# Global Dependencies { #global-dependencies }

For some types of applications you might want to add dependencies to the whole application.

Similar to the way you can [add `dependencies` to the *path operation decorators*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, you can add them to the `FastAPI` application.

In that case, they will be applied to all the *path operations* in the application:

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

///

::: fastapi.WebSocket
    options:

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

And you want to handle this exception globally with FastAPI.

You could add a custom exception handler with `@app.exception_handler()`:

{* ../../docs_src/handling_errors/tutorial003.py hl[5:7,13:18,24] *}

	tx = db.getInstance()
	tx.Statement.Distinct = true
	if len(args) > 0 {
		tx = tx.Select(args[0], args[1:]...)
	}
	return
}

// Select specify fields that you want when querying, creating, updating
//
// Use Select when you only want a subset of the fields. By default, GORM will select all fields.
// Select accepts both string arguments and arrays.
//
//	// Select name and age of user using multiple arguments

	if cb := createCallback.Get("c1"); reflect.DeepEqual(cb, c1) {
		t.Errorf("callbacks tests failed, got: %p, want: %p", cb, c1)
	}

	createCallback.Remove("c1")
	if cb := createCallback.Get("c2"); cb != nil {
		t.Errorf("callbacks test failed. got: %p, want: nil", cb)
	}
}

func TestCallbacksRemove(t *testing.T) {
	db, _ := gorm.Open(nil, nil)
	createCallback := db.Callback().Create()

          new Supplier<LongAddable>() {
            @Override
            public LongAddable get() {
              return new LongAdder();
            }
          };
    } catch (Throwable t) { // we really want to catch *everything*
      supplier =
          new Supplier<LongAddable>() {
            @Override
            public LongAddable get() {
              return new PureJavaLongAddable();
            }
          };

import com.google.common.annotations.GwtCompatible;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.annotations.NullMarked;

/**
 * Simple utility for when you want to create a {@link TearDown} that may throw an exception but
 * should not fail a test when it does. (The behavior of a {@code TearDown} that throws an exception

  @Override
  public int hashCode() {
    return delegate.hashCode();
  }

  private void validate() {
    // Don't use checkState(), because we don't want the overhead of generating the error message
    // unless it's actually going to be used; validate() is called for all set method calls, so it
    // needs to be fast.

 * </ul>
 *
 * <p>The main purpose of {@link #addListener addListener} is to support this chaining. You will
 * rarely use it directly, in part because it does not provide direct access to the {@code Future}
 * result. (If you want such access, you may prefer {@link Futures#addCallback
 * Futures.addCallback}.) Still, direct {@code addListener} calls are occasionally useful:
 *
 * {@snippet :
 * final String name = ...;
 * inFlight.add(name);

        return;
      }
    }
    // Execute the runnable immediately. Because of scheduling this may end up getting called before
    // some of the previously added runnables, but we're OK with that. If we want to change the
    // contract to guarantee ordering among runnables we'd have to modify the logic here to allow
    // it.
    executeListener(runnable, executor);
  }

  /**