Q: Querying by count of a slice field

[Nitzperetz]

Is there an easy way to query by the count of a slice field?

Example:

// ItemA holds a slice of strings
type ItemA struct {
	IDs  []string    `json:"items"`
}

I would like to have the top 10 ItemAs which have the most IDs related to them.
Therefore I would like to sort by the count of IDs field.
Is this scenario possible?

[mschoch]

Unfortunately there is no straightforward way to do this today.

The only way to make this possible is to index a field which contains the length of the IDs slice. You could hack it today by adding that field to your struct (obviously thats ugly and you don't want to do that, but that would work in bleve today). The other way to go about it is to create a custom analyzer which creates a new field (just in the index) containing the length of that slice. That isn't too hard, but the problem is the code we have today that uses reflection to walk through your structure will traverse into the contents of the slice, and what you need is something that is capable of looking at the slice as a whole (to calculate the length).

This is a good addition to the library that bleve needs.