Develop Reference

Swift HTTP session not sending actual Request

So I have some Swift code that send a request to my local host
//
// ContentView.swift
// Shared
//
// Created by Ulto4 on 10/23/21.
//
import SwiftUI
struct ContentView: View {
var body: some View {
VStack{
Text("Hello, world!")
.padding()
Button(action : {
self.fu()
}, label: {
Image(systemName: "pencil").resizable().aspectRatio(contentMode:.fit)
})
}
}
func fu(){
let url = URL(string: "http://127.0.0.1:5000/232")
guard let requestUrl = url else { fatalError() }
var request = URLRequest(url: requestUrl)
request.httpMethod = "GET"
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
if let error = error {
print("Error took place \(error)")
return
}
if let response = response as? HTTPURLResponse {
print("Response HTTP Status code: \(response.statusCode)")
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
}
However, on my Flask app there are no get requests coming in and the function isn't running. There also isn't anything printing to the console.
I am fairly new to swift so I don't really know how to fix this.
Is there any other way to send requests in swift, if not, How would I fix this?

You are creating the URLSessionDataTask, but you never start it. Call task.resume(), e.g.
func performRequest() {
guard let url = URL(string: "http://127.0.0.1:5000/232") else {
fatalError()
}
let task = URLSession.shared.dataTask(with: url) { data, response, error in
if let error = error {
print("Error took place \(error)")
return
}
if let response = response as? HTTPURLResponse {
print("Response HTTP Status code: \(response.statusCode)")
}
}
task.resume() // you must call this to start the task
}
That having been said, a few caveats:
You are doing http rather than https. Make sure to temporarily enable insecure network requests with app transport settings, e.g.
You didn’t say if this was for macOS or iOS.
If running on physical iOS device, it will not find your macOS web server at 127.0.0.1 (i.e., it will not find a web server running on your iPhone). You will want to specify the IP number for your web server on your LAN.
If macOS, make sure to enable outbound network requests in the target’s “capabilities”:
You asked:
Is there any other way to send requests in swift?
It is probably beyond the scope of your question, but longer term, when using SwiftUI, you might consider using Combine, e.g., dataTaskPublisher. When running a simple “what was the status code” routine, the difference is immaterial, but when you get into more complicated scenarios where you have to parse and process the responses, Combine is more consistent with SwiftUI’s declarative patterns.
Let us consider a more complicated example where you need to parse JSON responses. For illustrative purposes, below I am testing with httpbin.org, which echos whatever parameters you send. And I illustrate the use of dataTaskPublisher and how it can be used with functional chaining patterns to get out of the mess of hairy imperative code:
struct SampleObject: Decodable {
let value: String
}
struct HttpBinResponse<T: Decodable>: Decodable {
let args: T
}
class RequestService: ObservableObject {
var request: AnyCancellable?
let decoder = JSONDecoder()
#Published var status: String = "Not started yet"
func startRequest() {
request = createRequest().sink { completion in
print("completed")
} receiveValue: { [weak self] object in
self?.status = "Received " + object.value
}
}
func createRequest() -> AnyPublisher<SampleObject, Error>{
var components = URLComponents(string: "https://httpbin.org/get")
components?.queryItems = [URLQueryItem(name: "value", value: "foo")]
guard let url = components?.url else {
fatalError("Unable to build URL")
}
return URLSession.shared.dataTaskPublisher(for: url)
.map(\.data)
.decode(type: HttpBinResponse<SampleObject>.self, decoder: decoder)
.map(\.args)
.receive(on: DispatchQueue.main)
.eraseToAnyPublisher()
}
}
struct ContentView: View {
#ObservedObject var requestService = RequestService()
var body: some View {
VStack{
Text("Hello, world!")
.padding()
Button {
requestService.startRequest()
} label: {
Image(systemName: "pencil").resizable().aspectRatio(contentMode:.fit)
}
Text(requestService.status)
}
}
}
But, like I said, it is beyond the scope of this question. You might want to make sure you get comfortable with SwiftUI and basic URLSession programming patterns (e.g., making sure you resume any tasks you create). Once you have that mastered, you can come back to Combine to write elegant networking code.
FWIW, like workingdog said, you could also use the new async-await rendition of data(for:delegate:). But when in the declarative world of SwiftUI, I would suggest Combine.

running a Python script from a Node.Js application

I absolutely love using Node.JS for my web projects but i also love using Python at the same time, so i have been wondering, if is it possible to run Python scripts from Node, for example my Node.JS backend calls a python script to retrive some data from a SQL Database and gives it back to Node (i know i can do that all in Node but just using an example). I thought about doing it this way
1.Node creates a Json files which contains the variable the Python script will use(for example name:Jon birthDate:1996)
2.It runs a python script that reads those variables from that Json file(so it searches for Jon born in 1996)
3.It deletes the Json file when its done
4.Rinse and Repeat
Would this be a good and safe way of doing this type of thing or are there any other ways of running and "modifiying" the Python script?

