# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

## Version 4.8.0

_2020-07-11_

 *  New: Change `HeldCertificate.Builder` to use its own ASN.1 certificate encoder. This is part
    of our effort to remove the okhttp-tls module's dependency on Bouncy Castle. We think Bouncy
    Castle is great! But it's a large dependency (6.5 MiB) and its security provider feature
    impacts VM-wide behavior.

	m, ok := b.tryGrowByReslice(1)
	if !ok {
		m = b.grow(1)
	}
	b.buf[m] = c
	return nil
}

// WriteRune appends the UTF-8 encoding of Unicode code point r to the
// buffer, returning its length and an error, which is always nil but is
// included to match [bufio.Writer]'s WriteRune. The buffer is grown as needed;
// if it becomes too large, WriteRune will panic with [ErrTooLarge].

 * value that may be consumed only once and then closed. All other properties are immutable.
 *
 * This class implements [Closeable]. Closing it simply closes its response body. See
 * [ResponseBody] for an explanation and examples.
 */
class Response internal constructor(
  /**
   * The request that initiated this HTTP response. This is not necessarily the same request issued

    assertEquals(Country.class, bimap.valueType());
  }

  public void testIterationOrder() {
    // The enum orderings are alphabetical, leading to the bimap and its inverse
    // having inconsistent iteration orderings.
    Map<Currency, Country> map =
        ImmutableMap.of(
            Currency.DOLLAR, Country.CANADA,
            Currency.PESO, Country.CHILE,

/**
 * Generated tests for {@link Monitor}.
 *
 * <p>This test class generates all of its own test cases in the {@link #suite()} method. Every
 * {@code enterXxx}, {@code tryEnterXxx}, and {@code waitForXxx} method of the {@code Monitor} class
 * is analyzed reflectively to determine appropriate test cases based on its signature. Additional
 * ad hoc test cases can be found in {@link SupplementalMonitorTest}.
 *

* and in there, find the module `dependencies` (the file at `app/dependencies.py`)...
* and from it, import the function `get_token_header`.

That would refer to some package above `app/`, with its own file `__init__.py`, etc. But we don't have that. So, that would throw an error in our example. 🚨

But now you know how it works, so you can use relative imports in your own apps no matter how complex they are. 🤓

    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

<inherits name="com.google.common.annotations.Annotations" />
<inherits name="com.google.common.base.Base" />

  awk '/Streaming build results to/ {print $NF}' "$TFCI_OUTPUT_DIR/script.log" | uniq
}

# Print out any ResultStore URLs for Bazel invocations' results.
# Each failed target there will have its own representation, making failures
# easier to find and read.
function resultstore_extract {
  local PYTHON_BIN XML_PATH
  PYTHON_BIN=$(which python3 2>/dev/null || which python)

///

**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives its specific content and the same for `user`.

It will perform the validation of the compound data, and will document it like that for the OpenAPI schema and automatic docs.

## Singular values in body { #singular-values-in-body }