Multiple Locations

[smilehappy126]

Hello,

I try to connect several Locations to one Thing through HTTP, however, the second location keep overwrite the first one and make this Thing's Location remain one location.

Did anyone occur same problem or solve it?

Any help will be appreciated. Thanks a lot.

[hylkevds]

A Thing can only have 1 real-world location. Therefore, if you add a new Location to a Thing, the old location is automatically removed.
A Thing can have multiple Location entities, but they have to be different encodings of the same real-world location.
To link these multiple Location entities to the Thing, you have to link them all in the same request.

[smilehappy126]

Hi,
Thanks for replying. I've tried create new Things through Postman and link to two existed location as below.

However, I'd like to create Thing and also create two new Locations link it at the same times. I'd try to POST like this:

But the "test2" Location just automatically overwrite "test1" Location.
Am I missing something?

Thanks for any advices!

[hylkevds]

Your test2 JSON is not valid.
A JSON object is a set of key-value pairs, and each key is only allowed to exist once. Your test2 JSON has the key "Locations" twice, and thus only one of the two is ever available.

[smilehappy126]

Hi,
Successfully create. However, it seems to be considered as one Location with two kinds of descriptions.
How can I create two different Locations Object just in one request.

Thanks for answering.

[hylkevds]

That JSON looks fine to me. Locations is an array, with two objects in it.
If you format your JSON properly it'll be easier to recognise.

[smilehappy126]

Thanks a lot. The problem is fixed.

[smilehappy126]

Hi,
Now with the Multiple Location, it seems that Observation can't automatically link Location as it's FeatureOfInterest.
How can I let the server automatically use the first Location object in Location Array as the Observation's FeatureOfInterest?

Thanks for answering.

[hylkevds]

Hmm, it seems it fetches the first Location it finds in the database. If that happens to be one of the non-geoJSON Locations, it'll fail. Which error message do you get?

[smilehappy126]

This is how the Locations Table looks like in my PostgreSQL:

And the error code was "HTTP code 500", using Eclipse :

[hylkevds]

Ok, that's the client side error, do you happen to have the server-side exception from the server logs?

[hylkevds]

It should work in the master branch now.

[smilehappy126]

Thanks for fixed it, the problem of FeatureOfInterest was solved.
However, there's something bad happened.

As the pic shows, the Location which was selected to be Observation's FeatureOfInterest disappeared in the /v1.0/Location, but it still remain in postgre's Location Table.

[hylkevds]

Can you add an orderby to that query, to make sure it isn't somewhere else in the result set? Without an explicit orderby you never know which oder PostgreSQL gives you the results.

[smilehappy126]

Oh, I found it when I orderby "@iot.id". Thanks a lot !!