# Query Parameters and String Validations

**FastAPI** allows you to declare additional information and validation for your parameters.

Let's take this application as example:

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params_str_validations/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9"
{!> ../../docs_src/query_params_str_validations/tutorial001.py!}
```

  /*
   * AbstractCollection fails the retainAll(null) test when the subject
   * collection is empty, but we'd still like to test retainAll(null) when we
   * can. We split the test into empty and non-empty cases. This allows us to
   * suppress only the former.
   */

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_nullCollectionReferenceEmptySubject() {
    try {

    IF "%%A"=="wrapperUrl" SET WRAPPER_URL=%%B
)

@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
if exist %WRAPPER_JAR% (
    if "%MVNW_VERBOSE%" == "true" (
        echo Found %WRAPPER_JAR%
    )
) else (

  // empty or missing, this rule matches all ports (traffic not restricted by port).
  // If this field is present and contains at least one item, then this rule allows
  // traffic only if the traffic matches at least one port in the list.
  // +optional
  repeated NetworkPolicyPort ports = 1;

  // List of destinations for outgoing traffic of pods selected for this rule.

  // * While dataSource only allows two specific types of objects, dataSourceRef
  //   allows any non-core object, as well as PersistentVolumeClaim objects.
  // * While dataSource ignores disallowed values (dropping them), dataSourceRef
  //   preserves all values, and generates an error if a disallowed value is
  //   specified.
  // * While dataSource only allows local objects, dataSourceRef allows objects

    body: Union[str, None] = None,
) -> Dict[str, Any]:
    headers = {"Authorization": f"token {settings.input_token.get_secret_value()}"}
    # some fields are only used by one query, but GraphQL allows unused variables, so
    # keep them here for simplicity
    variables = {
        "after": after,
        "category_id": category_id,
        "discussion_number": discussion_number,

option go_package = "k8s.io/api/admission/v1";

// AdmissionRequest describes the admission.Attributes for the admission request.
message AdmissionRequest {
  // UID is an identifier for the individual request/response. It allows us to distinguish instances of requests which are
  // otherwise identical (parallel requests, requests when earlier requests did not modify etc)

option go_package = "k8s.io/api/admission/v1beta1";

// AdmissionRequest describes the admission.Attributes for the admission request.
message AdmissionRequest {
  // UID is an identifier for the individual request/response. It allows us to distinguish instances of requests which are
  // otherwise identical (parallel requests, requests when earlier requests did not modify etc)

- Temporary credentials are short-term, as the name implies. They can be configured to last for anywhere from a few minutes to several hours. After the credentials expire, MinIO no longer recognizes them or allows any kind of access from API requests made with them.

You might remember that request bodies are also declared with Pydantic models.

Here **FastAPI** won't get confused because you are using `Depends`.

///

/// check

The way this dependency system is designed allows us to have different dependencies (different "dependables") that all return a `User` model.

We are not restricted to having only one dependency that can return that type of data.

///

## Other models