We Keep Coding

C# - Try something twice if if-statement is true

I have a code parsing a website and adding some values to a list. Sometimes I need to parse the website two times and add the second parsevalues to the same list.
This is some of the code:
public async Task<IEnumerable<Info>>....
{
var values = new List<Info>();
var request = something;
var request_rewritten = rewritten request to run the second time;
......
if request contains something do all the under two times. Both for the request and the rewritten request and add it to result.
......
var response = await RequestBytes(request);
var results = Encoding.GetEncoding("iso-8859-1").GetString(response.Content);
_fDom = results;
try
{
do something and a lot of code
......
values.Add(result);
return result
}
}
If request contains something I need try try a second time. Both for the original request and the rewritten request and add both to the result. Can this be done?

You can follow this pattern. Add an additional parameter to your method indicating retries remaining.
void DoSomething(arg1, arg2, int retriesRemaining = 0)
{
try
{
DoWork();
}
catch
{
if (retriesRemaining) DoSomething(arg1, arg2, --retriesRemaining);
}
}

I suppose if you want to avoid writing a method (which is the best answer to your question) you can use a flag:
bool bRunAgain = true;
while (bRunAgain)
{
// Your logic, check result and see if you need to run it again
if (your condition to run again == false)
{
bRunAgain = false;
}
}

Here is a common solution. Pass an action to this method and specify retries count
public bool ExecuteWithRetry(Action doWork, int maxTries=1) {
for(var tryCount=1; tryCount<=maxTries; tryCount++){
try{
doWork();
} catch(Exception ex){
if(tryCount==MaxTriex){
Console.WriteLine("Oops, no luck with DoWork()");
return false;
}
}
return true;
}
}
so in your method
void Something(){
....
if(ExecuteWithRetry(()=>NotTrustyMethod(), 2)) {
//success
} else {
//fail
}
}
void NotTrustyMethod(){ ...}
This solution you can use for any case where you need retry option for methods with any type of arguments (or without them)

GET Request dont save data

I'm trying to save some data from a GET request. I use StartCoroutine to request and I use Lambda expression for save the data.
My Code is this:
Using UnityEngine;
using System.Collections;
public class Test : MonoBehaviour {
// Use this for initialization
public void Start () {
string url1 = "http://localhost/virtualTV/query/?risorsa=";
string ciao = "http://desktop-pqb3a65:8080/marmotta/resource/ef299b79-35f2-4942-a33b-7e4d7b7cbfb5";
url1 = url1 + ciao;
WWW www1 = new WWW(url1);
var main=new JSONObject(JSONObject.Type.OBJECT);
var final= new JSONObject(JSONObject.Type.OBJECT);;
StartCoroutine(firstParsing((value)=>{main = value;
final= main.Copy();
Debug.Log(main);
}));
Debug.Log(final);
}
public IEnumerator firstParsing( System.Action<JSONObject> callback)
{
string url2 = "http://localhost/virtualTV/FirstQuery/?risorsa=";
string ciao = "http://desktop-pqb3a65:8080/marmotta/resource/ef299b79-35f2-4942-a33b-7e4d7b7cbfb5";
url2 = url2 + ciao;
WWW www2 = new WWW(url2);
yield return www2;
string json = www2.text;
//Parsing del json con creazione di un array
var firstjson = new JSONObject(json);
var tempVideo = new JSONObject(JSONObject.Type.OBJECT);
var array2 = new JSONObject(JSONObject.Type.OBJECT);
tempVideo.AddField ("id", firstjson.GetField ("id"));
tempVideo.AddField ("type", firstjson.GetField ("type"));
tempVideo.AddField ("url", firstjson.GetField ("url"));
array2.Add (tempVideo);
yield return array2;
callback (array2);
Debug.Log ("First Run" + array2);
}
When I try to use FINAL after the command,
final=main.copy()
it is empty. Can you help me to save the value in the variable final? Thanks all.

