如何从NodeJS下载Mongo集合

时间:2018-01-15 15:48:46

标签: javascript node.js mongodb download

我有Mongo数据库,我想使用NodeJs API下载一个集合的所有注册表。我想下载像CSV或类似的东西。目前我有501426我的集合注册,所以当我调用.find()方法时,它返回此错误:

<--- Last few GCs --->
[15092:000001FE5E775B70]    95966 ms: Mark-sweep 1407.6 (1467.7) -> 1407.5 
(1451.2) MB, 1408.9 / 0.0 ms  last resort GC in old space requested
[15092:000001FE5E775B70]    97421 ms: Mark-sweep 1407.5 (1451.2) -> 1407.5 
(1451.2) MB, 1454.2 / 0.0 ms  last resort GC in old space requested
<--- JS stacktrace --->
==== JS stack trace =========================================
Security context: 000003F5F89A5EE1 <JSObject>
2: GetHash(aka GetHash) [native collection.js:1] [bytecode=000003F5F89D1721 
offset=51](this=0000011364082311 <undefined>,o=000002F6E28FAE89 <JSFunction 
wrapper (sfi = 000003167E337821)>)
4: set [native weak-collection.js:1] [bytecode=000003167E3380F9 offset=50]
(this=000001DB08591699 <JSWeakMap>,key=000002F6E28FAE89 <JSFunction wrapper 
(sfi = 000003167E337821)>,value=00000021B54F67F9 <J...
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory

我的代码是:

Collection.find({}).then(function(logs) {
  res.charset = 'utf-8';
          res.setHeader('Content-disposition', 'attachment; filename=' + 'filename.csv');
          res.setHeader('content-type', 'text/csv');
          csv
            .write(logs, {
              headers: true,
              transform: function(row) {
                return {
                  'Nivel': row.level,
                  'Metodo': row.method,
                  'IP': row.ip,
                  'URL': row.url,
                  'Status Code': row['status-code'],
                  'Usuario': row.user_email.email,
                  'Fecha': row.createdAt,
                  'Cuerpo': row.req_body,
                  'Consulta': row.req_query,
                  'Navegador': row['user-agent'],
                  'Datos Usuario': row.user_email,
                  'Aplicacion': row.referrer
                };
              }
            })
            .pipe(res);
})

此代码有效,但我想下载Collection的所有文档。抱歉我的英文。

由于

1 个答案:

答案 0 :(得分:1)

不是一次性转换/解析内存,而是应该一个接一个地处理。为此我们首先需要Stream,我们可以将数据写入:

 var csvStream = csv.createWriteStream({headers: true}),
csvStream.pipe(res); // directly pipe it to the user

然后我们可以按文档阅读集合文档,并将其传递给csv Transformer:

 Collection.find({}).stream({
    transform(row){
      return {
              'Nivel': row.level,
              'Metodo': row.method,
              'IP': row.ip,
              'URL': row.url,
              'Status Code': row['status-code'],
              'Usuario': row.user_email.email,
              'Fecha': row.createdAt,
              'Cuerpo': row.req_body,
              'Consulta': row.req_query,
              'Navegador': row['user-agent'],
              'Datos Usuario': row.user_email,
              'Aplicacion': row.referrer
            };
    }
  }).pipe(csvStream);