# Query Parameters and String Validations { #query-parameters-and-string-validations }

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

Let's take this application as example:

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}

FastAPI will use this return type to:

* **Validate** the returned data.
    * If the data is invalid (e.g. you are missing a field), it means that *your* app code is broken, not returning what it should, and it will return a server error instead of returning incorrect data. This way you and your clients can be certain that they will receive the data and the data shape expected.
* Add a **JSON Schema** for the response, in the OpenAPI *path operation*.

and do not modify the License. You may add Your own attribution notices 
within Derivative Works that You distribute, alongside or as an addendum to 
the NOTICE text from the Work, provided that such additional attribution 
notices cannot be construed as modifying the License.

You may add Your own copyright statement to Your modifications and may 

          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and

          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and

# CI Pipeline Configuration

## Open & import the project

In your IDEA, `File` - `Open`, select `.teamcity/pom.xml`, `import as project`, and you'll have a Maven project.

## Project structure

Mostly a standard Maven project structure. The entry point `settings.kts` defines the TeamCity project.

There are 3 subprojects in the TeamCity project hierarchy: `Check` for Gradle builds, `Promotion` for releasing Gradle versions, `Util` for miscellaneous utilities.

        # By default, queries listed here will override any specified in a config file.
        # Prefix the list here with "+" to use these queries and those in the config file.
        # queries: ./path/to/local/query, your-org/your-repo/queries@main

    - name: Compile with Gradle with Build Scan
      if: ${{ matrix.language == 'java' && github.repository_owner == 'gradle' }}

            "Last-Modified",
            formatDate(-1, TimeUnit.HOURS)!!,
            "Expires",
            formatDate(1, TimeUnit.HOURS)!!,
          ),
        body = "ABC.1",
      ),
    )
    server.enqueue(
      MockResponse(
        headers =
          headersOf(
            "Last-Modified",
            formatDate(-1, TimeUnit.HOURS)!!,
            "Expires",

### In production { #in-production }

In your production system, you probably have a frontend created with a modern framework like React, Vue.js or Angular.

And to communicate using WebSockets with your backend you would probably use your frontend's utilities.

Or you might have a native mobile application that communicates with your WebSocket backend directly, in native code.

In this case, `item_id` is declared to be an `int`.

/// check

This will give you editor support inside of your function, with error checks, completion, etc.

///

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr> { #data-conversion }