A coroutine's execution is spread across many frames. When a coroutine encounters a yield return statement, it returns to the calling method, which finishes executing, till the task finishes.
In your case, the Debug.Log(final) statement in Start executes as soon as yield return www2; in firstParsing is executed. The callback hasn't been called yet which is why final is empty.
To be able to access the value in final after it has been assigned outside the callback function, you will have to set a bool which is set to true after final is assigned in the callback. Something like this:
StartCoroutine(firstParsing((value)=>{main = value;
final= main.Copy();
Debug.Log(main);
isFinalAssigned = true;
}));
// In another method
if(isFinalAssigned)
{
// Access final
}
You will have to note that the above if statement is useful only in a method that is called periodically like Update. If you're accessing final in a method that is called only once (like OnEnable) you will have to wait for final to be assigned. You can use another coroutine for this task like
IEnumerator DoSomethingWithFinal()
{
while(!isFinalAssigned)
yield return null; // Wait for next frame
// Do something with final
}
The easiest way out is to consume (access) final in your callback.
EDIT2: From your comments, you can do something like the following. You will have to use coroutines, because blocking the main game thread is not a good idea.
private JSONObject final = null; // Make final a field
Wherever you use final, you have two options.
Use a null check if(final == null) return; This can be impractical.
Wait for final to be assigned in a coroutine and do something as a callback. This is the only way you can do what you want cleanly.
Look below for the implementation.
// Calls callback after final has been assigned
IEnumerator WaitForFinal(System.Action callback)
{
while(final == null)
yield return null; // Wait for next frame
callback();
}
// This whole method depends on final.
// This should be similar to your method set up if you have
// good coding standards (not very long methods, each method does only 1 thing)
void MethodThatUsesFinal()
{
if (final == null)
{
// Waits till final is assigned and calls this method again
StartCoroutine(WaitForFinal(MethodThatUsesFinal));
return;
}
// use final
}

Find Item in List<T> That Threw Exception

I have inherited a WCF web service application that requires to have much better error tracking. What we do is query data from one system (AcuODBC), and send that data to another system (Salesforce). This query will return 10's of thousands of complex objects as a List<T>. We then process this List<T> in batches of 200 records at a time to map the fields to another object type, then send that batch to Salesforce. After this is completed, the next batch starts. Here's a brief example:
int intStart = 0, intEnd = 200;
//done in a loop, snipped for brevity
var leases = from i in trleases.GetAllLeases(branch).Skip(intStart).Take(intEnd)
select new sforceObject.SFDC_Lease() {
LeaseNumber = i.LeaseNumber.ToString(),
AccountNumber = i.LeaseCustomer,
Branch = i.Branch
(...)//about 150 properties
//do stuff with list and increment to next batch
intStart += 200;
However, the problem is if one object has a bad field mapping (Invalid Cast Exception), I would like to print out the object that failed to a log.
Question
Is there any way I can decipher which object of the 200 threw the exception? I could forgo the batch concept that was given to me, but I'd rather avoid that if possible for performance reasons.

This should accomplish what you are looking for with very minor code changes:
int intStart = 0, intEnd = 200, count = 0;
List<SDFC_Lease> leases = new List<SDFC_Lease>();
//done in a loop, snipped for brevity
foreach(var i in trleases.GetAllLeases(branch).Skip(intStart).Take(intEnd)) {
try {
count++;
leases.Add(new sforceObject.SFDC_Lease() {
LeaseNumber = i.LeaseNumber.ToString(),
AccountNumber = i.LeaseCustomer,
Branch = i.Branch
(...)//about 150 properties);
} catch (Exception ex) {
// you now have you culprit either as 'i' or from the index 'count'
}
}
//do stuff with 'leases' and increment to next batch
intStart += 200;

I think that you could use a flag in each set method of the properties of the class SFDC_Lease, and use a static property for this like:
public class SFDC_Lease
{
public static string LastPropertySetted;
public string LeaseNumber
{
get;
set
{
LastPropertySetted = "LeaseNumber";
LeaseNumber = value;
}
}
}
Plz, feel free to improve this design.

