arrays - 如何将一个 json 文件中的 json 元素存储到另一个 json 文件中？
问题描述
我有一个 json 文件。这是它的外观示例：
*{
"_id": "5f70aa5c04d7a034fc19e8969b000599",
"contributors": null,
"coordinates": null,
"created_at": "Wed May 06 09:32:46 +0000 2020",
"display_text_range": [
13,
35
],
"entities": {
"hashtags": [],
"symbols": [],
"urls": [],
"user_mentions": [
{
"id": 1213834918263869400,
"id_str": "1213834918263869442",
"indices": [
0,
12
],
"name": "D!@n@(ام علي)",
"screen_name": "Dianamh2312"
}
]
},
"favorite_count": 0,
"favorited": false,
"filter_level": "low",
"geo": null,
"id": 1257966527946473500,
"id_str": "1257966527946473472",
"in_reply_to_screen_name": "Dianamh2312",
"in_reply_to_status_id": 1257909535752310800,
"in_reply_to_status_id_str": "1257909535752310784",
"in_reply_to_user_id": 1213834918263869400,
"in_reply_to_user_id_str": "1213834918263869442",
"is_quote_status": false,
"lang": "ar",
"place": {
"attributes": {},
"bounding_box": {
"coordinates": [
[
[
150.520929,
-34.118347
],
[
150.520929,
-33.578141
],
[
151.343021,
-33.578141
],
[
151.343021,
-34.118347
]
]
],
"type": "Polygon"
},
"country": "Australia",
"country_code": "AU",
"full_name": "Sydney, New South Wales",
"id": "0073b76548e5984f",
"name": "Sydney",
"place_type": "city",
"url": "https://api.twitter.com/1.1/geo/id/0073b76548e5984f.json"
},
"quote_count": 0,
"reply_count": 0,
"retweet_count": 0,
"retweeted": false,
"source": "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
"text": "@Dianamh2312 يسعد اوقاتك ام علي ",
"timestamp_ms": "1588757566807",
"truncated": false,
"user": {
"contributors_enabled": false,
"created_at": "Mon Dec 11 11:29:28 +0000 2017",
"default_profile": true,
"default_profile_image": false,
"description": "اَللّـهُمَّ اكْشِفْ هذِهِ الْغُمَّةَ عَنْ هذِهِ الاُْمَّةِ بِحُضُورِهِ ، وَ عَجِّلْ لَنا ظُهُورَهُ ، اِنَّهُمْ يَرَوْنَهُ بَعيداً وَ نَراهُ قَريباً.",
"favourites_count": 8338,
"follow_request_sent": null,
"followers_count": 5208,
"following": null,
"friends_count": 5097,
"geo_enabled": true,
"id": 940181735601455100,
"id_str": "940181735601455106",
"is_translator": false,
"lang": null,
"listed_count": 0,
"location": null,
"name": "iman",
"notifications": null,
"profile_background_color": "F5F8FA",
"profile_background_image_url": "",
"profile_background_image_url_https": "",
"profile_background_tile": false,
"profile_banner_url": "https://pbs.twimg.com/profile_banners/940181735601455106/1584734762",
"profile_image_url": "http://pbs.twimg.com/profile_images/1246607950392840192/QmN6Qf50_normal.jpg",
"profile_image_url_https": "https://pbs.twimg.com/profile_images/1246607950392840192/QmN6Qf50_normal.jpg",
"profile_link_color": "1DA1F2",
"profile_sidebar_border_color": "C0DEED",
"profile_sidebar_fill_color": "DDEEF6",
"profile_text_color": "333333",
"profile_use_background_image": true,
"protected": false,
"screen_name": "Hageiman",
"statuses_count": 4607,
"time_zone": null,
"translator_type": "none",
"url": null,
"utc_offset": null,
"verified": false
}
},
{
"_id": "5f70aa5c04d7a034fc19e8969b0007dd",
"contributors": null,
"coordinates": null,
"created_at": "Wed May 06 09:33:34 +0000 2020",
"display_text_range": [
12,
33
],
"entities": {
"hashtags": [],
"symbols": [],
"urls": [],
"user_mentions": [
{
"id": 1099969756805906400,
"id_str": "1099969756805906434",
"indices": [
0,
11
],
"name": "jamal199",
"screen_name": "jamal19918"
}
]
},
"favorite_count": 0,
"favorited": false,
"filter_level": "low",
"geo": null,
"id": 1257966726299316200,
"id_str": "1257966726299316230",
"in_reply_to_screen_name": "jamal19918",
"in_reply_to_status_id": 1257937052097745000,
"in_reply_to_status_id_str": "1257937052097744896",
