FileMaker Pro Custom Functions

/* Generate a Universally Unique Identifier (UUID) Parameters: 1 Generate a version 1 (MAC address) UUID with no hyphens 1h Generate a version 1 UUID with hyphens 4 Generate a version 4 (random) UUID with no hyphens 4h Generate a version 4 UUID with hyphens Requires: The NumToHex custom function by Jeremiah Small <http://www.briandunning.com/cf/216> Version 1 UUIDs are based on the current timestamp and MAC address and are in the form xxxxxxxx-xxxx-1xxx-yxxx-xxxxxxxxxxxx, where x is 0–F and y is 8–B. e.g. 7f23c000-b6fa-11ad-802a-136a8c2f7100. Version 4 UUIDs are randomly generated and in the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. e.g. f47ac10b-58cc-4372-a567-0e02b2c3d479. The advantages of using a UUID over a serial number is there’s no need to worry about the next value of a serial number or a serial number collision, forinstance when importing records. The downside is they’re not appropriate to expose to a user. UUID example: Dick and Harry both create records in their own copies of a database. Each record needs a unique serial number so they can be combined at a later date. After a total of 68,719,476,736 (2^36) records are created the probability of a collision is 0.0000000000000004 (4 × 10^−16) Further reading: <http://en.wikipedia.org/wiki/UUID> Caveats: - Because FileMaker’s clock resolution is only in seconds the version 1 UUID can return duplicates if called multiple times a second (there’s a 14-bit random number included which usually prevents this). - FileMaker 8.5–10.0v2 (and maybe earlier) have a bug where on some machines the random function returns the same sequence of random numbers every time FileMaker is restarted! This obviously corrupts the generation of unique identifiers. Using a version 1 UUID is safer in this instance. 10.0v3 fixes this. - I *think* I have the version 1 UUIDs correctly following the spec. Note they include local time (not UTC) and clock sequence is always random—both allowed but not recommended. Author: 2009-02-01 Tom Robinson <http://www.tomrobinson.co.nz/> Change History: 2009-02-06 Add patch parameter after discovery of FileMaker bug causing client’s machine to create duplicate UUIDs Generate lowercase UUIDs per RFC 4122 2009-02-11 Remove patch code and add generation of version 1 UUIDs as patch parameter was still returning duplicates Utilise DecToHex custom function 2009-08-07 Update docs to note random bug is fixed in 10.0v3 2010-05-12 DecToHex is now NumToHex Split last group in 4/4h from Random*281474976710656 (12 digits) to 2 × Random*16777216 (6+6 digits) as random function in 10.0v3 appears to have less precision—UUIDs were always ending in 0000 or ffff */ Case( Left(Type;1)="1"; Let( [ h=If(Right(Type;1)="h";"-";""); t=Lower(NumToHex((Get(CurrentTimeStamp)-49916304000)*10000000)) /* Subtract to move timestamp epoch from 0001-01-01T00:00:00 to 1582-10-15T00:00:00, multiply to get from seconds to hundred-nanosecond intervals */ ]; Right(t;8)&h& /* RFC 4122 time_low */ Middle(t;4;4)&h& /* time_mid */ "1"&Left(t;3)&h& /* time_hi_and_version */ Middle("89abb";Random*4+1;1)&Right("00"&Lower(NumToHex(Random*4096));3)&h& /* clock_seq_hi_and_reserved & clock_seq_low */ /* Note random can return 1 in which case result is 2nd ‘b’ or ‘000’ */ Substitute(GetValue(Get(SystemNICAddress);1);":";"") /* node */ ); Left(Type;1)="4"; Let( h=If(Right(Type;1)="h";"-";""); Lower( Right("0000000"&NumToHex(Random*4294967296);8)&h& Right("000"&NumToHex(Random*65536);4)&h& "4"&Right("00"&NumToHex(Random*4096);3)&h& Middle("89abb";Random*4+1;1)&Right("00"&NumToHex(Random*4096);3)&h& Right("00000"&NumToHex(Random*16777216);6)&Right("00000"&NumToHex(Random*16777216);6) ) ); "" )
 Then copy & paste into FileMaker Advanced's Edit Custom Function window.