server side, which returns a SaveResult object. However, on the client side, the entity manager still maintains the modified state.
My controller on the Web API is a BreezeController.
According to the breeze documentation, if your custom method has the signature similar to the Breeze SaveChanges() method, it should work similar to SaveChanges() method. However, if I use the breeze SaveChanges(), the entity state gets updated properly. But my custom endpoint save does not update the entity state, although the data is saved in the database.
UPDATE:
After some investigation, I figured that this happens only with one entity type that goes to this particular save endpoint. Say, I have a 'location' object, with a collection of 'availability' associated with it, as follows:
Class Location {
public Location() {
this.Availabilities = new HashSet<Availability>();
}
}
Now from the client side, if I only change some property of the Location object, it handles the hasChanges property correctly. But if I change the Availability only or Availability along with another property of the location, then the hasChanges is not updated properly on client side.
This is my server side code that's called from the WebAPI controller:
public SaveResult SaveLocation(Location l, List<MaxAvailability> maxAvailability, int changedBy)
{
// Create a SaveResult object
// we need to return a SaveResult object for breeze
var keyMappings = new List<KeyMapping>();
var entities = new List<object> {l, maxAvailability};
var saveResult = new SaveResult() { Entities = entities, KeyMappings = keyMappings, Errors = null };
try
{
if (l.LocationId == -1)
{
// add new location
l.LocationId = this.AddNewLocationWithItsAssociatedData(l, maxAvailability, changedBy);
}
else
{
// do changes to the existing location
this.UpdateExistingLocationWithItsAssociatedData(l, maxAvailability, changedBy);
}
}
catch (DbEntityValidationException ex)
{
// Log the error and add the errors list to SaveResult.
// Retrieve the error messages as a list of strings.
saveResult.Errors = this.GetErrors(ex);
}
return saveResult;
}
I think I figured out the answer. It was due to some bad practice in my code. When modifying the availability of an existing location, instead of updating the existing record, I was deleting the existing record and adding a new one. This was causing the client side availability object and the database object to have two different states. Once it was resolved, the hasChanges() state was behaving as expected.
In my WCF service's business logic, most of the places when I need to locate an entity, I use this syntax:
public void UpdateUser(Guid userId, String notes)
{
using (ProjEntities entities = new ProjEntities())
{
User currUser = entities.SingleOrDefault(us => us.Id == userId);
if (currUser == null)
throw new Exception("User with ID " + userId + " was not found");
}
}
I have recentely discovered that the DbContext has the Find method, and I understand I can now do this:
public void UpdateUser(Guid userId, String notes)
{
using (ProjEntities entities = new ProjEntities())
{
User currUser = entities.Find(userId);
if (currUser == null)
throw new Exception("User with ID " + userId + " was not found");
}
}
Note : the 'userId' property is the primary key for the table.
I read that when using Find method entity framework checks first to see if the entity is already in the local memory, and if so - brings it from there. Otherwise - a trip is made to the database (vs. SingleOrDefault which always makes a trip to the database).
I was wondering if I now will convert all my uses of SingleOrDefault to Find is there any potential of danger?
Is there a chance I could get some old data that has not been updated if I use Find and it fetches the data from memory instead of the database?
What happens if I have the user in memory, and someone changed the user in the database - won't it be a problem if I always use now this 'memory' replica instead of always fetching the latest updated one from the database?
Is there a chance I could get some old data that has not been updated
if I use Find and it fetches the data from memory instead of the
database?
I think you have sort of answered your own question here. Yes, there is a chance that using Find you could end up having an entity returned that is out of sync with your database because your context has a local copy.
There isn't much more anyone can tell you without knowing more about your specific application; do you keep a context alive for a long time or do you open it, do your updates and close it? obviously, the longer you keep your context around the more susceptible you are to retrieving an up to date entity.
I can think of two strategies for dealing with this. The first is outlined above; open your context, do what you need and then dispose of it:
using (var ctx = new MyContext())
{
var entity = ctx.EntitySet.Find(123);
// Do something with your entity here...
ctx.SaveChanges();
}
Secondly, you could retrieve the DbEntityEntry for your entity and use the GetDatabaseValues method to update it with the values from the database. Something like this:
var entity = ctx.EntitySet.Find(123);
// This could be a cached version so ensure it is up to date.
var entry = ctx.Entry(entity);
entry.OriginalValues.SetValues(entry.GetDatabaseValues());