I am new to spring webflux and am trying to perform some arithmetic on the values of two monos. I have a product service that retrieves account information by calling an account service via webClient. I want to determine if the current balance of the account is greater than or equal to the price of the product.
Mono<Account> account = webClientBuilder.build().get().uri("http://account-service/user/accounts/{userId}/",userId)
.retrieve().bodyToMono(Account.class);
//productId is a path variable on method
Mono<Product> product =this.productService.findById(productId);
When I try to block the stream I get an error
block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-2
//Causes Error
Double accountBalance = account.map(a->a.getBalance()).block():
Double productPrice = product.map(p->p.getPrice()).block();
///Find difference, send response accordingly....
Is this the correct approach of there is another, better way to achieve this? I was also thinking something along the lines of:
Mono<Double> accountBalance = account.map(a->a.getBalance()):
Mono<Double> productPrice = product.map(p->p.getPrice());
Mono<Double> res = accountBalance.zipWith(productPrice,(b,p)-> b-p);
//Something after this.....
You can't use block method on main reactor thread. This is forbidden. block may work when publish mono on some other thread but it's not a case.
Basically your approach with zipping two monos is correct. You can create some helper method to do calculation on them. In your case it may look like:
public boolean isAccountBalanceGreater(Account acc, Product prd) {
return acc.getBalance() >= prd.getPrice();
}
And then in your Mono stream you can pass method reference and make it more readable.
Mono<Boolean> result = account.zipWith(productPrice, this::isAccountBalanceGreater)
The question is what you want to do with that information later. If you want return to your controller just true or false that's fine. Otherwise you may need some other mappings, zippings etc.
Update
return account.zipWith(productPrice, this::createResponse);
...
ResponseEntity createResponse(Account acc, Product prd) {
int responseCode = isAccountBalanceGreater(acc, prd) ? 200 : 500;
return ResponseEntity.status(responseCode).body(prd);
}
Related
I'm new with unit tests. I'm trying test Service Layer in a SPRING APP.
Good, i have any relationships in my Service.
VirtualDatacenterModel vdc = vdcRepository.findById(vmDTO.getVdc()).orElseThrow(() -> new ClientException("Invalid VDC id"));
DataCenterModel dc = vdc.getDatacenter();
String vmName = vdc.getTenant().getName() + "_[" + vmDTO.getName() + "]";
In my test i used MOCKITO, dependencies already is mocked, then i cannot see where is wrong
CreateVmDTO vmDTO = Mockito.mock(CreateVmDTO.class);
VmModel vm = Mockito.mock(VmModel.class);
VirtualDatacenterModel vdc = Mockito.mock(VirtualDatacenterModel.class, Mockito.RETURNS_DEEP_STUBS);
TenantModel tenant = Mockito.mock(TenantModel.class);
Mockito.when(vmRepository.save(vm)).thenReturn(new VmModel());
Mockito.when(vdcRepository.findById(vmDTO.getVdc())).thenReturn(Optional.of(new VirtualDatacenterModel()));
Mockito.doReturn(tenant).when(vdc).getTenant();
Mockito.when(vdc.getTenant().getName()).thenReturn("Olivia");
VmModel vmReturn = vmService.createVM(vmDTO);
And i receive NullPointerException, i probably don't know how to use Mockito correctly
You can only mock one action at the time, the following line will certainly be a problem:
Mockito.when(vdcRepository.findById(vmDTO.getVdc())).thenReturn(Optional.of(new VirtualDatacenterModel()));
cause vmDTO.getVdc() will return a null pointer. (vmDTO is a mocked object itself, and has no instruction set for that call). Assuming vmDTO.getVdc() returns the vdc, you can fix as follows:
CreateVmDTO vmDTO = Mockito.mock(CreateVmDTO.class);
VmModel vm = Mockito.mock(VmModel.class);
VirtualDatacenterModel vdc = Mockito.mock(VirtualDatacenterModel.class, Mockito.RETURNS_DEEP_STUBS);
//example fix:
Mockito.when(vmDTO.getVdc()).thenReturn(vdc);
TenantModel tenant = Mockito.mock(TenantModel.class);
Mockito.when(vmRepository.save(vm)).thenReturn(new VmModel());
//also you can do directly:
Mockito.when(vdcRepository.findById(vdc)).thenReturn(Optional.of(new VirtualDatacenterModel()));
Mockito.doReturn(tenant).when(vdc).getTenant();
Mockito.when(vdc.getTenant().getName()).thenReturn("Olivia");
VmModel vmReturn = vmService.createVM(vmDTO);
Also the naming of your methods throws me off:
You have a method vdcRepository.findById, but your input is a vdc object, and not an id? Either the naming is confusing or your input is wrong. If getVdc returns an Id, then you can fix the code by mocking the return of an Id (rename the method to getVdcId or something).