Parsing HTML in C# having a hard time with GetByteArrayAsync

public BarchartParser()
{
// Initialize list
StockSymbols = new List<string>();
// Add items
ParseBarchart();
}
this is the C'tor that calls the method
private async void ParseBarchart()
{
try
{
#region Get Html Document
// Get response from site
HttpClient http = new HttpClient();
var response = await http.GetByteArrayAsync(BARCHART_WEBSITE);
/* Break or W/e happens on this line ^^^ */
// Encode html response to UTF-8
string source = Encoding.GetEncoding(BARCHART_ENCODING)
.GetString(response, 0, response.Length - 1);
// Get html
HtmlDocument document = new HtmlDocument();
document.LoadHtml(source);
#endregion
#region Get Data From Table
// Get table containining stock info
HtmlNode table = document.DocumentNode.Descendants()
.Single<HtmlNode>
(
x => (x.Name == "table") &&
(x.Attributes["class"] != null) &&
(x.Attributes["class"].Value.Equals("datatable ajax")) &&
(x.Attributes["id"].Value.Equals("dt1"))
);
// Get 'tbody' element from table
HtmlNode tbody = table.Descendants("tbody").FirstOrDefault();
// Get all rows from the table
List<HtmlNode> allStocks = tbody.Descendants("tr").ToList();
// For each row, id is "td1_X" where X is the symbol of the stock
foreach (HtmlNode row in allStocks)
{
StockSymbols.Add(row.Attributes["id"].Value.ToString()
.Split(new char[] { '_' })[1]);
}
#endregion
}
catch
{
StockSymbols = new List<string>();
StockSymbols.Add("this didn't work");
}
}
And the code from a simple form application that uses this:
BarchartParser barchartData;
public Form1()
{
InitializeComponent();
barchartData = new BarchartParser();
}
private void Form1_Load(object sender, EventArgs e)
{
if (barchartData.StockSymbols != null && barchartData.StockSymbols.Count > 0)
MessageBox.Show(barchartData.StockSymbols[0]);
else
MessageBox.Show("barchartData.StockSymbols is null or count == 0");
this.Close();
}
Not exactly sure what's going on here. It worked for one time that I debugged and then it stopped working.
This code is part of a function that is called during a C'tor. When this throw or whatever happens,
It just continues to the next breakpoint that I set in debug mode... Anyone has a clue of what
May be the cause of this?
Edit: I know it's not a throw because the code in the catch block doesn't happen. It simply moves on
Just in general, i'm following this guide https://code.msdn.microsoft.com/Parsing-Html-using-C-721be358/sourcecode?fileId=122353&pathId=1834557721

You are not await-ing async method so only synchronous portion of the method (basically up to first real await) will be executed as part of your constructor call and the rest will eventually run on some arbitrary tread (possibly bringing process down in case of exception).
Generally you can't call async methods from constructor without good chance of deadlock if you try to call .Result or .Wait() (await vs Task.Wait - Deadlock?). As an option you can see if Fire-and-forget with async vs "old async delegate" works for your case.
Proper fix would be to move async operation from synchronous method (like constructor) to explicit async method and call it accordingly.
Hacky fix (with likley deadlock):
public BarchartParser()
{
...
ParseBarchart().Wait();
}

When an await statement throws an exception, only a try block can catch it. I suggest you add a try-catch or try-finally to catch the exception and handle it properly.

Why the objects do not get disposed when the scope ends while using Delegates

I have come across a weird scenario where the execution of a delegate continues even after the scope ends. I have also used GC.collect() at last but even it didn't work out.
I was using something related to selenium which keep executing till last, But You can print count.
Here I want to know the reason that why It keeps on executing the code even when it goes out of scope.
Here I meant automationActions, delAutomationAction go out of scope
class OptimixAutomation
{
public delegate void DelAutomationAction(ExeActions actionId);
static void Main(string[] args)
{
int numberOfInstances = Convert.ToInt32(ConfigurationManager.AppSettings["NumberOfInstances"]);
ExeActions actionId = (ExeActions)Convert.ToInt32(ConfigurationManager.AppSettings["ActionId"]);
for (int i = 0; i < numberOfInstances; i++)
{
AutomationActions automationActions = new AutomationActions();
DelAutomationAction delAutomationAction = new DelAutomationAction(automationActions.Login);
try
{
delAutomationAction.BeginInvoke(actionId: actionId, callback: null, #object: null);
}
catch (Exception e)
{
}
Thread.Sleep(10000);
}
Console.ReadKey();
}
}

AutomationActions automationActions = new AutomationActions();
DelAutomationAction delAutomationAction = new DelAutomationAction(automationActions.Login); - This line. As you can see, DelAutomationAction have reference to automationActions. Because DelAutomationAction is executed asynchronously, so it's still in "scope". And because GC can get to "automationActions" from "delAutomationAction", the first object won't be removed(and disposed).