I'm trying to figure out how to
programically instantiate a struct with set values (one of those might be yet another nested struct - or not) - and save it in Redis.
fetch it back into a struct from Redis
I am aware that the 2 traits ToRedisArgs and FromRedisValue are to be implemented here, but even for my very simple 2 structs I have no clue what to write to impl them in Rust. I've made a simple example:
extern crate redis;
use redis::Commands;
// fn fetch_an_integer() -> redis::RedisResult<isize> {
// // connect to redis
// let client = try!(redis::Client::open("redis://127.0.0.1/"));
// let con = try!(client.get_connection());
// // throw away the result, just make sure it does not fail
// let _ : () = try!(con.set("my_key", 42));
// // read back the key and return it. Because the return value
// // from the function is a result for integer this will automatically
// // convert into one.
// con.get("my_key")
// }
fn fetch_a_struct() -> redis::RedisResult<MyStruct> {
// connect to redis
let client = try!(redis::Client::open("redis://127.0.0.1/"));
let con = try!(client.get_connection());
// throw away the result, just make sure it does not fail
let another_struct = AnotherStruct{x: "another_struct".to_string()};
let mut my_vec: Vec<AnotherStruct> = Vec::new();
my_vec.push(another_struct);
let my_struct = MyStruct{x: "my_struct".to_string(), y: 1, z: my_vec};
let _ : () = try!(con.set("my_key_struct", my_struct));
con.get("my_key_struct")
}
fn main() {
match fetch_a_struct() {
Err(err) => {
println!("{}", err)
},
Ok(x) => {
println!("{}", x.x)
}
}
}
struct MyStruct {
x: String,
y: i64,
z: Vec<AnotherStruct>,
}
struct AnotherStruct {
x: String
}
(Playground)
I need to save different visitors, their browsing behavior (duration, pages visited and other interactions etc) and other stats while they browse around my website - That's why I was thinking about using Redis instead of MongoDB, as my outproc session store.
In MongoDB I'd have a user collection, interactions collection etc... but what might the equivalent way in Redis be?
Being a complete newbie at both Redis and Rust I hope you can help me at least to get a few ideas how to achieve something like this.
Serialize your data to a JSON string, save it as a string and then deserialize it when needed.
Related
I am using spring hexagonal architecture (port and adapter) as my application need to read the stream of data from the source topic, process/transforms the data, and send it to destination topic.
My application need to do the following actions.
Read the data (which will have the call back url)
Make an http call with the url in the incoming data (using webclient)
Get the a actual data and it needs to be transformed into another format.
Send the transformed data to the outgoing topic.
Here is my code,
public Flux<TargeData> getData(Flux<Message<EventInput>> message)
{
return message
.flatMap(it -> {
Event event = objectMapper.convertValue(it.getPayload(), Event.class);
String eventType = event.getHeader().getEventType();
String callBackURL = "";
if (DISTRIBUTOR.equals(eventType)) {
callBackURL = event.getHeader().getCallbackEnpoint();
WebClient client = WebClient.create();
Flux<NodeInput> nodeInputFlux = client.get()
.uri(callBackURL)
.headers(httpHeaders -> {
httpHeaders.setContentType(MediaType.APPLICATION_JSON);
List<MediaType> acceptTypes = new ArrayList<>();
acceptTypes.add(MediaType.APPLICATION_JSON);
httpHeaders.setAccept(acceptTypes);
})
.exchangeToFlux(response -> {
if (response.statusCode()
.equals(HttpStatus.OK)) {
System.out.println("Response is OK");
return response.bodyToFlux(NodeInput.class);
}
return Flux.empty();
});
nodeInputFlux.subscribe( nodeInput -> {
SourceData source = objectMapper.convertValue(nodeInput, SourceData.class);
// return Flux.fromIterable(this.TransformImpl.transform(source));
});
}
return Flux.empty();
});
}
The commented line in the above code is giving the compilation as subscribe method does not allow return types.
I need a solution "without using block" here.
Please help me here, Thanks in advance.
