FieldValues inference converts timestamp strings to date/times then to string in different format

[wewebber]

NEST/Elasticsearch.Net version: 2.4.1

Elasticsearch version: 2.33

Description of the problem including expected versus actual behavior:

If we have a string field holding a value that happens to look like a timestamp, and retrieve that field through a Fields() query, the field will get reformatted into a different form of date / time.

E.g. we have the mapping:

"mything" : {
    "myname" : {
       "type" : "string"
    }
}

fronted by the class:

public class MyThing
{
    [String]
    public string MyName { get; set; }
}

We insert the following mything:

new MyThing() { MyName = "2016-07-12T06:06:35.203Z" }

and do a search like:

var name = client.Search<MyThing>(sd => sd.Fields(fd => fd.Field(mt => mt.MyName)))
              .Fields.Select(fv => fv.Values<MyThing, string>(mt => mt.MyName)[0]).ToArray().[0]

We'll then find that name has a value like "12/07/2016 06:06:35" (depending I think on language settings).

The culprit I think is in

elasticsearch-net/src/Nest/CommonAbstractions/Fields/FieldValues.cs

Line 63 in cdea256

return array.ToObject<K>();

, where NEST uses Newtonsoft.Json.Linq.JArray to infer the type of the field. It infers it to be some sort of DateTime, then does a ToString() on that DateTime.

[Mpdreamz]

Thanks for reporting this @wewebber this has now been fixed in 2.x and 5.x 👍

[wewebber]

Excellent, thanks!