Spring Data: Unique field in MongoDB document

Question

let's say I have the following database entity:

@Document(collection = "users")
public class User {
    
    @Id
    private String id;

    private String firstname;

    private String lastname;

    private String email; 

}

How can I enforce the field email to be unique? That means MongoDB should check if a user record with this email address already exists when the application tries to save the entity.

I found this stackoverflow question/answer which helped me on this: https://stackoverflow.com/a/62217147/845117 (None of the answers here helped me; running Springboot 3.0.2, Mongo) — Dirk Schumacher, Mar 28 '23 at 20:55

score 22 · Answer 1 · answered Oct 11 '19 at 10:25

22

Mongodb needs to create and index a field in order to know whether the field is unique or not.

@Indexed(unique=true)
private String email;

answered Oct 11 '19 at 10:25

V.Aggarwal

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2

I tried this and the mongo driver didn't do any enforcing to make this unique – David Apr 21 '20 at 21:30
@David : Did you create index on mongo side as well? – Vishnu Dahatonde May 11 '20 at 05:03

score 10 · Answer 2 · edited Aug 18 '21 at 06:58

10

This worked for me, but you have to delete your database and then re-run your application

 spring.data.mongodb.auto-index-creation=true

edited Aug 18 '21 at 06:58

Mohamad Chamanmotlagh

333
1
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16

answered Jul 14 '21 at 14:54

Yassine Moumen

109
1
4

@Moumen- How possible without deleting the database? – Praveen Kumar Verma Sep 29 '22 at 15:08

score 8 · Answer 3 · answered Sep 21 '20 at 11:38

First, use Indexed annotation above of your field in your model as shown below:

@Indexed(unique = true)
private String email;

Also, you should programmatically define your index. You should use the below code when defining your MongoTemplate.

mongoTemplate.indexOps("YOUR_COLLECTION_NAME").ensureIndex(new Index("YOUR_FEILD_OF_COLLECTION", Direction.ASC).unique());

For your case, you should use:

mongoTemplate.indexOps("users").ensureIndex(new Index("email", Direction.ASC).unique());

Why do we need to use the annotation if all the work is done on `mongoTemplate`? — Yves Calaci, Dec 11 '20 at 17:35

Mohamad Chamanmotlagh · Answer 4 · 2021-11-13T12:53:52.467

6

As of Spring Data MongoDB 3.0, automatic index creation is turned off by default. So basically, besides using @Indexed, you have to configure default indexing options. What you need to do is to make spring.data.mongodb.auto-index-creation=true in the application.properties file, and then @Indexed will work like a charm!

edited Nov 13 '21 at 12:53

answered Jul 01 '21 at 13:33

Mohamad Chamanmotlagh

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score 1 · Answer 5 · answered Jan 31 '22 at 11:19

You can try one of the below solutions, it worked for me.

Note: Please delete your db before you re-try with the below solutions.

Solution - 1

@Indexed(unique = true, background = true)
private String emailId;

Solution - 2

Add spring.data.mongodb.auto-index-creation=true to your application.properties file.

or

Add spring.data.mongodb.auto-index-creation:true to your yaml file

score 0 · Answer 6 · answered Jun 14 '22 at 08:58

If anyone has a custom Mongo configuration -> spring.data.mongodb.auto-index-creation:true won't work. Instead try adding this to your MongoConfig:

       @Override
       public boolean autoIndexCreation() {
       return true;
       }

It solved the problem for me....

Spring Data: Unique field in MongoDB document

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