I think i understood the logic. What do you may want is this:
public Flux<TargeData> getData(Flux<Message<EventInput>> message) {
return message
.flatMap(it -> {
// 1. marshall and unmarshall operations are CPU expensive and could harm event loop
return Mono.fromCallable(() -> objectMapper.convertValue(it.getPayload(), Event.class))
.subscribeOn(Schedulers.parallel());
})
.filter(event -> {
// 2. Moving the if-statement yours to a filter - same behavior
String eventType = event.getHeader().getEventType();
return DISTRIBUTOR.equals(eventType);
})
// Here is the trick 1 - your request below return Flux of SourceData the we will flatten
// into a single Flux<SourceData> instead of Flux<List<SourceData>> with flatMapMany
.flatMap(event -> {
// This WebClient should not be created here. Should be a singleton injected on your class
WebClient client = WebClient.create();
return client.get()
.uri(event.getHeader().getCallbackEnpoint())
.accept(MediaType.APPLICATION_JSON)
.exchangeToFlux(response -> {
if (response.statusCode().equals(HttpStatus.OK)) {
System.out.println("Response is OK");
return response.bodyToFlux(SourceData.class);
}
return Flux.empty();
});
})
// Here is the trick 2 - supposing that transform return a Iterable of TargetData, then you should do this and will have Flux<TargetData>
// and flatten instead of Flux<List<TargetData>>
.flatMapIterable(source -> this.TransformImpl.transform(source));
}
Im new to swift development and I can't make myself pass through this. I run my app and by pressing the "action" button I see no change on my text which should be the current temperature. And It's giving me an error "nw_protocol_get_quic_image_block_invoke dlopen libquic failed"
My code:
struct ContentView: View {
#State var temp = Int()
func CallApi(){
let url = URL(string: "https://api.openweathermap.org/data/2.5/weather?q=budapest&appid=#########################################")
URLSession.shared.dataTask(with: url!){data, response, error in
if let data = data {
if let DecodedData = try? JSONDecoder().decode(Api.self, from: data){
self.temp = DecodedData.main.temp
}
}
}.resume()
}
struct Api: Codable, Hashable{
var main: DataStructre
}
struct DataStructre: Codable, Hashable {
var temp: Int
}
var body: some View {
Text("\(temp)")
Button("Idojaras"){CallApi()}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
If you use do/try/catch instead of try?, you can get a useful error message.
do {
let DecodedData = try JSONDecoder().decode(Api.self, from: data)
self.temp = DecodedData.main.temp
} catch {
print(error)
}
In this case, I get:
Parsed JSON number <304.31> does not fit in Int.
Changing the type of temp (in both the #State variable and the DataStructre) fixes the issue.
In general, I'd recommend pasting your JSON into app.quicktype.io, which will give you generated models with the correct types/structures.
Slightly unrelated to your issue, but you may want to look into using dataTaskPublisher and Combine in SwiftUI rather than dataTask (https://developer.apple.com/documentation/foundation/urlsession/processing_url_session_data_task_results_with_combine). Also, function names in Swift are generally lowercased.
I have a large amount of tests in my Rust code, and I require a RSA key pair for each of them. However, generating RSA key pairs is expensive and takes 3-4 seconds. I can reuse a single RSA key pair across all tests, but I'm not sure how to do that. At the moment, I'm generating an RSA key pair for each test separately.
Update: The tests are async tests and need to use the key pairs as Arcs, so lazy_static! won't work (returns reference)
What I have right now:
use rsa::{hash, PaddingScheme, PublicKey, RSAPublicKey};
#[cfg(test)]
mod tests {
use super::*;
#[tokio::test]
async fn test_1() {
let (pub_key, priv_key) = new_keypair();
// ...
}
#[tokio::test]
async fn test_2() {
let (pub_key, priv_key) = new_keypair();
// ...
