如何在带有Nest的Elasticsearch查询中比较文档的两个属性的十进制值？

Question

I have documents typed product indexed in elasticsearch index.

These product documents have 2 decimal values: NormalPrice , DiscountPrice .

I want to search documents which have NormalPrice > DiscountPrice .

I tried to construct a query like this:

q &= Query<ProductModel>.Range(u => u.Field(f => f.NormalPrice).GreaterThan(u.Field(f => f.DiscountPrice)));

First of all I'm not sure if my query is correct but if it is, GreaterThan function requires double values as I see.

What should I do? Is there an alternative way of doing this comparison with decimal values?

BTW changing property types to double is not an option. I have to use decimal.

Answer 1

Elasticsearch supports long , integer , short , byte , double and float numeric data types , so NEST maps decimal types to double by default.

To perform a comparison across document fields can be achieved with a script query

client.Search<ProductModel>(s => s
    .Query(q => q
        .Script(sn => sn
            .Inline("doc['normalPrice'].value > doc['discountPrice'].value")
        )
    )
);

Bear in mind that script queries can be expensive and potentially much slower than other queries depending on what you're doing. If this is a query that you need to run a lot, you might consider storing the comparison as a boolean field in the document and setting it up as a Property on your ProductModel type

public class ProductModel
{
    public decimal NormalPrice { get; set:}
    public decimal DiscountPrice { get; set:}
    public bool NormalPriceGreaterThanDiscountPrice 
    { 
        get { return NormalPrice > DiscountPrice; } 
    }
}

and then querying on that.