CODEWITHSUNDEEP
elasticsearch
John
John

Reputation: 3115

Elasticsearch: Handling JSONs with arrays

I have a large JSON with many fields that contain arrays. Say one field is "Top" that contains many fields: "Middle1", "Middle2", "Middle3". Each of these "Middle" fields contains an array. Is there any simple way to search every element only within Middle1 and return back individual elements? When I try "Middle1.description":"blahblahblah" in a query with a match, elasticsearch returns all of Middle1. I've also tried changing the default mapping by elasticsearch to nested and it tells me: 

[object mapping [Middle1] can't be changed from non-nested to nested]

I'm at a loss here.

Also, if ES could search through all of these arrays and return individual elements that match, that would be fantastic.

Upvotes: 0

Views: 3217

Answers (2)

François SAMIN
François SAMIN

Reputation: 360

May be a bit late, but i encountered the same issue [object mapping [...] can't be changed from non-nested to nested] on a "Nested" mapped field, that I 've resolved by setting the mapping to "Object".

Example with springdata annotation :

@Field(type = FieldType.Object)
List<Component> components;

Upvotes: 1

javanna
javanna

Reputation: 60205

You can only make backward compatible changes the mapping. That's why you get back that error when trying to change the type of an object to nested. You should reindex your document and create the nested type upfront, before actually indexing any document. You can either submit your mapping through the create index api while creating the index or update it afterwards using the put mapping api.

Even using nested documents, you are always going to get back the whole document that you indexed. What the nested type allows is to make a distinction between the different children and return proper matches, that belong to the same child. That's useful when mapping one to many relations and you make multiple queries on the children at the same time. Have a look at the following articles to know more:

http://euphonious-intuition.com/2013/02/managing-relations-in-elasticsearch/ http://www.spacevatican.org/2012/6/3/fun-with-elasticsearch-s-children-and-nested-documents/

As mentioned in the article parent/child is the alternative to nested documents, less performant but more flexible. Parents and children can be indeed independently and you can either retrieve children querying the parents or parents querying the children.

I'm not sure though if parent/child is going to be helpful in your case, especially if your problem is only to return the matching children.

Upvotes: 2

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