}
// ...
fn new_keypair() -> (RSAPublicKey, RSAPrivateKey) {
use rand::rngs::OsRng;
let mut rng = OsRng;
let bits = 2048;
let private_key =
RSAPrivateKey::new(&mut rng, bits).expect("Failed to generate private key");
let public_key = RSAPublicKey::from(&private_key);
(public_key, private_key)
}
}
(pseudocode for) What I need:
use rsa::{hash, PaddingScheme, PublicKey, RSAPublicKey};
#[cfg(test)]
mod tests {
use super::*;
// Pseudo-code
#[tokio::test_main]
async fn main() {
let (pub_key, priv_key) = new_keypair();
run_tests(pub_key, priv_key);
}
#[tokio::test]
async fn test_1(pub_key: RSAPublicKey, priv_key: RSAPrivateKey) {
// ...
}
#[tokio::test]
async fn test_2(pub_key: RSAPublicKey, priv_key: RSAPrivateKey) {
// ...
}
// ...
fn new_keypair() -> (RSAPublicKey, RSAPrivateKey) {
use rand::rngs::OsRng;
let mut rng = OsRng;
let bits = 2048;
let private_key =
RSAPrivateKey::new(&mut rng, bits).expect("Failed to generate private key");
let public_key = RSAPublicKey::from(&private_key);
(public_key, private_key)
}
}
You can use lazy_static to initialize the key pair only once.
However, with this approach, you will only be able to work with shared references.
If that is not a problem for your use case, the following code should get you started.
Edited in response to update: The same principle also applies when dealing with other types. The following code uses Arc and async tests.
use rsa::RSAPrivateKey;
use std::sync::Arc;
pub async fn consume(key: Arc<RSAPrivateKey>) {
// unimplemented!("")
}
#[cfg(test)]
mod tests {
use super::*;
use lazy_static::lazy_static;
use rsa::{RSAPrivateKey, RSAPublicKey};
use std::sync::Arc;
lazy_static! {
static ref PRIV_KEY: Arc<RSAPrivateKey> = Arc::new(new_priv_key());
static ref PUB_KEY: Arc<RSAPublicKey> = Arc::new(PRIV_KEY.to_public_key());
}
#[tokio::test]
async fn test_1() {
let priv_key = PRIV_KEY.clone();
consume(priv_key).await
}
fn new_priv_key() -> RSAPrivateKey {
use rand::rngs::OsRng;
let mut rng = OsRng;
let bits = 2048;
let private_key =
RSAPrivateKey::new(&mut rng, bits).expect("Failed to generate private key");
private_key
}
}
Based on the documentation of RSAPrivateKey, you might not even need the RSAPublicKey, since RSAPrivateKey implements the PublicKey trait.
I'm trying to fetch some data with this helper file:
https://gist.github.com/jbfbell/e011c5e4c3869584723d79927b7c4b68
Here's a snippet of the important code:
Class
/// Base class for requests to the Alpha Vantage Stock Data API. Intended to be subclasssed, but can
/// be used directly if library does not support a new api.
class AlphaVantageRequest : ApiRequest {
private static let alphaApi = AlphaVantageRestApi()
let method = "GET"
let path = ""
let queryStringParameters : Array<URLQueryItem>
let api : RestApi = AlphaVantageRequest.alphaApi
var responseJSON : [String : Any]? {
didSet {
if let results = responseJSON {
print(results)
}
}
}
}
Extension ApiRequest
/// Makes asynchronous call to fetch response from server, stores response on self
///
/// - Returns: self to allow for chained method calls
public func callApi() -> ApiRequest {
guard let apiRequest = createRequest() else {
print("No Request to make")
return self
}
let session = URLSession(configuration: URLSessionConfiguration.ephemeral)
let dataTask = session.dataTask(with: apiRequest) {(data, response, error) in
guard error == nil else {
print("Error Reaching API, \(String(describing: apiRequest.url))")
return
}
self.receiveResponse(data)
}
dataTask.resume()
return self
}
My goal is to fetch the data from responseJSON after the data of the url request is loaded.
