A description of the Sitecore.Data.ID class and its methods and quirks along with a few code snippets.
Introduction
Namespace: Sitecore.Data
Assembly: Sitecore.Kernel.dll
The ID class in Sitecore is used to identify all types of item in Sitecore i.e. content items, templates, media items etc. It is a wrapper around .NET's own System.Guidstruct and has a property called Guidwhich returns a System.Guid. Internally Sitecore stores IDs in it's SQL Server database using the uniqueidentifiertype, but often stores IDs in string format e.g. when storing a link to an item within a droplink field.
The string format for IDs in Sitecore is equivalent to System.Guid.ToString("B").ToUpperInvariant()which is 32 upper case digits separated by hyphens and enclosed in braces.
E.g. {00000000-0000-0000-0000-000000000000}
ID.Parse Static Method (ID)
Sitecore IDs can be parsed from string or object and will accept the following:
ID.Parse("00000000000000000000000000000000"); //OK
ID.Parse("00000000-0000-0000-0000-000000000000"); //OK
ID.Parse("(00000000-0000-0000-0000-000000000000)"); //OK
ID.Parse("{00000000-0000-0000-0000-000000000000}"); //OK
ID.Parse("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}"); //OK
ID.Parse(""); //Throws FormatException
ID.Parse(" "); //Throws FormatException
ID.Parse("bob"); //Throws FormatException
ID.TryParse Static Method (Bool)
If the input source is not guaranteed to be a valid GUID format, then it is good practice to use ID.TryParse, which returns true if the input was valid and populates the result output parameter.
ID value;
ID.TryParse("00000000000000000000000000000000", out value); // false
ID.TryParse("00000000-0000-0000-0000-000000000000", out value); // true
ID.TryParse("(00000000-0000-0000-0000-000000000000)", out value); // false
ID.TryParse("{00000000-0000-0000-0000-000000000000}", out value); // true
ID.TryParse("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}", out value); // false
Note the subtle inconsistency with the ID.Parse method.
ID.IsID Static Method (Bool)
Returns true if the input string is a valid ID
ID.IsID("00000000000000000000000000000000"); // false
ID.IsID("00000000-0000-0000-0000-000000000000"); // true
ID.IsID("(00000000-0000-0000-0000-000000000000)"); // false
ID.IsID("{00000000-0000-0000-0000-000000000000}"); // true
ID.IsID("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}"); // false
ID.Encode Static Method (String)
Returns a string representation of the ID with no hyphens and no enclosing braces, format "N".
var id = new ID();
ID.Encode(id); // returns in the format "00000000000000000000000000000000"
ID.Decode Static Method (ID)
Returns an ID if the input string is in a valid format, otherwise throws FormatException.
ID.Decode("00000000000000000000000000000000"); // returns ID
ID.Decode("00000000-0000-0000-0000-000000000000"); // returns ID
ID.Decode("(00000000-0000-0000-0000-000000000000)"); // Throws FormatException
ID.Decode("{00000000-0000-0000-0000-000000000000}"); // returns ID
ID.Decode("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}"); // throws FormatException
ID.ParseArray Static Method (ID[])
This takes a list of pipe-separated IDs and returns an array of IDs.
ID.ParseArray("00000000000000000000000000000000|00000000000000000000000000000000"); // returns empty array
ID.ParseArray("00000000-0000-0000-0000-000000000000|00000000-0000-0000-0000-000000000000"); // returns array of two elements
ID.ParseArray("(00000000-0000-0000-0000-000000000000)|(00000000-0000-0000-0000-000000000000)"); // returns empty array
ID.ParseArray("{00000000-0000-0000-0000-000000000000}|{00000000-0000-0000-0000-000000000000}"); // returns array of two elements
ID.ParseArray("{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}|{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}"); // returns empty array
ID.ParseArray("|{00000000-0000-0000-0000-000000000000}||{00000000-0000-0000-0000-000000000000}|"); // returns array of two elements
ID.ParseArray("non|sense"); // returns empty array
ID.ParseArray((string)null, true); // returns null
ID.ParseArray((string)null, false); // returns empty array
ID.ArrayToString Static Method (String)
Converts an array of IDs into a pipe-separated string. Override method allows alternative separator.
var ids = new ID[] { new ID(), new ID() };
ID.ArrayToString(ids); //returns "{00000000-0000-0000-0000-000000000000}|{00000000-0000-0000-0000-000000000000}" (actual GUID values will differ!)
ID.ArrayToString(ids, ','); //returns "{00000000-0000-0000-0000-000000000000},{00000000-0000-0000-0000-000000000000}" (actual GUID values will differ!)
ShortID
This is a wrapper around the ID class which serves to read and write the ID in the 32 digit format (no hyphens and no enclosing braces or parentheses). This is useful when passing an ID via a query string. ID.ToShortID() returns a new instance of ShortID with the same internal GUID value. Likewise ShortID.ToID() returns a new ID with the same internal GUID value.
TemplateID
This class is essentially obsolete and should not be used.
GUIDs (in .NET) are case-insensitive
GUIDs in string form are a series of hexadecimal numbers and are therefore case-insensitive.
Be warned though, if you are talking to other non-.net systems this may not be the case!
Guid.ToString Format Types
The following format options can be used with System.Guid:
var guid = new Guid();
guid.ToString("N"); //Returns "00000000000000000000000000000000"
guid.ToString("D"); //Returns "00000000-0000-0000-0000-000000000000"
guid.ToString("P"); //Returns "(00000000-0000-0000-0000-000000000000)"
guid.ToString("B"); //Returns "{00000000-0000-0000-0000-000000000000}"
guid.ToString("X"); //Returns "{0x00000000,0x0000,0x0000,{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}}"
Other random facts
You can paste an item ID into the search box of the Content Editor to find an item (only works in regular Sitecore ID format).
Download
I have created a Gist on github with the code snippets here which you can run in LINQPad