How do I create a service that does only one processing, without registering in the database. An example: sending any data it does a processing using a hook and returns the result.
Here it works more the return is the answer of the data in the database, I do not care to store
app.use('/process', createService(options));
I tried something like this but got an error. Sorry, I am new to it.
app.use('/process', function(req, res) {
});
This is explained in detail in the Basics guide of the FeathersJS documentation, specifically the services section. The API documentation can be found here. A service is any object or class that implements one or more of the following methods which can do pretty much anything:
class MyService {
async find(params) {
return [];
}
async get(id, params) {}
async create(data, params) {}
async update(id, data, params) {}
async patch(id, data, params) {}
async remove(id, params) {}
setup(app, path) {}
}
app.use('/my-service', new MyService());
A custom service can be generated with the CLI via feathers generate service and choosing the "A custom service" option. It can then be edited in src/services/<name>/<name>.class.js.
Related
So, before I go deep in the problem let me explain you the basic of my app.
I have connection to DB(TypeOrm), Kafka(kafkajs) in my app.
My app is the Consumer of 1 topic which:
Gets some data in the callback handler, and puts that data in one table using TypeORM Entity
Maintains the Global map (in some Singleton Instance of a class) with some id (that I get in data of point 1).
At the time of app getting shutdown, my task is:
Disconnect all the consumers of the topics (this service is connected to) from the Kafka
Traverse the Global Map (point 2) and repark the message in the some topic
Disconnect the DB connections using the close method.
Here are some piece of code that might help you understand how I added the life cycle events on Server in NestJs.
system.server.life.cycle.events.ts
#Injectable()
export class SystemServerLifeCycleEventsShared implements BeforeApplicationShutdown {
constructor(#Inject(WINSTON_MODULE_PROVIDER) private readonly logger: Logger, private readonly someService: SomeService) {}
async beforeApplicationShutdown(signal: string) {
const [err] = await this.someService.handleAbruptEnding();
if (err) this.logger.info(`beforeApplicationShutdown, error::: ${JSON.stringify(err)}`);
this.logger.info(`beforeApplicationShutdown, signal ${signal}`);
}
}
some.service.ts
export class SomeService {
constructor(private readonly kafkaConnector: KafkaConnector, private readonly postgresConnector: PostgresConnector) {}
public async handleAbruptEnding(): Promise<any> {
await this.kafkaConnector.disconnectAllConsumers();
for(READ_FROM_GLOBAL_STORE) {
await this.kafkaConnector.function.call.to.repark.the.message();
}
await this.postgresConnector.disconnectAllConnections();
return true;
}
}
postgres.connector.ts
export class PostgresConnector {
private connectionManager: ConnectionManager;
constructor () {
this.connectionManager = getConnectionManager();
}
public async disconnectAllConnections(): Promise<void[]> {
const connectionClosePromises: Promise<void> = [];
connectionManager.connections?.forEach((connection) => {
if (connection.isConnected) connectionClosePromises.push(connection.close());
});
return Promise.all(connectionClosePromises);
}
}
ConnectionManager& getConnectionManager() imported from TypeORM module.
Now here are some unusual exceptions / behavior I am facing:
Disconnect all connections is throwing exception/error as in quote:
ERROR [TypeOrmModule] Cannot execute operation on "default" connection because connection is not yet established.
If connection is not yet established then how come my isConnected came true inside of if. I am not getting any clue anywhere how is this possible. And how to do graceful shutdown of the connection in TypeORM.
Do we really need to handle the closure of the connection in TypeORM or it internally handles it.
Even if, TypeORM handles the connection closure internally, how could we achieve it explicitly.
Is there any callback that can be triggered in case the connection is disconnected properly so that I am sure, that disconnection actually happened from the db.
Some of the messages are coming after I press CTRL + C (mimicking the abrupt/closure of the process of my server) and the control comes back to Terminal. This means, some thread is coming back after the handle returns to my terminal (🤷, no clue, how would I handle this, since if you see, my handleAbruptHandling is awaited and also, I cross checked all the promises are being awaited properly.)