Note: Personally, I seldom mock a DTO. It is just as easy to make the real DTO object, since they often come with a builder or getter/setter.
I am trying to get live updates on my redis ordered list without success.
It seems like it fetches all the items and just ends on the last item.
I would like the client to keep get updates upon a new order in my ordered list.
What am I missing?
This is my code:
#RestController
class LiveOrderController {
#Autowired
lateinit var redisOperations: ReactiveRedisOperations<String, LiveOrder>
#GetMapping(produces = [MediaType.TEXT_EVENT_STREAM_VALUE], value = "/orders")
fun getLiveOrders(): Flux<LiveOrder> {
val zops = redisOperations?.opsForZSet()
return zops?.rangeByScore("orders", Range.unbounded())
}
}
There is no such feature in Redis. First, reactive retrieval of a sorted set is just getting a snapshot, but your calls are going in a reactive fashion. So you need a subscription instead.
If you opt in for keyspace notifications like this (K - enable keyspace notifications, z - include zset commands) :
config set notify-keyspace-events Kz
And subscribe to them in your service like this:
ReactiveRedisMessageListenerContainer reactiveRedisMessages;
// ...
reactiveRedisMessages.receive(new PatternTopic("__keyspace#0__:orders"))
.map(m -> {
System.out.println(m);
return m;
})
<further processing>
You would see messages like this: PatternMessage{channel=__keyspace#0__:orders, pattern=__keyspace#0__:orders, message=zadd}. It will notify you that something has been added. And you can react on this somehow - get the full set again, or only some part (head/tail). You might even remember the previous set, get the new one and send the diff.
But what I would really suggest is rearchitecting the flow in some way to use Redis Pub/Sub functionality directly. For example: publisher service instead of directly calling zadd will call eval, which will issue 2 commands: zadd orders 1 x and publish orders "1:x" (any custom message you want, maybe JSON).
Then in your code you will subscribe to your custom topic like this:
return reactiveRedisMessages.receive(new PatternTopic("orders"))
.map(LiveOrder::fromNotification);
I want to add some calculated properties to an EntityObject without loosing the possibility of querying it agains the database.
I created a partial class and added the fields I need in the object. Than I wrote a static function "AttachProperties" that should somehow add some calculated values. I cannot do this on clientside, since several other functions attach some filter-conditions to the query.
The functions should look like this:
return query.Select(o =>
{
o.HasCalculatedProperties = true;
o.Value = 2;
return o;
});
In my case the calculated value depends on several lookups and is not just a simple "2". This sample works with an IEnumerable but, of course, not with an IQueryable
I first created a new class with the EntityObject as property and added the other necessary fields but now I need this extended class to be of the same basetype.
First, in my opinion changing objects in a Select() is a bad idea, because it makes something else happen (state change) than the method name suggests (projection), which is always a recipe for trouble. Linq is rooted in a functional programming (stateless) paradigm, so this kind of usage is just not expected.
But you can extend your class with methods that return a calculation result, like:
partial class EntityObject
{
public int GetValue()
{
return this.MappedProp1 * this.MappedProp2;
}
}
It is a bit hard to tell from your question whether this will work for you. If generating a calculated value involves more than a simple calculation from an object's own properties it may be better to leave your entities alone and create a services that return calculation results from an object graph.
Try something like this:
return from o in collection
select new O()
{
OtherProperty = o.OtherProperty,
HasCalculatedProperties = true,
Value = 2
};
This will create a copy of the original object with the changes you require and avoid all the messiness that come with modifying an entity in a select clause.
