CODEWITHSUNDEEP
javaspringmongodbspring-boot
Wasif Kirmani
Wasif Kirmani

Reputation: 1331

MongoError: Spring Boot throws E11000 duplicate key error

I have been trying to create a MongoDB application with Spring boot. But, before it starts it throws an exception of E11000 Dup. Key error in a collection. This error occurs at startup though I have verified all the points but, I didn't find any duplicate key in my data. My data structure looks likes

@Document( collection = "IT" )
public class ItemType {
    @Id
    private String      id;
    private IV[] iv;
}

public class IV {
    private String        value;
    private AP[] aps;
}

@Document( collection = "AP" )
public class AP {
    @Id
    private String     id;
    @Indexed( unique = true )
    private String     apc;
    private String     dim;
    private string foc;
}

Whenever I start my spring boot application it throws following exception:

E11000 duplicate key error collection: p.IT index: iv.aps.apc dup key: { : "AVI" }

My dataset is:

{
    "_id" : ObjectId("5e846c5c3584fe7c7831283e"),
    "iv" : [ 
        {
            "value" : "M",
            "aps" : [ 
                {
                    "apc" : "MOV"
                }, 
                {
                    "apc" : "AVI"
                }
            ]
        }, 

        {
            "value" : "N",
            "aps" : [ 
                {
                    "apc" : "MOV"
                }, 
                {
                    "apc" : "AVI"
                }
            ]
        }, 
        {
            "value" : "O",
            "aps" : [ 
                {
                    "apc" : "MOV"
                }
            ]
        }, 
        {
            "value" : "P",
            "aps" : [ 
                {
                    "apc" : "MOV"
                }
            ]
        }
    ]
}

I am new to MongoDB and it seems I am not making the data structure correctly. As I am willing to create reference to collection in a way that only few properties that I am using in another collection should be available there i.e. as you can see AP has more then 2 properties. But, I am using only apc which is needed by IV

Upvotes: 1

Views: 908

Answers (1)

Joe
Joe

Reputation: 28326

You have a unique index defined in class AP

    @Indexed( unique = true )
    private String     apc;

and then you have an array of AP object in class IV

private AP[] aps;

and an array of IV object in class IT

private IV[] iv;

The resulting index will enforce that no 2 documents can have apc fields with the same value. An index in MongoDB is structured as a set of k->v pairs, where the k is the value indexed field, and v is the internal document identifier (not the _id). If the same value appears multiple times in a single document, it will only be added to the index once.

The unique property is enforced at the index level, so a single document can have repeats of the value since it will only result in a single entry in the index, but no other document could then use that value because it would require adding a second copy of it in the index.

To bring this back around to your data, that sample document contains 2 different values for iv.aps.apc, MOV, and AVI. Since that is indexed with the unique option, no other document in that collection can have either of those values in that field.

Upvotes: 1

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