Some of the things to know:
I properly added my module to create the hooks of server life cycle events.
Injected the objects in almost all the classes properly.
Not getting any DI issue from NEST and server is getting started properly.
Please shed some light and let me know how can I gracefully disconnect from db using typeorm api inside NestJs in case of abrupt closure.
Thanks in advance and happy coding :)
Littlebit late but may help someone..
You are missing the param keepConnectionAlive as true in TypeOrmModuleOptions, typeOrm dont keep connections alive as default. I set keepConnectionAlive as false, if a transaction keeps the connection open im going to close the connection (typeorm wait until the transaction or other process finish before close the connection), this is my implementation
import { Logger, Injectable, OnApplicationShutdown } from '#nestjs/common';
import { getConnectionManager } from 'typeorm';
#Injectable()
export class LifecyclesService implements OnApplicationShutdown {
private readonly logger = new Logger();
onApplicationShutdown(signal: string) {
this.logger.warn('SIGNTERM: ', signal);
this.closeDBConnection();
}
closeDBConnection() {
const conn = getConnectionManager().get();
if (conn.isConnected) {
conn
.close()
.then(() => {
this.logger.log('DB conn closed');
})
.catch((err: any) => {
this.logger.error('Error clossing conn to DB, ', err);
});
} else {
this.logger.log('DB conn already closed.');
}
}
}
I discovered some TypeORM docs saying "Disconnection (closing all connections in the pool) is made when close is called"
Here: https://typeorm.biunav.com/en/connection.html#what-is-connection
I tried export const AppDataSource = new DataSource({ // details }) and importing it and doing
import { AppDataSource } from "../../src/db/data-source";
function closeConnection() {
console.log("Closing connection to db");
// AppDataSource.close(); // said "deprecated - use destroy() instead"
AppDataSource.destroy(); // hence I did this
}
export default closeConnection;
Maybe this will save someone some time
I am looking for existing solutions to match dynamic parameters with HttpCore. What I have in mind is something similar to constraints in ruby on rails, or dynamic parameters with sails (see here for example).
My objective is to define a REST API where I could easily match requests like GET /objects/<object_id>.
To give a little bit of context, I have an application that creates an HttpServer using the following code
server = ServerBootstrap.bootstrap()
.setListenerPort(port)
.setServerInfo("MyAppServer/1.1")
.setSocketConfig(socketConfig)
.registerHandler("*", new HttpHandler(this))
.create();
And the HttpHandler class that matches the requested URI and dispatches it to the corresponding backend method:
public void handle(final HttpRequest request, final HttpResponse response, final HttpContext context) {
String method = request.getRequestLine().getMethod().toUpperCase(Locale.ROOT);
// Parameters are ignored for the example
String path = request.getRequestLine().getUri();
if(method.equals("POST") && path.equals("/object/add") {
if(request instanceof HttpEntityEnclosingRequest) {
addObject(((HttpEntityEnclosingRequest)request).getEntity())
}
[...]
For sure I can replace path.equals("/object/add") by something more sophisticated with RegEx to match these dynamic parameters, but before doing so I'd like to know if I am not reinventing the wheel, or if there is an existing lib/class I didn't see in the docs that could help me.
Using HttpCore is a requirement (it is already integrated in the application I am working on), I know some other libraries provide high-level routing mechanisms that support these dynamic parameters, but I can't really afford switching the entire server code to another library.
I am currently using httpcore 4.4.10, but I can upgrade to a newer version of this might help me.
At present HttpCore does not have a fully featured request routing layer. (The reasons for that are more political than technical).
