Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`, and not some random string. This is especially useful for incoming data.

Without a data validation system, you would have to do all the checks by hand, in code.

    dependentRequired: Optional[Dict[str, Set[str]]] = None
    # Ref: JSON Schema Validation 2020-12: https://json-schema.org/draft/2020-12/json-schema-validation.html#name-vocabularies-for-semantic-c
    # Vocabularies for Semantic Content With "format"
    format: Optional[str] = None
    # Ref: JSON Schema Validation 2020-12: https://json-schema.org/draft/2020-12/json-schema-validation.html#name-a-vocabulary-for-the-conten

					if validationWhConf.Service == nil {
						t.Fatalf("expected validation service %s, got nil", tc.whSVC)
					}
					if validationWhConf.Service.Name != tc.whSVC {
						t.Fatalf("expected validation service %s, got %s", tc.whSVC, validationWhConf.Service.Name)
					}
					if validationWhConf.Service.Namespace != tc.istioNamespace {

-type")||"image";if(!f)throw new Error("Google reCaptcha site key is required.");var j=grecaptcha.render(e,{sitekey:f,theme:g,size:h,type:i,callback:function(a){b.find('[data-validation~="recaptcha"]').trigger("validation",a&&""!==a)},"expired-callback":function(){b.find('[data-validation~="recaptcha"]').trigger("validation",!1)}});d.valAttr("recaptcha-widget-id",j).hide().on("beforeValidation",function(a){a.stopImmediatePropagation()}).parent().append(e)})})},a(b).on("validatorsLoaded formValid...

## Rajouter plus de validation

Vous pouvez aussi rajouter un second paramètre `min_length` :

```Python hl_lines="9"
{!../../../docs_src/query_params_str_validations/tutorial003.py!}
```

## Ajouter des validations par expressions régulières

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

      }

    /**
     * Add a header with the specified name and value. Does validation of header names and values.
     */
    fun add(
      name: String,
      value: String,
    ) = commonAdd(name, value)

    /**
     * Add a header with the specified name and value. Does validation of header names, allowing
     * non-ASCII values.
     */
    fun addUnsafeNonAscii(

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                if "ValidationError" not in definitions:
                    definitions.update(
                        {
                            "ValidationError": validation_error_definition,
                            "HTTPValidationError": validation_error_response_definition,
                        }
                    )
            if route.openapi_extra:
                deep_dict_update(operation, route.openapi_extra)