I want to do something like
from table1
where col5="abcd"
select col1
I did like
query_ = From g In DomainService.GetGEsQuery Select New GE With {.Desc = g.codDesc}
"This cause a runtime error, i tried various combinations but failed"
please help.
I'm assuming your trying to do this on the client side. If so you could do something like this
DomainService.Load(DomainService.GetGEsQuery().Where(g => g.codDesc == "something"), lo =>
{
if (lo.HasError == false)
{
List<string> temp = lo.Entities.Select(a => a.Name).ToList();
}
}, null);
you could also do this in the server side (which i would personally prefer) like this
public IQueryable<string> GetGEStringList(string something)
{
return this.ObjectContext.GE.Where(g => g.codDesc == something).Select(a => a.Name);
}
Hope this helps
DomainService.GetGEsQuery() returns an IQueryable, that is only useful in a subsequent asynchronous load. Your are missing the () on the method call, but that is only the first problem.
You can apply filter operations to the query returned using Where etc, but it still needs to be passed to the Load method of your domain context (called DomainService in your example).
The example Jack7 has posted shows an anonymous callback from the load method which then accesses the results inside the load object lo and extracts just the required field with another query. Note that you can filter the query in RIA services, but not change the basic return type (i.e. you cannot filter out unwanted columns on the client-side).
Jack7's second suggestion to implement a specific method server-side, returning just the data you want, is your best option.
Now I know i can only dowload a string asynchronously in Windows Phone Seven, but in my app i want to know which request has completed.
Here is the scenario:
I make a certain download request using WebClient()
i use the following code for download completed
WebClient stringGrab = new WebClient();
stringGrab.DownloadStringCompleted += ClientDownloadStringCompleted;
stringGrab.DownloadStringAsync(new Uri(<some http string>, UriKind.Absolute));
i give the user the option of giving another download request if this request takes long for the user's liking.
my problem is when/if the two requests return, i have no method/way of knowing which is which i.e. which was the former request and which was second!
is there a method of knowing/sychronizing the requests?
I can't change the requests to return to different DownloadStringCompleted methods!
Thanks in Advance!
Why not do something like this:
void DownloadAsync(string url, int sequence)
{
var stringGrab = new WebClient();
stringGrab.DownloadStringCompleted += (s, e) => HandleDownloadCompleted(e, sequence);
stringGrab.DownloadStringAsync(new Uri(url, UriKind.Absolute));
}
void HandleDownloadCompleted(DownloadStringCompletedEventArgs e, int sequence)
{
// The sequence param tells you which request was completed
}
It is an interesting question because by default WebClient doesn't carry any unique identifiers. However, you are able to get the hash code, that will be unique for each given instance.
So, for example:
WebClient client = new WebClient();
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
client.DownloadStringAsync(new Uri("http://www.microsoft.com", UriKind.Absolute));
WebClient client2 = new WebClient();
client2.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
client2.DownloadStringAsync(new Uri("http://www.microsoft.com", UriKind.Absolute));
Each instance will have its own hash code - you can store it before actually invoking the DownloadStringAsync method. Then you will add this:
int FirstHash = client.GetHashCode();
int SecondHash = client2.GetHashCode();
Inside the completion event handler you can have this:
if (sender.GetHashCode() = FirstHash)
{
// First completed
}
else
{
// Second completed
}
REMEMBER: A new hash code is given for every re-instantiation.
If the requests are essentially the same, rather than keep track of which request is being returned. Why not just keep track of if one has previously been returned? Or, how long since the last one returned.
If you're only interested in getting this data once, but are trying to allow the user to reissue the request if it takes a long time, you can just ignore all but the first successfully returned result. This way it doesn't matter how many times the user makes additional requests and you don't need to track anything unique to each request.
Similarly, if the user can request/update data from the remote service at any point, you could keep track of how long since you last got successfull data back and not bother updating the model/UI if you get another resoponse shortly after that. It'd be preferable to not make requests in this scenario but if you've got to deal with long delays and race conditions in responses you could use this technique and still keep the UI/data up to date within a threshold of a few minutes (or however long you specify).