我试图更好地理解如何在JavaScript/React中处理嵌套的JSON对象。我通过GitLab API以如下形式获取数据：
const merge_requests = [
{
"id": 39329289,
"iid": 156,
"project_id": 231,
"title": "Repaired some Links",
"description": "",
"state": "merged",
"created_at": "2022-12-03T12:22:14.690Z",
"updated_at": "2022-12-03T12:22:20.060Z",
"merged_by": {
"id": 1000,
"username": "test.user",
"name": "test.user@gmail.de",
"state": "active",
"avatar_url": "",
"web_url": ""
},
"merge_user": {
"id": 2802,
"username": "tes.user",
"name": "test.user@gmail.de",
"state": "active",
"avatar_url": "",
"web_url": ""
},
"merged_at": "2022-12-03T12:22:20.072Z",
"closed_by": null,
"closed_at": null,
"assignees": [],
"assignee": null,
"reviewers": [],
"source_project_id": 231,
"target_project_id": 231,
"labels": [],
"squash_commit_sha": null,
"discussion_locked": null,
"should_remove_source_branch": null,
"force_remove_source_branch": null,
"reference": "!156",
"references": {
"short": "!156",
"relative": "!156",
"full": ""
},
"web_url": "",
"time_stats": {
"time_estimate": 0,
"total_time_spent": 0,
"human_time_estimate": null,
"human_total_time_spent": null
},
"squash": false,
"task_completion_status": {
"count": 0,
"completed_count": 0
},
"has_conflicts": false,
"blocking_discussions_resolved": true,
"approvals_before_merge": null
},
{
"id": 39329289,
"iid": 156,
"project_id": 231,
"title": "Repaired some Links",
"description": "",
"state": "merged",
"created_at": "2022-12-03T12:22:14.690Z",
"updated_at": "2022-12-03T12:22:20.060Z",
"merged_by": {
"id": 1000,
"username": "test.user",
"name": "test.user@gmail.de",
"state": "active",
"avatar_url": "",
"web_url": ""
},
"merge_user": {
"id": 2802,
"username": "test.user",
"name": "test.user@gmail.de",
"state": "active",
"avatar_url": "",
"web_url": ""
},
"merged_at": "2022-12-03T12:22:20.072Z",
"closed_by": null,
"closed_at": null,
"assignees": [],
"assignee": null,
"reviewers": [],
"source_project_id": 231,
"target_project_id": 231,
"labels": [],
"squash_commit_sha": null,
"discussion_locked": null,
"should_remove_source_branch": null,
"force_remove_source_branch": null,
"reference": "!156",
"references": {
"short": "!156",
"relative": "!156",
"full": ""
},
"web_url": "",
"time_stats": {
"time_estimate": 0,
"total_time_spent": 0,
"human_time_estimate": null,
"human_total_time_spent": null
},
"squash": false,
"task_completion_status": {
"count": 0,
"completed_count": 0
},
"has_conflicts": false,
"blocking_discussions_resolved": true,
"approvals_before_merge": null
},]我想循环遍历这个JSON中的所有对象（合并请求），并使用merge_user. name创建一个新数组。
console.log(merge_requests[0].merge_user.name);
console.log(merge_requests[1].merge_user.name);上面的日志返回了两个正确的值。但是，我不能循环通过JSON从数据创建一个新的数组，如下所示：
const arrTest = [];
for(var i = 0; i < Object.keys(merge_requests).length; i++)
{
var mergeUserName = merge_requests[i].merge_user.name;
arrTest.push(mergeUserName);
}
console.log(arrTest);
}上面的代码会导致以下错误：Uncaught (in promise) TypeError: resultData[i].merge_user is null
下面是一张图片：
我目前正在学习来自R的JS。我在使用JSON而不是 Dataframe 时遇到了巨大的问题，我找不到任何可以学习的文档。我将感谢任何建议/来源。
4条答案
按热度按时间k2arahey1#
不需要使用
Object.keys()，可以直接使用merge_requests.lengthmm5n2pyu2#
如果json中不存在对象，
merge_requests[i].merge_user?.name将返回undefined。h5qlskok3#
我复制并粘贴了你的代码和JSON，它工作得很好。
确保从ate API获取JSON后对其进行解析
typeof merge_requests应返回object，如果返回string，则执行以下操作：const parsedData = JSON.parse(merge_requests)和通过parsedData的循环khbbv19g4#
我检查了你的代码，运行正常.
检查您的api请求，您确定要等到它得到满足吗？