Re: Relationships in Mongodb

[Tito George]

There is no JOIN is mongo. So relationships wont help. You still can do that with third party api's like in case of java spring-data-mongo. But here API would be handling the relationship not in mongoDb level.

To take full advantage of mongo, data should be as de-normalized as possible. 

On Friday, April 19, 2013 5:04:04 PM UTC+5:30, Vamsi Popuri wrote:

Hi Everyone,

I am aware that, How to do (1-1, 1-m, m-m) relationships in MYSQL..But I confused in Mongodb. Because here there is no foreign keys concept. Therefore, Please can anyone provide one small example for understanding the relationships in mongodb..thanks for advance

[Vamsi Popuri]

I am using python ( Language), django (Framework), mongodb ( Database)....

[Sam Millman]

I would go against that and say that data should not be as de-normalised as possible. De-normalisation can actually be a difficult thing to manage in MongoDB but rather that you should model around how your indexes and queries will work.

As for handling relationships, since MongoDB has no server-side resolution of JOINs, you will need to do them manually in your application by actually storing the data you normally would for a JOIN and doing queries in the application to pull out data.

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[Vamsi Popuri]

If possible, then can you provide a small example about the relationships models in mongodb...may be country, state, city.

MYSQL:

Class Country(models.Model)

   name = models.Charfield(max_length=10)

Class State(models.Model)

  Country = models.Foreignkey(Country)

  name = models.Charfield(max_length=10)

Class City(models.Model)

  State = models.Foreignkey(State)

  name = models.Charfield(max_length=10)

My questions is how to create models in mongodb ? your help is really appreciable