Question

我试图从一个小的nodeJS应用程序中使用MongoDB中的聚合方法。我的目标是简单地计算特定键具有值的次数。我不在乎价值是什么。我只想为该密钥计算每个值。

以下是我尝试的内容：

const fs = require("fs");
const MongoClient = require("mongodb").MongoClient;

// Connection URL
const url = 'mongodb://localhost:27017/implant_history_audit_PROD';

// write to our mongo database
MongoClient.connect(url, (err, client) => {
    const db = client.db("implant_history_audit_PROD");
    db.collection("implants").aggregate([
        {
            $group: {
                _id: "$person_id",
                count: {
                    $sum: 1
                }
            }
        }
    ], (err, result) => {
        result.toArray().then(res => console.log(res), err => console.log(err));
        // fs.writeFileSync("patient_counts.txt", JSON.stringify(result));
    });
    client.close();
});

返回以下内容：[ { _id: null, count: 58059 } ]

以下是每个文档的架构：

{
  "IMPLANT_HISTORY_ID":0.000000,
  "IMPLANT_ITEM_ID":0.000000,
  "IMPLANT_ITEM_FT":"Some history free text",
  "IMPLANT_TYPE_CD":0.000000,
  "BIOLOGICAL_IMP_SRC_CD":0.000000,
  "NON_BIOLOGICAL_IMP_TYPE_CD":0.000000,
  "BODY_SITE_CD":0.000000,
  "COMMENTS":"This is a comment",
  "PERSON_ID":123456.000000,
  "ENCNTR_ID":0.000000,
  "EXPIRATION_DT_TM":"\/Date(0000-00-00T00:00:00.000+00:00)\/",
  "EXPLANT_DT_TM":"\/Date(0000-00-00T00:00:00.000+00:00)\/",
  "EXPLANT_DT_TM_PREC_FLAG":0,
  "EXPLANT_REASON_CD":0.000000,
  "IMPLANTED_FACILITY_CD":0.000000,
  "IMPLANTED_FACILITY_FT":"",
  "IMPLANTED_PRSNL_ID":0.000000,
  "IMPLANTED_PRSNL_FT":"",
  "IMPLANTED_DT_TM":"\/Date(1901-01-01T00:00:00.000-04:00)\/",
  "IMPLANTED_DT_TM_PREC_FLAG":3,
  "LOT_NUMBER_TXT":"",
  "MR_CLASSIFICATION_CD":0.000000,
  "PARENT_ENTITY_ID":0.000000,
  "PARENT_ENTITY_NAME":"",
  "PROCEDURE_CD":0.000000,
  "PROCEDURE_NOMEN_ID":0.000000,
  "PROCEDURE_FT":"",
  "IMPLANTED_QUANTITY":1,
  "SERIAL_NUMBER_TXT":"",
  "UDI_TXT":"",
  "DONOR_NUMBER_TXT":"",
  "MANUFACTURED_DT_TM":"\/Date(0000-00-00T00:00:00.000+00:00)\/",
  "MANUFACTURER_CD":0.000000,
  "MANUFACTURER_FT":"",
  "MANUFACTURER_MODEL_NBR_TXT":"",
  "ACTIVE_IND":1,
  "SURG_CASE_PROC_ID":0.000000,
  "DEVICE_IDENTIFIER_TXT":""
 }

我很困惑，因为每个文件都有一个＆＃34; person_id＆＃34;键。感谢您的见解。

修改
我还要提到文档中的键是大写的。但是，使用＆＃34; $ PERSON_ID＆＃34;导致脚本失败。我从中得到的错误是：

{MongoNetworkError：连接被破坏，无法实例化游标 at nextFunction（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：707：9）在AggregationCursor.Cursor.next（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：814：3）在AggregationCursor.Cursor._next（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb \ lib \ cursor.js：201：36） at fetchDocs（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb \ lib \ cursor.js：950：10）在C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb \ lib \ cursor.js：976：7 在handleCallback（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：199：5） at nextFunction（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：804：5）在C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：686：7 在queryCallback（C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ cursor.js：263：16）在C：\ Users \ cgoepfrich2 \ Documents \ projects \ implant migration \ PROD \ node_modules \ mongodb-core \ lib \ connection \ pool.js：541：18 名称：＆＃39; MongoNetworkError＆＃39;，消息：＆＃39;连接被破坏，无法实例化光标＆＃39; }

MongoDB collection.aggregate用于检索计数

0 个答案: