Spring webflux : webClient put call - rest

Question

I have an account service and a product service communicating. When a request comes from a user to purchase a product (I did not include the user service, it is working fine and not the issue), the product service checks to see if there are enough funds in the account, and if there is it updates the balances. The following code works fine:
#GetMapping("/account/{userId}/product/{productId}")
public Mono<ResponseEntity<Product>> checkAccount(#PathVariable("userId") int userId,#PathVariable("productId") int productId){
Mono<Account> account = webClientBuilder.build().get().uri("http://account-service/user/accounts/{userId}/",userId)
.retrieve().bodyToMono(Account.class);
Mono<Product> product = this.ps.findById(productId);
Mono<Boolean> result = account.zipWith(product,this::isAccountBalanceGreater);
Mono<ResponseEntity<Product>> p = result.zipWith(product,this::getResponse);
return p;
}
public boolean isAccountBalanceGreater(Account acc, Product prd) {
return(acc.getBalance()>=prd.getPrice()):
}
public ResponseEntity<Product> getResponse(boolean result,Product prod){
if(result) {
return ResponseEntity.accepted().body(prod);
}else {
return ResponseEntity.badRequest().body(prod);
}
}
My put method in the account service also works fine:
#PutMapping("/account/update/{accountId}")
public Mono<ResponseEntity<Account>> updateAccount(#PathVariable("accountId") int accountId, #RequestBody Account account) {
return as.findById(accountId)
.flatMap(oldAcc->{
oldAcc.setAccountId(account.getAccountId());
oldAcc.setAccountId(account.getAccountId());
oldAcc.setOwner(account.getOwner());
oldAcc.setPin(account.getPin());
oldAcc.setBalance(account.getBalance());
oldAcc.setUserId(account.getUserId());
return ar.save(oldAcc);
}).map(a -> ResponseEntity.ok(a))
.defaultIfEmpty(ResponseEntity.notFound().build());
}
Now I want to be able to update the balances, I have tried this in the isAccountBalancerGreater method:
public boolean isAccountBalanceGreater(Account acc, Product prd) {
if(acc.getBalance() >= prd.getPrice()) {
double newBuyerBalance =acc.getBalance() - prd.getPrice();
Account newOwnerAcc = new Account(acc.getAccountId(),acc.getOwner(),acc.getPin(),newBuyerBalance,acc.getUserId());
this.ps.removeProduct(prd.getProductId());
webClientBuilder.build().put().uri("http://account-service/account/update/{accountId}",acc.getAccountId()).body(newOwnerAcc,Account.class).exchange();
return true;
}
return false;
}
However this does not work, not error just nothing updates.
My test case works when I run the same code with a test account. I'm not sure why this is not executing. Any suggestions?

Answer 1

you have to think of reactive code as event chains or callbacks. So you need to respond to what you want something to do, after some other thing has been completed.
return webClientBuilder.build()
.put().uri("http://account-service/account/update/{accountId}",
acc.getAccountId())
.body(newOwnerAcc,Account.class)
.exchange()
.thenReturn(true); // if you really need to return a boolean
return a boolean is usually not semantically correct in a reactive world. Its very common to try to avoid if-else statements
One way is to return a Mono<Void> to mark that something has been completed, and trigger something chained onto it.
public Mono<Void> isAccountBalanceGreater(Account acc, Product prd) {
return webclient.put()
.uri( ... )
.retrieve()
.bodyToMono(Void.class)
.doOnError( // handle error )
}
// How to call for example
isAccountBalanceGreater(foo, bar)
.doOnSuccess( ... )
.doOnError( ... )