The sample contract serves as a demonstration of general QVM logic.
It is capable of:
registering users into the database
storing the last registered user's name in the database
echoing the previous user's name to STDOUT
incrementing the total registered user count
storing above counter in the database
Sample code
using System;
public class Contract
{
private static String getEnv(String key, String deft) {
String? val = Environment.GetEnvironmentVariable(key);
if (val == null || val.Length == 0) {
return deft;
}
return val;
}
private static int atoi(String val) {
try
{
return Int32.Parse(val);
}
catch (FormatException)
{
return 0;
}
}
public static int Main(String[] args)
{
// THIS SAMPLE ONLY SUPPORTS THE "register" FUNCTION
if (args.Length == 2 && args[0] == "register") {
// GET THE CURRENT USER'S NAME OR DEFAULT TO "unknown" IF THIS IS THE FIRST CALL
String? previousName = getEnv("DB_USER_CURRENT", "unknown");
// GET THE TOTAL USER COUNT
int totalUserCount = atoi(getEnv("DB_TOTALUSERS", "0"));
// WRITE PREVIOUS USER NAME TO STDOUT
Console.Out.WriteLine($"OUT=prevname: {previousName}");
// UPDATE CURRENT USER NAME BY WRITING IT TO DB
Console.Out.WriteLine($"DBW=USER_CURRENT={args[1]}");
// STORE USER NAME UNDER A STORAGE SLOT FOR PERSISTENCE (CURRENT GETS OVERWRITTEN ON EACH CALL)
Console.Out.WriteLine($"DBW=USER_{totalUserCount}={args[1]}");
// INCREMENT THE TOTAL USER COUNT
Console.Out.WriteLine($"DBW=TOTALUSERS={totalUserCount+1}");
return 0;
}
if (args.Length >= 1) {
Console.Error.WriteLine("Wrong CMD: " + args[0]);
return 1;
}
Console.Error.WriteLine("Wrong args!");
return 1;
}
}
Save the contract
Open a text editor and save above sample contract as main.cs file.