My ViewModel currently looks like this:
class CompanyViewModel: ObservableObject {
var companyOverviewRequest: ApiRequest? {
didSet {
if let response = companyOverviewRequest?.responseJSON {
print(response)
}
}
}
private var searchEndpoint: SearchEndpoint
init(companyOverviewRequest: AlphaVantageRequest? = nil,
searchEndpoint: SearchEndpoint) {
self.companyOverviewRequest = CompanyOverviewRequest(symbol: searchEndpoint.symbol)
}
func fetchCompanyOverview() {
guard let request = self.companyOverviewRequest?.callApi() else { return }
self.companyOverviewRequest = request
}
}
So in my ViewModel the didSet gets called once but not when it should store the data. The results of AlphaVantageRequest always prints out properly, but not in my ViewModel. How can I achieve to have the loaded data also in my ViewModel?
When you use a view model which is an ObservableObject, your view wants to observe published properties, usually a viewState (MVVM terminology):
class CompanyViewModel: ObservableObject {
enum ViewState {
case undefined
case value(Company)
}
#Published var viewState: ViewState = .undefined
viewState completely describes how your view will be rendered. Note, that it can be undefined - which your view should be able to handle.
Adding a loading(Company?) case would also be a good idea. Your view can then render a loading indicator. Note that loading also provides an optional company value. You can then render a "refresh", in which case you already have a company value while also drawing a loading indicator.
In order to fetch some data from an endpoint, you may use the following abstraction:
public protocol HTTPClient: class {
func publisher(for request: URLRequest) -> AnyPublisher<HTTPResponse, Swift.Error>
}
This can be implemented by a simple wrapper around URLSession with 5 lines of code. A conforming type may however do much more: it may handle authentication, authorization, it may retry requests, refresh access tokens, or present user interfaces where the user needs to authenticate, etc. This simple protocol is sufficient for all this.
So, how does your ViewModel get the data?
It makes sense to introduce another abstraction: "UseCase" which performs this task, and not let the view model directly use the HTTP client.
A "use case" is simply an object that performs a task, taking an input and producing an output or error. You can name it how you want, "DataProvider", "ContentProvider" or something like this. "Use Case" is a well known term, though.
Conceptually, it has a similar API as an HTTP client, but semantically it sits on a higher level:
public protocol UseCase {
associatedtype Input: Encodable
associatedtype Output: Decodable
associatedtype Error
func callAsFunction(with input: Input) -> AnyPublisher<Output, Error>
}
Lets create us a "GetCompany" use case:
struct Company: Codable {
var name: String
var id: Int
}
struct GetCompanyUseCase: UseCase {
typealias Input = Int
typealias Output = Company
typealias Error = Swift.Error
private let httpClient: HTTPClient
init(httpClient: HTTPClient) {
self.httpClient = httpClient
}
func callAsFunction(with id: Int) -> AnyPublisher<Company, Swift.Error> {
let request = composeURLRequest(input: id)
return httpClient.publisher(for: request)
.tryMap { httpResponse in
switch httpResponse {
case .success(_, let data):
return data
default:
throw "invalid status code"
}
}
.decode(type: Company.self, decoder: JSONDecoder())
.map { $0 } // no-op, usually you receive a "DTO.Company" value and transform it into your Company type.
.eraseToAnyPublisher()
}
private func composeURLRequest(input: Int) -> URLRequest {
let url = URL(string: "https://api.my.com/companies?id=\(input)")!
return URLRequest(url: url)
}
}
So, this Use Case clearly accesses our HTTP client. We can implement this accessing CoreData, or read from file, or using a mock, etc. The API is always the same, and the view model does not care. The beauty here is, you can switch it out and swap in another one, the view model still works and also your view. (In order to make this really cool, you would create a AnyUseCase generic type, which is very easy, and here you have your dependency injection).
Now lets see how the view model may look like and how it uses the Use Case:
class CompanyViewModel: ObservableObject {
enum ViewState {
case undefined
case value(Company)
}
#Published var viewState: ViewState = .undefined
let getCompany: GetCompanyUseCase
var getCompanyCancellable: AnyCancellable?
init(getCompany: GetCompanyUseCase) {
self.getCompany = getCompany
}
func load() {
self.getCompanyCancellable =
self.getCompany(with: 1)
.sink { (completion) in
print(completion)
} receiveValue: { (company) in
self.viewState = .value(company)
print("company set to: \(company)")
}
}
}
The load function triggers the use case, which calls the underlying http client to load the company data.
