In the next chapters, I'll give you more **concrete recipes** to deploy FastAPI applications.

But for now, let's check these important **conceptual ideas**. These concepts also apply to any other type of web API. 💡

## Security - HTTPS

* Memory
* Previous steps before starting

You can use the same type declarations with `str`, `float`, `bool` and many other complex data types.

Several of these are explored in the next chapters of the tutorial.

## Order matters

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

But once you know the basic information of **HTTPS for developers** you can easily combine and configure different tools to help you manage everything in a simple way.

!!! danger
    Never store user's plaintext passwords. Always store a "secure hash" that you can then verify.

    If you don't know, you will learn what a "password hash" is in the [security chapters](security/simple-oauth2.md#password-hashing){.internal-link target=_blank}.

## Multiple models

Here's a general idea of how the models could look like with their password fields and the places where they are used:

You will see examples of this in the next chapters, about relational and NoSQL databases, security, etc.

## **FastAPI** compatibility

The simplicity of the dependency injection system makes **FastAPI** compatible with:

* all the relational databases

* `deprecated`

Validations specific for strings:

* `min_length`
* `max_length`
* `pattern`

In these examples you saw how to declare validations for `str` values.

import java.text.ParseException
import java.text.SimpleDateFormat
import java.util.Date
import java.util.TimeZone
import kotlin.reflect.KClass
import okio.ByteString

/**
 * Built-in adapters for reading standard ASN.1 types.
 */
internal object Adapters {
  val BOOLEAN =
    BasicDerAdapter(
      name = "BOOLEAN",
      tagClass = DerHeader.TAG_CLASS_UNIVERSAL,
      tag = 1L,
      codec =

   * ```
   */
  private val attributeTypeAndValue: BasicDerAdapter<AttributeTypeAndValue> =
    Adapters.sequence(
      "AttributeTypeAndValue",
      Adapters.OBJECT_IDENTIFIER,
      Adapters.any(
        String::class to Adapters.UTF8_STRING,
        Nothing::class to Adapters.PRINTABLE_STRING,
        AnyValue::class to Adapters.ANY_VALUE,
      ),
      decompose = {
        listOf(
          it.type,

    val bytes = "020132".decodeHex()
    assertThat(Adapters.INTEGER_AS_LONG.toDer(50L)).isEqualTo(bytes)
    assertThat(Adapters.INTEGER_AS_LONG.fromDer(bytes)).isEqualTo(50L)
  }

  @Test fun `decode negative integer`() {
    val bytes = "02019c".decodeHex()
    assertThat(Adapters.INTEGER_AS_LONG.fromDer(bytes)).isEqualTo(-100L)
    assertThat(Adapters.INTEGER_AS_LONG.toDer(-100L)).isEqualTo(bytes)
  }