const Validate.length({int lessThan, int greaterThan, int equalTo, int greaterThanEqualTo, int lessThanEqualTo, bool onUpdate: true, onInsert: true })

A validator for validating the length of a String.

Values passing through validators of this type must a String with a length that islessThan, greaterThan, lessThanEqualTo, equalTo, or [greaterThanEqualTo to the value provided for each argument.

Any argument not specified is not evaluated. A typical validator only uses one argument:

    @Validate.length(lessThan: 10)
    String foo;

All provided arguments are evaluated. Therefore, the following requires an input string to have a length to be between 6 and 10:

    @Validate.length(greaterThanEqualTo: 6, lessThanEqualTo: 10)
    String foo;

If onUpdate is true (the default), this validation is run on update queries. If onInsert is true (the default), this validation is run on insert queries.

Source 

const Validate.length(
    {int lessThan,
      int greaterThan,
      int equalTo,
      int greaterThanEqualTo,
      int lessThanEqualTo,
    bool onUpdate: true,
    onInsert: true})
    : this._(
          lessThan: lessThan,
          lessThanEqualTo: lessThanEqualTo,
          greaterThan: greaterThan,
          greaterThanEqualTo: greaterThanEqualTo,
          equalTo: equalTo,
          onUpdate: onUpdate,
          onInsert: onInsert,
          validator: _BuiltinValidate.length);