Consider using a custom HttpRequestHandlerMapper to implement your application specific request routing logic.
final HttpServer server = ServerBootstrap.bootstrap()
.setListenerPort(port)
.setServerInfo("Test/1.1")
.setSocketConfig(socketConfig)
.setSslContext(sslContext)
.setHandlerMapper(new HttpRequestHandlerMapper() {
#Override
public HttpRequestHandler lookup(HttpRequest request) {
try {
URI uri = new URI(request.getRequestLine().getUri());
String path = uri.getPath();
// do request routing based on the request path
return new HttpFileHandler(docRoot);
} catch (URISyntaxException e) {
// Provide a more reasonable error handler here
return null;
}
}
})
.setExceptionLogger(new StdErrorExceptionLogger())
.create();
I have a simple program that consumes IMDB api, I'm getting the result, but it was shown as error because the result is not a structured json.
MovieService.ts
export class MovieService {
constructor(private http:HttpClient) { }
getMovie(movie:string){
return this.http.get(this.generateURL(movie));
}
private generateURL(movie:string){
return "https://v2.sg.media-imdb.com/suggests/titles/"+movie.charAt(0)+"/"+movie+".json?callback=imdb$"+movie;
}
}
addmovie.component.ts
private _filterMovies(value: string) {
this.movieService.getMovie(value).subscribe(
movies => {
console.log(movies);
return movies;
}
);
}
ngOnInit() {
this.addMovieForm.get('movie').valueChanges.subscribe(val => {
this._filterMovies(val)
});
}
I'm getting error like
the response is of bad json. How can I format the json upon receiving? How to solve this? Any leads would be helpful.
The result is not JSON, but rather JSONP. It is essentially returning you a script that is trying to execute the callback method specified.
Instead of http.get() you should call http.jsonp(url, "imbdIgnoresThisParam").
However, according to this answer, the callback query string parameter is ignored by IMDB. The answer suggests dynamically creating the expected callback function, whose name contains the title for which you are searching. In that callback you could do a few different things.
Use the closure to call / set something in your MovieService. This will result in your call to the API throwing an error, as the Angular framework's callback will not be called as expect. You could ignore the error.
Try to call the expected Angular callback, ng_jsonp_callback_<idx>. This will prevent the API call from throwing, but it may not be reliable. The callback name is dynamic and increments with each jsonp() call. You could try to track the number of jsonp() calls in your app. And of course, the framework may change and break this solution. Concurrent calls to getMovie() may break, as the next one may step on the previous callback on the window. Use with caution!
In typescript, your getMovie() function and related helpers might look like so:
private imdbData: any = null;
private jsonpIdx = 0;
private setImdb(json: any) {
this.imdbData = json;
// or do whatever you need with this
}
getMovie(movie:string) {
// dynamically create the callback on the window.
let funcName = `imdb$${movie}`;
window[funcName] = (json: any) => {
// use the closure
this.setImdbData(json);
// or try to call the callback that Angular is expecting.
window[`ng_jsonp_callback_${this.jsonpIdx++}`](json);
}
// go get your data!
let url = this.generateURL(movie)
return this.http.jsonp(url, "ignored").subscribe((json) => {
// this happens if you successfully trigger the angular callback
console.log(json);
}, (err) => {
// this happens if the angular callback isn't called
console.log(this.imdbData); // set in closure!
});
}
Edit for Angular 4
For Angular 4, it looks like you will need to import the JsonpModule along with the HttpModule. Then, you'd inject jsonp just like you'd inject http into your service. The call to IMDB becomes this.jsop.request(url).subscribe(...) and your dynamic callback name needs to change, too.
window[funcName] = (json: any) => {
// or try to call the callback that Angular is expecting.
window["__ng_jsonp__"][`__req${this.jsonpIdx++}`]["finished"](json);
}
I don't have an Angular 5 or 6 project immediately set up, so hard to say if there are any differences with the callback in those versions.
Sort of a hack, but hope it helps!
