Mongodb duplicate key error. How do i get the error field from the error object as object?

Question

When trying to enter a new document in mongo with a value on a field that already exist in another document i get this when i iterate through the error object:

for(var att in err){
    console.log(att+": "+err[att]);
}

name: MongoError err: E11000 duplicate key error index: draw.users.$email_1 dup key: { : "[email protected]" } code: 11000 n: 0 ok: 1

So it tells me what i want to know, the problem is the email field. But can I get the offending field as a key/value rather than just a string?

olyjosh · Accepted Answer · 2017-02-19 20:12:58Z

5

Using split on the error message returned work for me this way

var x= err.errmsg.split("index:")[1].split("dup key")[0].split("_")[0];

answered Feb 19, 2017 at 20:12

olyjosh

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1 Comment

Hugo H Over a year ago

I added a .trim() because I had some space before the index name

null_radix · Accepted Answer · 2013-11-10 15:14:38Z

4

I use a regular expression. Like this

if(err){
   field = err.err.match(/\$(.*?)_/)[1]
}

Which is totally hacky but is working for me.

answered Nov 10, 2013 at 15:14

null_radix

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1 Comment

Anders Östman Over a year ago

Does not work on compound indexes like this: $client_1_email_1

Nisharg Shah · Accepted Answer · 2020-03-16 22:33:59Z

3

In the new version of MongoDB, you can also do that.

Where dupField is a duplicate field name and err.keyValue[dupField] is a duplicate field value.

const handleDuplicateFieldsDB = err => {
    const dupField = Object.keys(err.keyValue)[0];
    return `Duplicate field(${dupField}). Please use another value(${err.keyValue[dupField]})!`;
};

answered Mar 16, 2020 at 22:33

Nisharg Shah

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Comments

Discipol · Accepted Answer · 2013-07-09 12:17:16Z

0

If it collides, then making a find() for that query will return you the collision objects and you go from there.

answered Jul 9, 2013 at 12:17

Discipol

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4 Comments

WiredPrairie Over a year ago

You'd want to only do the find on indexed fields which were unique. It would require searching multiple fields potentially.

oivind Over a year ago

Thanks both of you. I'll guess I'll try findOne then before I do the save. Thought I could get away with using mongoError message. And I guess that should be possible in some way? The message tells me what I want, but as a string, that would be messy to do a regexp on I guess.

WiredPrairie Over a year ago

@oivind There'd still be a chance that the update would fail as another document could be saved between the call to findOne and the insert/update.

Discipol Over a year ago

depends on the library you use, some give detailed errors, some just 1 or 0. I use native mongo lib but I don't think is any more detailed than yours.

Florian · Accepted Answer · 2016-01-12 20:24:46Z

0

The error message doesn't give you the information that you are looking for :

name: MongoError err: E11000 duplicate key error index: draw.users.$email_1 dup key: { : "[email protected]" } code: 11000 n: 0 ok: 1

But it gives you enough to retrieve it.

You need to get the index that is causing the issue : "email_1" (use a regexp)

Then you need to ask the db about this index :

draw.users.getIndexKey("email_1")

answered Jan 12, 2016 at 20:24

Florian

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