The tutorial demonstrates how to implement an idempotency decorator in NestJS to protect POST routes from duplicate requests. It covers creating the decorator, integrating the interceptor, configuring Axios, and testing the implementation with Postman to ensure consistent system state through keyed requests.
Length 13:59
Captions English (Generated), Spanish (Auto-translated), French (Auto-translated), Korean (Auto-translated), Portuguese (Auto-translated), Vietnamese (Auto-translated) #nestjs #idempotency #decorator #interceptor #controller #typescript #backend #api #postman #programming
0:00 All right, so in this lecture, we're finally ready to test out our new 0:03 idempotency 0:04 implementation. 0:05 In order to do this, let's go ahead and head back into our source directory 0:09 and we have our demo controller. And inside of the upstream 0:13 controller, we're now gonna create a new endpoint to 0:17 use our idempotent interceptor. Now, in order to 0:21 actually use the idempotency interceptor, we're gonna take advantage 0:25 of NestJS decorators, and in this case, a special 0:29 decorator that they provide us that allows us to directly 0:32 invoke an interceptor before a given route. 0:35 And so let's go ahead and see how we can use this inside of 0:38 NestJS. 0:39 For this, I'm gonna create the new 0:41 idempotent.decorator.ts and make 0:45 sure we've created this inside of our HTTP directory as well. 0:49 And now inside of here, I'm gonna create a new decorator that we 0:53 will capitalize and call idempotent. 0:55 This is going to be a callback function where we now go ahead 0:59 and return applyDecorators from NestJS common, 1:03 which allows us to apply any decorator to a given route. 1:07 In this case, we can use the 1:10 useInterceptors function 1:14 from NestJS common as well 1:16 that returns a new decorator that applies all decorators provided by 1:20 param. It's essentially a way to allow us to 1:22 build new decorators or a 1:24 decorator factory encapsulating multiple decorators related with the same 1:28 feature. So all that is just short of saying this takes in the 1:32 underlying interceptor that we want to now use. 1:35 So we just have to pass in the server idempotencyInterceptor now, 1:40 which will be invoked thanks to useInterceptors, which takes in the 1:43 interceptor we want to invoke and that returns us back the 1:47 decorator that applyDecorators then expects. 1:50 And all this will then allow the idempotencyInterceptor to 1:53 execute before and after the route through the use of RxJS
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