I had to build a node app, but for the backend calculations, it seemed better to use NumPy and Pandas, so I did what you are doing... in the end I found an npm package called python-shell.
It works via promises, so I'd call my calculation script, and also would do some clean up with another Python script if there were any errors.
Worked pretty good. Code was something like this:
const PythonShell = require('python-shell');
router.get('/calc', (req, res) => {
PythonShell.run('py/calculate.py', {pyPath: pyPath , args: [tmpPath],}, function(err, results) {
if (err) {
PythonShell.run('py/clean_up.py', {pyPath: pyPath, args: [tmpPath2]}, function(err, results2) {
if (err) throw err;
res.json(
{
message: "error: Running clean up",
ang: 0,
vec: 0,
}
);
});
} else {
let data = JSON.parse(results);
let message = data[0];
let ang = data[1];
let vec = data[2];
res.json(
{
message: message,
ang: ang,
vec: vec,
}
);
}
});
});

MeteorJS HTTP POST Request Connection Lost XMLHttpRequest

I am writing an application that integrates into a website that is already written in Meteor (I can't change that but I can add on to it). I am trying to send information from the Meteor application to my Flask server.
To do this I am using MeteorJs's HTTP module.
The code for this:
HTTP.post('http://127.0.0.1:5000/path', {
"content" : {"headers" : {"Content-Type": "application/json"}, "data": {time: getTime, data: getData()}}
},
(error, result) => {
if(error){
console.log(error);
console.log({time: getTime(), data: getData()})
}
else {
console.log(result);
}
}
)
getTime() and getData() both work independently outside this function, so they shouldn't be the source of error.
When I look at the JS console for when the event is being fired I receive the following message:
Error: Connection lost at XMLHttpRequest.xhr.onreadystateexchange and what was supposed to be sent to the Flask server.
When I look at the Flask server I see that it is receiving the post request with status code 200, but it seems like there is no data actually being received.
The code on the python end:
#app.route(r'path', methods=["POST"])
def get_data():
print(request.data)
print(request.args)
return "Hello World"
The print statements come out empty with this being shown on the console b'[object Object]' or ImmutableMultiDict([])
The Meteor app and the Flask app are both on different ports.
The problem I believe is on the MeteorJS side, since I used the curl linux function it works properly when I ping the flask server from there.
Is there a way to fix this error? If so how?

Hi "parameters" should be "data".
You can find all valid options in the docs.
Let me know if it works for you.
HTTP.post('http://127.0.0.1:5000/path', {
data : {time: getTime(), data: getData()}
}, (error, result) => {
if(error){
console.log(error);
console.log({time: getTime(), data: getData()})
} else {
console.log(result);
}
}
)

Need Example of passing Jasper Reports Parameters for REST v2 API using JSON

When I look at the documentation for passing parameters to the Jasper Report REST 2 API here: http://community.jaspersoft.com/documentation/jasperreports-server-web-services-guide/v550/running-report-asynchronously I see that I need to have a "parameters" dict. The example in the link shows the XML which is not all that useful since it's unclear exactly what the equivalent JSON should look like. The closest I could find is in this link: http://community.jaspersoft.com/documentation/jasperreports-server-web-services-guide/v56/modifying-report-parameters. Now, I am sending the equivalent of that to the server (and every other permutation I can think of), and I continue to get a "400 Client Error: Bad Request" back. I could really use an exact example of the python code to generate the required "parameters" parameter for say "my_parameter_1="test_value_1".
Here is my current POST data (with a few params missing for brevity). I know this is correct since the report works fine if I omit the "parameters" parameter:
{
'outputFormat': 'pdf',
'parameters': [{'name': 'ReportID', 'value': ['my_value_1']}],
'async': 'true',
'pages': '',
'interactive': 'false'
}

