I have the following class method :
async order(id,{ttlInSeconds}={}){
const cachedOrder=await this.cache.get(this.cacheKey(id))
if (cachedOrder){
return JSON.parse(cachedOrder)
}
const order=await this.models.Order.findOne({
where:{
id:id
}
})
if(ttlInSeconds){
await this.cache.set(this.cacheKey(id),JSON.stringify(order),{ttl:ttlInSeconds})
}
return order
}
But it never gets resolved , what am I doing wrong?
I have encountered this problem when extending Apollo's DataSource class too. I have no idea why , but you should not await for the cache to set the value, even tough in the spec it does await for the value (https://github.com/apollographql/apollo-server/blob/0aa0e4b20ef97576ce92733698a7842b61d8280e/packages/apollo-server-caching/src/KeyValueCache.ts#L10-L14). As a result , try this :
async order(id,{ttlInSeconds}={}){
const cachedOrder=await this.cache.get(this.cacheKey(id))
if (cachedOrder){
return JSON.parse(cachedOrder)
}
const order=await this.models.Order.findOne({
where:{
id:id
}
})
if(ttlInSeconds){
this.cache.set(this.cacheKey(id),JSON.stringify(order),{ttl:ttlInSeconds})
}
return order
}
Related
The Nestjs module system is great, but I'm struggling to figure out how to take full advantage of it in a Serverless setting.
I like the approach of writing my domain logic in *.service.ts files, while using *.controller.ts files to take care of non-business related tasks such as validating an HTTP request body and converting to a DTO before invoking methods in a service.
I found the section on Serverless in the nestjs docs and determined that for my specific use-case, I need to use the "standalone application feature".
I created a sample nestjs app here to illustrate my problem.
The sample app has a simple add() function to add two numbers. I use class-validator for validation on the AddDto class.
// add.dto.ts
import { IsNumber } from 'class-validator'
export class AddDto {
#IsNumber()
public a: number;
#IsNumber()
public b: number;
}
And then, via some Nestjs magic, I am able to get built-in validation using the AddDto inside my controller by doing the following:
// main.ts
async function bootstrap() {
const app = await NestFactory.create(AppModule);
// Use `ValidationPipe()` for auto-validation in controllers
app.useGlobalPipes(
new ValidationPipe({ transform: true })
)
await app.listen(3000);
}
// app.controller.ts
#Controller()
export class AppController {
constructor(private readonly appService: AppService) {}
#Post('add')
add(#Body() dto: AddDto): number {
// Request body gets auto validated and converted
// to an instance of `AddDto`, sweet!
return this.appService.add(dto.a, dto.b);
}
}
// app.service.ts
#Injectable()
export class AppService {
add(a: number, b: number): number {
return a + b
}
}
So far, so good. The problem now arises when using this in AWS with a Lambda function, namely:
I want to re-use the business logic in app.service.ts
I want to re-use built in validation that happens when making an HTTP request to the app, such as in the example above.
I want to use the standalone app feature so I don't have to spin up an entire nest server in Lambda
The docs hint on this being a problem:
Be aware that NestFactory.createApplicationContext does not wrap controller methods with enhancers (guard, interceptors, etc.). For this, you must use the NestFactory.create method.
For example, I have a lambda that receives messages from AWS EventBridge. Here's a snippet from the sample app:
// standalone-app.ts
interface IAddCommand {
a: number;
b: number;
}
export const handler = async (
event: EventBridgeEvent<'AddCommand', IAddCommand>,
context: any
) => {
const appContext = await NestFactory.createApplicationContext(AppModule);
const appService = appContext.get(AppService);
const { a, b } = event.detail;
const sum = appService.add(a, b)
// do work on `sum`, like cache the result, etc...
return sum
};
// lambda-handler.js
const { handler } = require('./dist/standalone-app')
handler({
detail: {
a: "1", // is a string, should be a number
b: "2" // is a string, should be a number
}
})
.then(console.log) // <--- prints out "12" ("1" + "2") instead of "3" (1 + 2)
I don't get "free" validation of the event's payload in event.detail like I do with #Body() dto: AddDto when making a HTTP POST request to /add. Preferentially, the code would throw a validation error in the above example. Instead, I get an answer of "12" -- a false positive.
Hopefully, this illustrates the crux of my problem. I still want to validate the payload of the event before calling appService.add(a, b), but I don't want to write custom validation logic that already exists on the controller in app.controller.ts.
Ideas? Anyone else run into this before?
It occurred to me while writing this behemoth of a question that I can simply use class-validator and class-transformer in my Lambda handler.
import { validateOrReject } from 'class-validator'
import { plainToClass } from 'class-transformer'
import { AddDto } from 'src/dto/add.dto'
export const handler = async (event: any, context: any) => {
const appContext = await NestFactory.createApplicationContext(AppModule);
const appService = appContext.get(AppService);
const data = getPayloadFromEvent(event)
// Convert raw data to a DTO
const dto: AddDto = plainToClass(AddDto, data)
// Validate it!
await validateOrReject(dto)
const sum = appService.add(dto.a, dto.b)
// do work on `sum`...
}
It's not as "free" as using app.useGlobalPipes(new ValidationPipe()), but only involves a few extra lines of code.
