[Geojson] clarification on Feature id

Allan Doyle afdoyle at MIT.EDU
Sat Mar 15 18:20:33 PDT 2008

On Mar 15, 2008, at 7:52 PM, Mateusz Loskot wrote:

> Keith Jenkins wrote:
>> On Sat, Mar 15, 2008 at 5:54 PM, Christopher Schmidt
>> <crschmidt at metacarta.com> wrote:
>>> "id" isn't part of the spec. So, it's definitely not required,  
>>> though it
>>> probably makes sense to put it there, and most implementations  
>>> that I've
>>> seen that have such a thing will do so. However, I've always seen  
>>> it as
>>> reasonably common sense, and not worked it into the spec (though I
>>> wouldn't have a problem with making it recommended).
>> I think it makes sense to recommend it, and if so, also to mention it
>> in the spec as a special element that can exist directly within the
>> Feature object, rather than being relegated to the properties object.
> I agree with Keith. I found it a little confusing when I was
> implementing OGR driver for GeoJSON. The "id" is used in the examples
> but it isn't mentioned in the spec.

I agree that it may be confusing to have it in the examples the way  
they are. But unless there's some agreement on the semantics of an id,  
I'm not sure it makes sense to define it. Would it have to be unique?  
What about systems that don't have a concept of feature id? What if  
it's unique to the server but not to the client? etc. etc.

I like examples that show how to mix spec and non-spec things  
together, since that helps me to understand what's legal and what's  
not, but maybe the main examples should not use id.


> Greetings
> -- 
> Mateusz Loskot
> http://mateusz.loskot.net
> _______________________________________________
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> Geojson at lists.geojson.org
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Allan Doyle
Director of Technology
MIT Museum

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