{
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["body", "q"],
                    "msg": "String should match pattern '^fixedquery$'",
                    "input": "nonregexquery",
                    "ctx": {"pattern": "^fixedquery$"},
                }
            ]
        }
    ) | IsDict(

    {!> ../../../docs_src/query_params_str_validations/tutorial003_py310.py!}
    ```

## 🚮 🥔 🧬

👆 💪 🔬 <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">🥔 🧬</abbr> 👈 🔢 🔜 🏏:

=== "🐍 3️⃣.6️⃣ &amp; 🔛"

    ```Python hl_lines="11"
    {!> ../../../docs_src/query_params_str_validations/tutorial004.py!}
    ```

=== "🐍 3️⃣.1️⃣0️⃣ &amp; 🔛"

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["query", "item-query"],
                    "msg": "String should match pattern '^fixedquery$'",
                    "input": "nonregexquery",
                    "ctx": {"pattern": "^fixedquery$"},
                }
            ]
        }
    ) | IsDict(

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["query", "q"],
                    "msg": "String should match pattern '^fixedquery$'",
                    "input": "nonregexquery",
                    "ctx": {"pattern": "^fixedquery$"},
                }
            ]
        }
    ) | IsDict(

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["query", "item-query"],
                    "msg": "String should match pattern '^fixedquery$'",
                    "input": "nonregexquery",
                    "ctx": {"pattern": "^fixedquery$"},
                }
            ]
        }
    ) | IsDict(

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["query", "item-query"],
                    "msg": "String should match pattern '^fixedquery$'",
                    "input": "nonregexquery",
                    "ctx": {"pattern": "^fixedquery$"},
                }
            ]
        }
    ) | IsDict(

        {
            "detail": [
                {
                    "type": "string_pattern_mismatch",
                    "loc": ["body", "grant_type"],
                    "msg": "String should match pattern 'password'",
                    "input": "incorrect",
                    "ctx": {"pattern": "password"},
                }
            ]
        }
    ) | IsDict(

    ```

## Add regular expressions

You can define a <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">regular expression</abbr> `pattern` that the parameter should match:

=== "Python 3.10+"

    ```Python hl_lines="11"
    {!> ../../../docs_src/query_params_str_validations/tutorial004_an_py310.py!}
    ```

    GeneratorType: list,
    IPv4Address: str,
    IPv4Interface: str,
    IPv4Network: str,
    IPv6Address: str,
    IPv6Interface: str,
    IPv6Network: str,
    NameEmail: str,
    Path: str,
    Pattern: lambda o: o.pattern,
    SecretBytes: str,
    SecretStr: str,
    set: list,
    UUID: str,
    Url: str,
    AnyUrl: str,
}


def generate_encoders_by_class_tuples(

                        "grant_type": IsDict(
                            {
                                "title": "Grant Type",
                                "anyOf": [
                                    {"pattern": "password", "type": "string"},
                                    {"type": "null"},
                                ],
                            }
                        )
                        | IsDict(