Pattern - sgpinkus/json-schema GitHub Wiki

A string instance is valid against pattern if and only if this keyword's value, which is a regular expression, matches the instance successfully.

NOTE: as per the actual definition, regular expression matching succeeds if it matches anywhere in the input. Many programming languages (Java, Python, others) have misnamed .matches or .match functions/methods which anchor regexes (either at the beginning, at the end, or both).

The value of this keyword MUST be a string. The string value MUST be a valid ECMA 262 regular expression.

See here for the ECMA 262 regular expression language.

(Note: this example is of course limited; regular expressions are an entire field of study by themselves which has spawned many books. If any, I'd recommend this one.)

Given this schema:

{
    "pattern": "[Ss]mith\\\\b"
}

the following values are valid:

• "My blacksmith produces excellent steel";
• "My name is John Smith, nice to meet you";

the following values are not valid:

• "I am no good at smithing, I'm afraid";
• "We visit the Smithes today".