使用xml2js解析XML转JSON后存入MongoDB遭遇‘key $ must not start with $’错误的问题咨询

Ah, I've run into this exact issue before! The problem is that xml2js defaults to using $ as the key for XML element attributes, but MongoDB blocks any field names that start with $—that's why you're hitting that error. Here are two straightforward fixes:

Solution 1: Configure xml2js to Use a Valid Attribute Key #

The easiest fix is to tweak the xml2js parser settings to use a MongoDB-friendly key (like attributes) instead of $ for storing XML attributes. This avoids the problem entirely during parsing.

Update your parser initialization line to include the attrkey option:

const parser = new xml2js.Parser({ attrkey: 'attributes' }); // Replace default $ with 'attributes'

With this change, your parsed result will look like this (no more $ keys):

{ 
  PFA: { 
    Entity: [ 
      { 
        attributes: { id: '123', action: 'add', date: '31-Jul-2009' }, 
        ActiveStatus: [ 'Inactive' ] 
      } 
    ] 
  } 
}

You can now insert the result object directly into MongoDB without any errors.

Solution 2: Post-Process the Parsed JSON to Rename $ Keys #

If you can't modify the parser configuration (for example, if you need to keep the original structure elsewhere), you can recursively traverse the parsed object and rename all $ keys to something valid.

Add this helper function to your code:

function renameDollarKeys(obj) {
  if (Array.isArray(obj)) {
    return obj.map(item => renameDollarKeys(item));
  } else if (typeof obj === 'object' && obj !== null) {
    const cleanedObj = {};
    for (const key in obj) {
      // Replace $ with 'attributes' or any valid key name
      const newKey = key === '$' ? 'attributes' : key;
      cleanedObj[newKey] = renameDollarKeys(obj[key]);
    }
    return cleanedObj;
  }
  return obj; // Return primitive values as-is
}

Then apply this function to your parsed result before inserting into MongoDB:

parser.parseString(data, (err, result) => {
  const cleanedResult = renameDollarKeys(result); // Fix all $ keys
  // Proceed with MongoDB insertion using cleanedResult
  MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    var dbo = db.db("db");
    dbo.collection("entity").insertOne(cleanedResult, function(err, res) {
      if (err) throw err;
      console.log("1 document inserted");
      db.close();
    });
  });
});

Quick Note: Remove Unnecessary util.inspect Call #

I noticed your code uses util.inspect to convert the result to a string, but you don't actually use this string for the MongoDB insertion. You can safely delete that line—result is already a JavaScript object ready for insertion once the $ keys are fixed.

Content of the question来源于stack exchange，提问作者Steve