When the UseCase returns a company, it will be assigned the view state. Observers (the view, or ViewController) will get notified about the change and can preform an update.
You can experiment with code in playground. Here are the missing peaces:
import Foundation
import Combine
extension String: Swift.Error {}
public enum HTTPResponse {
case information(response: HTTPURLResponse, data: Data)
case success(response: HTTPURLResponse, data: Data)
case redirect(response: HTTPURLResponse, data: Data)
case clientError(response: HTTPURLResponse, data: Data)
case serverError(response: HTTPURLResponse, data: Data)
case custom(response: HTTPURLResponse, data: Data)
}
class MockHTTPClient: HTTPClient {
func publisher(for request: URLRequest) -> AnyPublisher<HTTPResponse, Swift.Error> {
let json = #"{"id": 1, "name": "Some Corporation"}"#.data(using: .utf8)!
let url = URL(string: "https://api.my.com/companies")!
let httpUrlResponse = HTTPURLResponse(url: url, statusCode: 200, httpVersion: nil, headerFields: nil)!
let response: HTTPResponse = .success(response: httpUrlResponse, data: json)
return Just(response)
.mapError { _ in "no error" }
.eraseToAnyPublisher()
}
}
Assemble:
let httpClient = MockHTTPClient()
let getCompany = GetCompany(httpClient: httpClient)
let viewModel = CompanyViewModel(getCompany: getCompany)
viewModel.load()
In Objective-C I often use the pattern of using a static void* as an identification tag. At times these tags are only used within that function/method, hence it's convenient to place the variable inside the function.
For example:
MyObscureObject* GetSomeObscureProperty(id obj) {
static void* const ObscurePropertyTag = &ObscurePropertyTag;
MyObscureObject* propValue = objc_getAssociatedObject(id,ObscurePropertyTag);
if(!propValue) {
propValue = ... // lazy-instantiate property
objc_setAssociatedObject(obj,ObscurePropertyTag,propValue, OBJC_ASSOCIATION_RETAIN_NONATOMIC)
}
return propValue;
}
The question is, how to write the ObscurePropertyTag private-constant-pointer-to-itself in Swift? (Preferrably 2.1 but future already-announced versions should be okay)
I've looked around and it seems that I have to put this ObscurePropertyTag as a member variable and there doesn't seem to be a way around it.
Unlike (Objective-)C, you cannot take the address of an
uninitialized variable in Swift. Therefore creating a self-referencing
pointer is a two-step process:
Swift 2:
var ptr : UnsafePointer<Void> = nil
withUnsafeMutablePointer(&ptr) { $0.memory = UnsafePointer($0) }
Swift 3:
var ptr = UnsafeRawPointer(bitPattern: 1)!
ptr = withUnsafePointer(to: &ptr) { UnsafeRawPointer($0) }
For your purpose, is it easier to use the address of a global variable with &, see for
example
Is there a way to set associated objects in Swift?.
If you want to restrict the scope of the "tag" to the function itself
then you can use a static variable inside a local struct. Example:
func obscureProperty(obj : AnyObject) -> MyObscureObject {
struct Tag {
static var ObscurePropertyTag : Int = 0
}
if let propValue = objc_getAssociatedObject(obj, &Tag.ObscurePropertyTag) as? MyObscureObject {
return propValue
}
let propValue = ... // lazy instantiate property value
objc_setAssociatedObject(obj, &Tag.ObscurePropertyTag,propValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
return propValue
}
Try this:
var GetSomeObscureProperty: MyObscureObject = nil
withUnsafePointer(& GetSomeObscureProperty) {
GetSomeObscureProperty = MyObscureObject($0)
}
In short
let GetSomeObscureProperty = UnsafePointer<()>()