I am using the following code to generate a JSON for a Salesforce custom object called Resource Booking. How can I "run" the file (or call responseJSON) so that when I input the custom URL (in the first comment) it jumps to a page similar to this example web page? https://www.googleapis.com/customsearch/v1?json
Here is my code:
#RestResource(urlMapping='/demo/createTask/*') //endpoint definition > {Salesforce Base URL}/services/apexrest/demo/createTask/
global class ResourceBookingTransfer {
public List<Resource_Booking__c> resourceBookingList{get; set;}
public ResourceBookingTransfer(ApexPages.StandardController controller) {
//getResourceBookingList();
}
#HttpGet //HttpGet request
global static responseWrapper getResourceBookingList() {
responseWrapper responseJSON = new responseWrapper(); //responseWrapper object for API response
responseJSON.message = 'Hello World';
return responseJSON; //return the JSON response
//resourceBookingList = Database.query('SELECT Booking_ID__c, Booking_Name__c, Start_Date_Time__c, End_Date_Time__c, Resource__c FROM Resource_Booking__c');
}
//wrapper class for the response to an API request
global class responseWrapper {
global String message {get;set;} //message string
//constructor
global responseWrapper() {
this.message = '';
}
}
}
To just test it - it might be simplest to use https://workbench.developerforce.com. There's "REST explorer" menu in there. Your code should be available under resource similar to /services/apexrest/demo/createTask.
Why that url? Read https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_rest_code_sample_basic.htm
Once you're happy with this manual testing - you can try to do it from outside workbench. Workbench logs you in to SF and passed header with valid session id in the background. If you want to call your service from another website or mobile app - you need to perform login call first, get the session id and then run your code. There are several OAuth flows you can use to do this depending in what your app needs, maybe start with this one: https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/intro_understanding_username_password_oauth_flow.htm
I'm beggining to play with Angular2. I have developed a basic RESTful API using Jersey. I tested it and it works fine (with browser and SOAP UI). This is the code:
#GET
#Produces(MediaType.APPLICATION_JSON)
public TwoWordsMessage getMessage() {
TwoWordsMessage message = new TwoWordsMessage();
message.setFirstWord("hello");
message.setSecondWord("world");
return message;
}
I'm tryng to call the service from an Angular2 app:
this.http.request(this.url).subscribe((res: Response) => {
this.message = res.json();
});
I can see (debbuging) that "getMessage" method is called and it returns the TwoWordsMessage object but the Angular2 application never gets it. The same code with the url http://jsonplaceholder.typicode.com/posts/1 works fine.
What I'm doing wrong?
Thanks!
Are you calling the http request inside a component or a service? Does a function or method fire off the http request?
Also, can you see if there are errors coming back from the response? The subscribe method can take three functions as parameters, first one being on success, second on error, third on completion. If there's an error in the AJAX call (400s, 500s, etc), your code would never be able to handle it. Try this:
this.http.request(this.url).subscribe((res: Response) => {
this.message = res.json();
}, (error) => {
console.warn(error)
});
and see what is spit out. To further debug, you can even use the .do() method on the Observable:
this.http.request(this.url)
.do((res: Response) => console.log(res)) // or other stuff
.subscribe((res: Response) => {
this.message = res.json();
});
The .do() method will execute an arbitrary function with the response without actually affecting it.
If not, you could also try changing the http call to http.get(). I don't think that's the problem, but the Angular docs do not state what method is defaulted to with http.request() (although I would be almost certain it's a GET).
I finally got it working. It's a CORS problem.
The console showed the error:
"No 'Access-Control-Allow-Origin' header is present on the requested
resource"
I changed the resource method like this:
#GET
#Produces(MediaType.APPLICATION_JSON)
public Response getMessage() {
TwoWordsMessage message = new TwoWordsMessage();
message.setFirstWord("hello");
message.setSecondWord("world");
return Response.status(200).header("Access-Control-Allow-Origin", "*").entity(message).build();
}
You can find useful information here:
http://www.codingpedia.org/ama/how-to-add-cors-support-on-the-server-side-in-java-with-jersey/