当您的 API 应用调用*外部 API*时，这个过程被称为“回调”。因为外部开发者编写的软件会先向您的 API 发送请求，然后您的 API 再进行*回调*，向*外部 API*发送请求（很可能也是该开发者创建的）。

此时，我们需要存档外部 API 的*信息*，比如应该有哪些*路径操作*，请求体应该是什么，应该返回什么响应等。

## 使用回调的应用 { #an-app-with-callbacks }

示例如下。

假设要开发一个创建发票的应用。

发票包括 `id`、`title`（可选）、`customer`、`total` 等属性。

API 的用户（外部开发者）要在您的 API 内使用 POST 请求创建一条发票记录。

（假设）您的 API 将：

* 把发票发送至外部开发者的消费者
* 归集现金

        raise RuntimeError(response.text)
    return data


def get_graphql_question_discussion_edges(
    *,
    settings: Settings,
    after: str | None = None,
) -> list[DiscussionsEdge]:
    with rate_limiter:
        data = get_graphql_response(
            settings=settings,
            query=discussions_query,
            after=after,
            category_id=questions_category_id,
        )

	AssertAssociationCount(t, user2, "Manager", 0, "after clear")

	// unexist company id
	unexistCompanyID := company.ID + 9999999
	user = User{Name: "invalid-user-with-invalid-belongs-to-foreign-key", CompanyID: &unexistCompanyID}
	if err := DB.Create(&user).Error; err == nil {
		tidbSkip(t, "not support the foreign key feature")
		t.Errorf("should have gotten foreign key violation error")

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"context"
	"errors"
	"fmt"
	pathutil "path"
	"runtime"
	"sort"
	"strings"
	"sync"
	"time"

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package sql

import (
	"bytes"
	"testing"

	"github.com/alecthomas/participle"
	"github.com/alecthomas/participle/lexer"
)

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * 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) 2010 The Android Open Source Project
 *
 * 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) 2008 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) 2013 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) 2012 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