} else if len(langs2) != 3 {
		t.Errorf("should only find only 3 languages, but got %+v", langs2)
	}

	DB.Clauses(clause.OnConflict{DoNothing: true}).Create(&langs)
	var langs3 []Language
	if err := DB.Find(&langs3, "code LIKE ?", "upsert-slice%").Error; err != nil {
		t.Errorf("no error should happen when find languages with code, but got %v", err)

You can add custom exception handlers with <a href="https://www.starlette.io/exceptions/" class="external-link" target="_blank">the same exception utilities from Starlette</a>.

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()`:

    super(message);
  }

  /**
   * Creates a new instance with the given detail message and cause. Prefer to provide a
   * non-nullable {@code cause}, as many users expect to find one.
   */
  public ExecutionError(@CheckForNull String message, @CheckForNull Error cause) {
    super(message, cause);
  }

  /**
   * Creates a new instance with {@code null} as its detail message and the given cause. Prefer to

~~ or more contributor license agreements.  See the NOTICE file
~~ distributed with this work for additional information
~~ regarding copyright ownership.  The ASF licenses this file
~~ to you under the Apache License, Version 2.0 (the
~~ "License"); you may not use this file except in compliance
~~ with the License.  You may obtain a copy of the License at
~~
~~ http://www.apache.org/licenses/LICENSE-2.0
~~

 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *

/*
 * Written by Doug Lea and Martin Buchholz with assistance from
 * members of JCP JSR-166 Expert Group and released to the public
 * domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

/*
 * Source:
 * http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/test/tck-jsr166e/AtomicDoubleTest.java?revision=1.8
 * (Modified to adapt to guava coding conventions)
 */

package com.google.common.util.concurrent;

		// 403, but in situations where there is a dependency
		// with the caller to take the client offline purpose
		// fully it should make sure to respond with '412'
		// instead, see cmd/storage-rest-server.go for ideas.
		if c.HealthCheckFn != nil && resp.StatusCode == http.StatusPreconditionFailed {
			err = fmt.Errorf("Marking %s offline temporarily; caused by PreconditionFailed with drive ID mismatch", c.url.Host)

/*
 * Copyright (C) 2017 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2017 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0