"in_reply_to_user_id": 1099969756805906400,
"in_reply_to_user_id_str": "1099969756805906434",
"is_quote_status": false,
"lang": "ar",
"place": {
"attributes": {},
"bounding_box": {
"coordinates": [
[
[
150.520929,
-34.118347
],
[
150.520929,
-33.578141
],
[
151.343021,
-33.578141
],
[
151.343021,
-34.118347
]
]
],
"type": "Polygon"
},
"country": "Australia",
"country_code": "AU",
"full_name": "Sydney, New South Wales",
"id": "0073b76548e5984f",
"name": "Sydney",
"place_type": "city",
"url": "https://api.twitter.com/1.1/geo/id/0073b76548e5984f.json"
},
"quote_count": 0,
"reply_count": 0,
"retweet_count": 0,
"retweeted": false,
"source": "<a href=\"http://twitter.com/download/iphone\" rel=\"nofollow\">Twitter for iPhone</a>",
"text": "@jamal19918 صباح النور jamal ",
"timestamp_ms": "1588757614098",
"truncated": false,
"user": {
"contributors_enabled": false,
"created_at": "Mon Dec 11 11:29:28 +0000 2017",
"default_profile": true,
"default_profile_image": false,
"description": "اَللّـهُمَّ اكْشِفْ هذِهِ الْغُمَّةَ عَنْ هذِهِ الاُْمَّةِ بِحُضُورِهِ ، وَ عَجِّلْ لَنا ظُهُورَهُ ، اِنَّهُمْ يَرَوْنَهُ بَعيداً وَ نَراهُ قَريباً.",
"favourites_count": 8339,
"follow_request_sent": null,
"followers_count": 5208,
"following": null,
"friends_count": 5097,
"geo_enabled": true,
"id": 940181735601455100,
"id_str": "940181735601455106",
"is_translator": false,
"lang": null,
"listed_count": 0,
"location": null,
"name": "iman",
"notifications": null,
"profile_background_color": "F5F8FA",
"profile_background_image_url": "",
"profile_background_image_url_https": "",
"profile_background_tile": false,
"profile_banner_url": "https://pbs.twimg.com/profile_banners/940181735601455106/1584734762",
"profile_image_url": "http://pbs.twimg.com/profile_images/1246607950392840192/QmN6Qf50_normal.jpg",
"profile_image_url_https": "https://pbs.twimg.com/profile_images/1246607950392840192/QmN6Qf50_normal.jpg",
"profile_link_color": "1DA1F2",
"profile_sidebar_border_color": "C0DEED",
"profile_sidebar_fill_color": "DDEEF6",
"profile_text_color": "333333",
"profile_use_background_image": true,
"protected": false,
"screen_name": "Hageiman",
"statuses_count": 4608,
"time_zone": null,
"translator_type": "none",
"url": null,
"utc_offset": null,
"verified": false
}
},*我正在编写一个基本的json脚本来从这个文件中获取数据，其中lang="ar" 代码如下：
var fs = require('fs');
fs.readFile('./instance3_u.json', 'utf8', (err, jsonString) => {
if (err) {
console.log("Error reading file from disk:", err)
return
}
try {
const db = JSON.parse(jsonString)
var count = Object.keys(db.docs).length;
for (var i = 0; i < count; i++) {
if (db.docs[i].lang === "ar") {
console.log(db.docs[i]._id, '\n', db.docs[i].text, '\n', db.docs[i].place.bounding_box.coordinates[0][0], '\n', db.docs[i].lang, '\n')
var data_ar = {
id: db.docs[i]._id,
text: db.docs[i].text,
coordinates: db.docs[i].place.bounding_box.coordinates[0][0],
lang: db.docs[i].lang
}
var data = JSON.stringify(data_ar)
fs.writeFileSync('data_ar.json', data);
}
}
}
catch (err) {
console.log('Error parsing JSON string:', err)
}
})控制台打印所需的输出。当我尝试将此输出存储到另一个名为data_ar的 json 文件中时，它只是给了我i的最后一个值。我想存储我在控制台中打印的全部数据
我如何实现这一目标？
解决方案
fs.writeFileSync('data_ar.json', data);每次调用时，此行都会创建该 data_ar.json 文件。所以这就是为什么你只看到数组中的最后一个。您应该改用fs.appendFileSync方法。
编辑：正如评论中所问的，在第一个示例中创建的 JSON 无效。为了使其有效，它需要是一个数组。创建数组的更简单方法是过滤和映射原始数组，然后您可以使用writeFileSync，因为您只需执行 1 次写入操作。
const data = db.docs.filter(d=> d.lang === "ar").map(d=>
({
id: d._id,
text: d.text,
coordinates: d.place.bounding_box.coordinates[0][0],
lang: d.lang
}));
fs.writeFileSync('data_ar.json', data);
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