It worked for me with the following lambda file for nestjs.
import { configure as serverlessExpress } from '#vendia/serverless-express';
import { NestFactory } from '#nestjs/core';
import { AppModule } from './app.module';
import { ValidationPipe } from '#nestjs/common';
let cachedServer;
export const handler = async (event, context) => {
if (!cachedServer) {
const nestApp = await NestFactory.create(AppModule);
await nestApp.useGlobalPipes(new ValidationPipe());
await nestApp.init();
cachedServer = serverlessExpress({
app: nestApp.getHttpAdapter().getInstance(),
});
}
return cachedServer(event, context);
};
So I have this function in Koa, that basically checks if a user can access a specific route.
exports.requireRole = async role =>
async (ctx, next) => {
const { user } = ctx.state.user;
try {
const foundUser = await User.findById(user.id);
// If the user couldn't be found, return an error
if (!foundUser) {
ctx.status = 404;
ctx.body = { errors: [{ error: ERRORS.USER_NOT_FOUND }] };
} else {
// Otherwise, continue checking role
if (getRole(user.role) >= getRole(role)) {
await next();
}
ctx.status = 403;
ctx.body = { errors: [{ error: ERRORS.NO_PERMISSION }] };
}
} catch (err) {
ctx.throw(500, err);
}
};
And I want to use it as a middleware:
router.delete('/:id', combine([jwtAuth, requireRole(ROLES.ADMIN)]), deleteUser);
But then I get an error saying:
middleware must be a function not object
This happens only when I try to pass an argument into it.
What am I doing wrong here?
The issue you are having is due to the fact that Promises are objects, and async functions return Promises. You need to change your initial function to be as follows:
exports.requireRole = role =>
instead of
exports.requireRole = async role =>
I was going over middleware myself, and ran into this issue as well.
Your middleware looks fine, what is combine?
Also, since you are using koa-router you don't need it.
router.delete('/:id', jwtAuth, requireRole(ROLES.ADMIN), deleteUser);
I have a BaseDataService class and it has a method for HttpGet requests.
protected Get<TResponse>(
endPoint: string
): Observable<BaseResponse<TResponse>> {
return this.httpClient.get<TResponse>(this.baseUrl + endPoint).pipe(
map(data => {
const response = <BaseResponse<TResponse>>{};
response.Data = data;
response.Errors = [];
response.HasError = false;
return response;
}),
catchError(errors => {
const response = <BaseResponse<TResponse>>{};
response.Errors = [];
response.Errors.push(errors.error);
response.HasError = true;
return of(response);
})
);
}
And I have a LocationDeviceDataService which extends BaseDataService and it has a method for Get LocationDevices
getAll() {
return this.Get<BasePaginatedResponse<LocationDeviceResponse>>(
EndPoints.GET_LOCATIONDEVICES
);
}
And I am calling this method inside event ,
this.events.subscribe("connection-type:wifi", () => {
this.locationDataService.getAll().subscribe(t => {
localStorage.setItem('LOCATION_DEVICES', JSON.stringify(t.Data.items))
});
});
Everything is fine at first call , but when another events (https://ionicframework.com/docs/api/util/Events/)publish for "connection-type:wifi" this.locationDataService.getAll().subscribe returns responses 1x,2x,4x etc. slower.
I am sure for nothing wrong in back-end.
Should unsubscribe or complete subscription ? If I should , I dont have any trigger for that.
Could you please tell me what is wrong in this code ?
I solved my issue.
I think you can not call observable method inside Ionic events so I changed my method to void. Everything is fine for now.
I am making a request using observable. and trying to subcribe the value. But getting error on typescript. any on help me?
I like to do this:
public getCountry(lat,lan):Observable<any>{
return this.http.get(this.googleApi+lat+','+lan+'&sensor=false').subscribe(data => {
return this.genertedData(data);
} );
}
But getting error as follows:
UPDATES
public getCountry(lat,lan):Observable<any>{
return this.http.get(this.googleApi+lat+','+lan+'&sensor=false').map( data => {
data.results.map( array => {
let details = array.address_components.find( obj => obj.types.includes("country") );
this.countryDetails.countryLongName = details.long_name;
this.countryDetails.countryShortName = details.short_name;
})
return this.countryDetails;
})
}
The problem is that your return type states Observable<any>, where as you actually return whatever this.genertedData(data) returns (Hint: Sounds like a typo in your function. Guess it should be called generatedData ?).
Best practice would be to move the http call into a service and subscribe to its returned Observable within your component.
So to speak:
// => service.ts
public getCountryObservable(lat,lan):Observable<any> {
return this.http.get(this.googleApi+lat+','+lan+'&sensor=false');
}
Your component would look something like:
// => component.ts
export class YourComponent {
constructor(public yourService: YourService) {}
getCountry(lat, lan): whateverDataTypeYourGeneratedDataReturns {
this.yourService.getCountryObservable(lat, lan).subscribe((data) => {
this.data = this.generatedData(data);
});
}
}
Since the return type of the function is Observable<any>, I guess it should just return this.http.get(this.googleApi+lat+','+lan+'&sensor=false')
What's the recommended way to do this?
1.
factory.updater = function(varObjToBeUpdated){
$http.post('/url', {})
.success(function(data){
for (data_field in data)
varObjToBeUpdated[data_field] = data[data_field];
});
}
...
myFactory.updater($scope.varObjToBeUpdated);
Or 2.,
myFactory.updater().success(function(data, ..){
$scope.varObjToBeUpdated = data;
});
...
factory.updater = function(){
return $http.post('/url', {});
}
Is it ok to to pass a reference scope variable to a factory? I always thought factories as delivering data.
And what's wrong with the second method (if it's less acceptable)?
I prefer the second approach, as this allows you to just inject the service when you need it across multiple controllers. Use .then to continue the promise pattern:
myFactory.updater().then(function(data, ..){
$scope.varObjToBeUpdated = data;
});
app.factory('myFactor', function($http) {
return {
updater: function() {
return $http({'/url',}).then(function(result) {
return result.data;
});
}
}
});