Nice Job there Staggart. I got it now. Because I wasn't reading with max. scrutinity, I wasted some additional time. So the interested coder is not only advised to be aware of the nested, syntactictally interesting reportParameter-property, but especially that the value-property inside that is an array. I suppose one could pass some form of Lists/Arrays/Collections here?
What irritated me was, if I should construct more than one "reportParameter" property, but that would be nonsense according to
Does JSON syntax allow duplicate keys in an object.
So just for the record, how to post multiple parameters:
{
"reportUnitUri": "/reports/Top10/Top10Customers",
"async": true,
"freshData": true,
"saveDataSnapshot": false,
"outputFormat": "pdf",
"interactive": false,
"ignorePagination": true,
"parameters": {
"reportParameter": [
{
"name": "DATE_START_STRING",
"value": ["14.07.2014"]
},
{
"name": "DATE_END_STRING",
"value": ["14.10.2014"]
}
]
}
}
If someone accidently is struggling with communicating with jasper via REST and PHP. Do yourself a favour and use the Requests for PHP instead of pure CURL. It even has a fallback for internally using Sockets instead of CURL, when latter isn't available.
Upvote for you Staggart.

OK, thanks to rafkacz1 # http://community.jaspersoft.com/questions/825719/json-equivalent-xml-post-reportexecutions-rest-service who posted an answer, I figured it out. As he report there, the required format is:
"parameters":{
"reportParameter":[
{"name":"my_parameter_1","value":["my_value_1"]}
]
}
Pay particular attention to the plurality of "reportParameter".

Here is an example that worked for me. Im using Python 2.7, and the community edition of Jaspersoft. Like the C# example above, this example also uses the rest v2 which made it very simple for me to download a pdf report quickly
import requests
sess = requests.Session()
auth = ('username', 'password')
res = sess.get(url='http://your.jasper.domain:8080/jasperserver/', auth=auth)
res.raise_for_status()
url = 'http://your.jasper.domain:8080/jasperserver/rest_v2/reports/report_folder/sub_folder/report_name.pdf'
params = {'Month':'2', 'Year':'2017','Project': 'ProjectName'}
res = sess.get(url=url, params=params, stream=True)
res.raise_for_status()
path = '/path/to/Downloads/report_name.pdf'
with open(path, "wb") as f:
f.write(res.content)

Here's a full example about generate a report using Rest V2, in my case it's running on C#:
try {
var server = "http://localhost:8080/jasperserver";
var login = server + "/rest/login";
var report = "/rest_v2/reports/organization/Reports/report_name.pdf";
var client = new WebClient();
//Set the content type of the request
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
//Set the username and password
NameValueCollection parametros = new NameValueCollection();
parametros.Add("j_username", "jasperadmin");
parametros.Add("j_password", "123456");
//Request to login
client.UploadValues(login, "POST", parametros);
//Get session cookie
string session = client.ResponseHeaders.Get("Set-Cookie");
//Set session cookie to the next request
client.Headers.Add("Cookie", session);
//Generate report with parameters: "start" and "end"
var reporte = client.DownloadData(server + report + "?start=2015-10-01&end=2015-10-10");
//Returns the report as response
return File(reporte, "application/pdf", "test.pdf");
}catch(WebException e){
//return Content("There was a problem, status code: " + ((HttpWebResponse)e.Response).StatusCode);
return null;
}

Creating a http-proxy that can modify the http response before sending it to the client

I'm using wget to grab a something from the web, but I don't want to follow a portion of the page. I thought I could set up a proxy that would remove the parts of the webpage I didn't want to be processed, before returning it to wget but I'm not sure how I would accomplish that.
Is there a proxy that lets me easily modify the http response in python or node.js?

There are several ways you could achieve this goal. This should get you started (using node.js). In the following example I am fetching google.com and replacting all instances of "google" with "foobar".
// package.json file...
{
"name": "proxy-example",
"description": "a simple example of modifying response using a proxy",
"version": "0.0.1",
"dependencies": {
"request": "1.9.5"
}
}
// server.js file...
var http = require("http")
var request = require("request")
var port = process.env.PORT || 8001
http.createServer(function(req, rsp){
var options = { uri: "http://google.com" }
request(options, function(err, response, body){
rsp.writeHead(200)
rsp.end(body.replace(/google/g, "foobar"))
})
}).listen(port)
console.log("listening on port " + port)

In nodejs I would fork node-http-proxy and customize the code to my needs.
Much simpler that writing an http proxy from scratch, IMHO.