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From Nick Wellnhofer <>
Subject Re: [lucy-user] Getting search results as json objects
Date Thu, 01 Dec 2016 14:00:46 GMT
On 01/12/2016 02:52, Serkan Mulayim wrote:
> I am using the Lucy C library.
> I would like to ask if it is possible to get the HitDocs as Json Strings.
> I see that there is a dump method "LUCY_Doc_Dump" in Doc.c and HitDoc, can
> this be used for this. Can you elaborate on what "dump"  does? There is
> also S_to_json in json.c which expects a dump object to create a
> JsonString. Can I use them. If so how?
> Also what do serialize functions do in Doc classes.  Can I use them for
> this purpose?

Dump/Load and Serialize/Deserialize are private methods that are only used 
internally. The C library doesn't even implement Dump/Load. Serialization is 
used for Lucy's on-disk format and unlikely to be useful for anything else.

Lucy has an internal JSON encoder/decoder in Lucy::Util::Json. This is also a 
private API and only supports a subset of JSON. But you should be able to 
convert a Doc or HitDoc into a JSON string with the C library using 

     #include <Lucy/Util/Json.h>

     // Get_Fields returns a (non-incremented) Hash for the C bindings.
     Obj *hash = (Obj*)HitDoc_Get_Fields(doc);
     String *json = Json_to_json(hash);

The usual caveats for private APIs apply. They aren't supported officially and 
can change without notice. You can find some documentation for private APIs in 
the .cfh files.


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