meteor/meteor · error · MiniMongoQueryError

Only the i, m, and g regexp options are supported

Error message

Only the i, m, and g regexp options are supported

What it means

Thrown by the $regex operator when the accompanying $options string contains any character other than i, m, or g. minimongo only supports the JavaScript RegExp flags; MongoDB-specific flags like x (extended) and s (dotAll) are not implemented and are explicitly rejected.

Source

Thrown at packages/minimongo/common.js:185

      };
    },
  },
  $regex: {
    compileElementSelector(operand, valueSelector) {
      if (!(typeof operand === 'string' || operand instanceof RegExp)) {
        throw new MiniMongoQueryError('$regex has to be a string or RegExp');
      }

      let regexp;
      if (valueSelector.$options !== undefined) {
        // Options passed in $options (even the empty string) always overrides
        // options in the RegExp object itself.

        // Be clear that we only support the JS-supported options, not extended
        // ones (eg, Mongo supports x and s). Ideally we would implement x and s
        // by transforming the regexp, but not today...
        if (/[^gim]/.test(valueSelector.$options)) {
          throw new MiniMongoQueryError('Only the i, m, and g regexp options are supported');
        }

        const source = operand instanceof RegExp ? operand.source : operand;
        regexp = new RegExp(source, valueSelector.$options);
      } else if (operand instanceof RegExp) {
        regexp = operand;
      } else {
        regexp = new RegExp(operand);
      }

      return regexpElementMatcher(regexp);
    },
  },
  $elemMatch: {
    dontExpandLeafArrays: true,
    compileElementSelector(operand, valueSelector, matcher) {
      if (!LocalCollection._isPlainObject(operand)) {
        throw new MiniMongoQueryError('$elemMatch need an object');

View on GitHub (pinned to 5076d2f818)

Solutions

1. Use only i, m, and/or g: {field: {$regex: 'a.b', $options: 'im'}}.
2. Drop the unsupported flag, or pre-process the regex to simulate x (strip whitespace/comments) or s (transform . ) client-side.
3. If you need dotAll, rewrite the pattern to use [\s\S] instead of relying on the s flag.

Example fix

// before
collection.find({ body: { $regex: 'a.b', $options: 'is' } });
// after
collection.find({ body: { $regex: 'a[\s\S]b', $options: 'i' } });

function regexWithOptions(pattern, options) {
  if (options && /[^gim]/.test(options)) {
    throw new Error('Only i, m, g flags are supported by minimongo');
  }
  return { $regex: pattern, $options: options || '' };
}

function areValidRegexFlags(flags) {
  return typeof flags === 'string' && /^[gim]*$/.test(flags);
}

When it happens

Trigger: Using {field: {$regex: 'a.b', $options: 'is'}} or {field: {$regex: 'a.b', $options: 'x'}} in a minimongo query. The check /[^gim]/.test(valueSelector.$options) catches any unsupported flag.

Common situations: Copying a query from MongoDB shell that uses x or s flags; combining flags and including an unsupported one; passing options as a multi-char string with a typo.

Related errors

• $options needs a $regex
• $regex has to be a string or RegExp
• argument to $mod must be an array of two numbers
• $in needs an array
• cannot nest $ under $in

AI-assisted analysis of meteor/meteor@5076d2f818 (2026-08-13). Data as JSON: /api/errors/4cac54e6a32ca028. Report an issue: GitHub.