JSON Schema - Regular Expressions (original) (raw)
The pattern andpatternProperties keywords use regular expressions to express constraints. The regular expression syntax used is from JavaScript (ECMA 262, specifically). However, that complete syntax is not widely supported, therefore it is recommended that you stick to the subset of that syntax described below.
- A single unicode character (other than the special characters below) matches itself.
.: Matches any character except line break characters. (Be aware that what constitutes a line break character is somewhat dependent on your platform and language environment, but in practice this rarely matters). To include newlines use the(.|\r?\n)*pattern which avoids the use of regex flags/modifiers and has good support across regex libraries.^: Matches only at the beginning of the string.$: Matches only at the end of the string.(...): Group a series of regular expressions into a single regular expression.|: Matches either the regular expression preceding or following the|symbol.[abc]: Matches any of the characters inside the square brackets.[a-z]: Matches the range of characters.[^abc]: Matches any character not listed.[^a-z]: Matches any character outside of the range.+: Matches one or more repetitions of the preceding regular expression.*: Matches zero or more repetitions of the preceding regular expression.?: Matches zero or one repetitions of the preceding regular expression.+?,*?,??: The*,+, and?qualifiers are all greedy; they match as much text as possible. Sometimes this behavior isn't desired and you want to match as few characters as possible.(?!x),(?=x): Negative and positive lookahead.{x}: Match exactlyxoccurrences of the preceding regular expression.{x,y}: Match at leastxand at mostyoccurrences of the preceding regular expression.{x,}: Matchxoccurrences or more of the preceding regular expression.{x,y}?,{x,}?: Non-greedy versions of the above expressions.- Use only standard escapes like
\n,\r,\tand keep in mind that you also need to do JSON escaping.
Example
The following example matches a simple North American telephone number with an optional area code:
The following example checks that the string starts with {{ and ends with }}and that it also allows multiline strings.