I did not find the TryParse method for the Guid. I’m wondering how others handle converting a guid in string format into a guid type.
Guid Id;
try
{
Id = new Guid(Request.QueryString["id"]);
}
catch
{
Id = Guid.Empty;
}
This question is related to
c#
new Guid(string)
You could also look at using a TypeConverter.
If all you want is some very basic error checking, you could just check the length of the string.
string guidStr = "";
if( guidStr.Length == Guid.Empty.ToString().Length )
Guid g = new Guid( guidStr );
Unfortunately, there isn't a TryParse() equivalent. If you create a new instance of a System.Guid and pass the string value in, you can catch the three possible exceptions it would throw if it is invalid.
Those are:
I have seen some implementations where you can do a regex on the string prior to creating the instance, if you are just trying to validate it and not create it.
Guid.TryParse()
https://msdn.microsoft.com/de-de/library/system.guid.tryparse(v=vs.110).aspx
or
Guid.TryParseExact()
https://msdn.microsoft.com/de-de/library/system.guid.tryparseexact(v=vs.110).aspx
in .NET 4.0 (or 3.5?)
This will get you pretty close, and I use it in production and have never had a collision. However, if you look at the constructor for a guid in reflector, you will see all of the checks it makes.
public static bool GuidTryParse(string s, out Guid result)
{
if (!String.IsNullOrEmpty(s) && guidRegEx.IsMatch(s))
{
result = new Guid(s);
return true;
}
result = default(Guid);
return false;
}
static Regex guidRegEx = new Regex("^[A-Fa-f0-9]{32}$|" +
"^({|\\()?[A-Fa-f0-9]{8}-([A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}(}|\\))?$|" +
"^({)?[0xA-Fa-f0-9]{3,10}(, {0,1}[0xA-Fa-f0-9]{3,6}){2}, {0,1}({)([0xA-Fa-f0-9]{3,4}, {0,1}){7}[0xA-Fa-f0-9]{3,4}(}})$", RegexOptions.Compiled);
Unfortunately, there isn't a TryParse() equivalent. If you create a new instance of a System.Guid and pass the string value in, you can catch the three possible exceptions it would throw if it is invalid.
Those are:
I have seen some implementations where you can do a regex on the string prior to creating the instance, if you are just trying to validate it and not create it.
This will get you pretty close, and I use it in production and have never had a collision. However, if you look at the constructor for a guid in reflector, you will see all of the checks it makes.
public static bool GuidTryParse(string s, out Guid result)
{
if (!String.IsNullOrEmpty(s) && guidRegEx.IsMatch(s))
{
result = new Guid(s);
return true;
}
result = default(Guid);
return false;
}
static Regex guidRegEx = new Regex("^[A-Fa-f0-9]{32}$|" +
"^({|\\()?[A-Fa-f0-9]{8}-([A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}(}|\\))?$|" +
"^({)?[0xA-Fa-f0-9]{3,10}(, {0,1}[0xA-Fa-f0-9]{3,6}){2}, {0,1}({)([0xA-Fa-f0-9]{3,4}, {0,1}){7}[0xA-Fa-f0-9]{3,4}(}})$", RegexOptions.Compiled);
Unfortunately, there isn't a TryParse() equivalent. If you create a new instance of a System.Guid and pass the string value in, you can catch the three possible exceptions it would throw if it is invalid.
Those are:
I have seen some implementations where you can do a regex on the string prior to creating the instance, if you are just trying to validate it and not create it.
This will get you pretty close, and I use it in production and have never had a collision. However, if you look at the constructor for a guid in reflector, you will see all of the checks it makes.
public static bool GuidTryParse(string s, out Guid result)
{
if (!String.IsNullOrEmpty(s) && guidRegEx.IsMatch(s))
{
result = new Guid(s);
return true;
}
result = default(Guid);
return false;
}
static Regex guidRegEx = new Regex("^[A-Fa-f0-9]{32}$|" +
"^({|\\()?[A-Fa-f0-9]{8}-([A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}(}|\\))?$|" +
"^({)?[0xA-Fa-f0-9]{3,10}(, {0,1}[0xA-Fa-f0-9]{3,6}){2}, {0,1}({)([0xA-Fa-f0-9]{3,4}, {0,1}){7}[0xA-Fa-f0-9]{3,4}(}})$", RegexOptions.Compiled);
use code like this:
new Guid("9D2B0228-4D0D-4C23-8B49-01A698857709")
instead of "9D2B0228-4D0D-4C23-8B49-01A698857709" you can set your string value
new Guid(string)
You could also look at using a TypeConverter.
If all you want is some very basic error checking, you could just check the length of the string.
string guidStr = "";
if( guidStr.Length == Guid.Empty.ToString().Length )
Guid g = new Guid( guidStr );
Guid.TryParse()
https://msdn.microsoft.com/de-de/library/system.guid.tryparse(v=vs.110).aspx
or
Guid.TryParseExact()
https://msdn.microsoft.com/de-de/library/system.guid.tryparseexact(v=vs.110).aspx
in .NET 4.0 (or 3.5?)
use code like this:
new Guid("9D2B0228-4D0D-4C23-8B49-01A698857709")
instead of "9D2B0228-4D0D-4C23-8B49-01A698857709" you can set your string value
This will get you pretty close, and I use it in production and have never had a collision. However, if you look at the constructor for a guid in reflector, you will see all of the checks it makes.
public static bool GuidTryParse(string s, out Guid result)
{
if (!String.IsNullOrEmpty(s) && guidRegEx.IsMatch(s))
{
result = new Guid(s);
return true;
}
result = default(Guid);
return false;
}
static Regex guidRegEx = new Regex("^[A-Fa-f0-9]{32}$|" +
"^({|\\()?[A-Fa-f0-9]{8}-([A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}(}|\\))?$|" +
"^({)?[0xA-Fa-f0-9]{3,10}(, {0,1}[0xA-Fa-f0-9]{3,6}){2}, {0,1}({)([0xA-Fa-f0-9]{3,4}, {0,1}){7}[0xA-Fa-f0-9]{3,4}(}})$", RegexOptions.Compiled);
new Guid(string)
You could also look at using a TypeConverter.
Source: Stackoverflow.com