Spring Expression Language

A number of components in CAS are able to take advantage of the Spring Expression Language syntax for their internal configuration. This is primarily useful when the component wishes to have access to system variables, environment properties or in general requires a more dynamic or programmatic strategy before it can be fully functional.

Expressions are expected to be encapsulated inside the ${...} syntax. Predefined variables are expected to be preceded with the # character. The following predefined variables are available:

Variable Description
systemProperties Map of system properties, loaded once typically on startup.
sysProps Same as above.
environmentVars Map of environment variables, loaded once typically on startup.
environmentVariables Same as above.
envVars Same as above.
env Same as above.
tempDir Path to the temp directory.
uuid Auto-generated UUID value.
randomNumber2 2-digit random number.
randomNumber4 4-digit random number.
randomNumber6 6-digit random number.
randomNumber8 8-digit random number.
randomString4 4-character random word.
randomString6 6-character random word.
randomString8 8-character random word.
localDateTime Current date/time using system’s default zone id.
localDateTimeUtc Current date/time using UTC.
localDate Current date using system’s default zone id.
localDateUtc Current date using UTC.
zonedDateTime Current zoned date using system’s default zone id.
zonedDateTimeUtc Current zoned date using UTC.
localStartWorkDay Start of current work day at 8am.
localEndWorkDay End of current work day at 5pm.
localStartDay Start of current day.
localEndDay End of current day.
zoneId Default system’s time zone id.

Examples

  • Assuming system property tier with a value of production is available, the configuration value file://${#systemProperties['tier']}/file.json translates to file://production/file.json
  • Assuming environment variable tier with a value of qa is available, the configuration value file://${#environmentVariables['tier']}/file.json translates to file://qa/file.json
  • Using ${#randomString6} translates to a 6-character random word, such as qemguz.
  • Using ${#randomNumber8} translates to a 8-digit random number, such as 75915283.