[postgis-users] How do I handle a ResultSet from a java request?

[Nicolas Ribot]

Ok, so passing a Java string back to the client should work well.


On 6 October 2015 at 16:05, Andrew Davis <drsockmonkee at gmail.com> wrote:

> I have an open layers map with a simple form that you put info into and it
> inserts into my table and then i want to show the data back with the
> results on the map via a geojson.
>
> Im working on a "full stack' demonstration of map.. database.. and server..
> On Oct 6, 2015 9:02 AM, "Nicolas Ribot" <nicolas.ribot at gmail.com> wrote:
>
>> What kind of client is plugged to your Java code ?
>> Does it expect a raw json document to process on its own, or a geographic
>> object built in Java ?
>>
>> Nicolas
>>
>> On 6 October 2015 at 15:55, Andrew Davis <drsockmonkee at gmail.com> wrote:
>>
>>> Thanks...
>>> I am just starting out on it.  I will be passing only about 40 point
>>> features first.
>>>
>>> I will make note of and go look at the stream... as well..
>>>
>>> Andy
>>> On Oct 6, 2015 8:53 AM, "Nicolas Ribot" <nicolas.ribot at gmail.com> wrote:
>>>
>>>> Hi Andy,
>>>>
>>>> Your Java ResultSet contains one big row representing your geoJson
>>>> document. You can pass it to the client by building a string from the
>>>> resultset:
>>>> String geojson = resultSet.getString(1);
>>>>
>>>> Be careful to the potential big size of the String: if you expect a big
>>>> geojson document from the database, it may be wiser to stream it to the
>>>> client from the JDBC connection instead of building a Java String.
>>>>
>>>> Nicolas
>>>>
>>>> On 6 October 2015 at 15:32, Andrew Davis <drsockmonkee at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi all..
>>>>>
>>>>> I'm sending my first question out so patience please.
>>>>>
>>>>> I've got a working servlet on my server that will query for and get
>>>>> information back from my postgis DB.
>>>>>
>>>>> Up until now I have been just parsing the results and sending back a
>>>>> json string.  I want to get a GeoJSON back from my db now.
>>>>>
>>>>> I've been working through the information I found here:
>>>>>
>>>>> http://www.postgresonline.com/journal/archives/267-Creating-GeoJSON-Feature-Collections-with-JSON-and-PostGIS-functions.html
>>>>>
>>>>> I can create the table with locations included and a geog value, and I
>>>>> can run the query below
>>>>>
>>>>> SELECT row_to_json(fc)
>>>>>  FROM ( SELECT 'FeatureCollection' As type, array_to_json(array_agg(f)) As features
>>>>>  FROM (SELECT 'Feature' As type
>>>>>     , ST_AsGeoJSON(lg.geog)::json As geometry
>>>>>     , row_to_json((loc_id, loc_name)) As properties
>>>>>    FROM locations As lg   ) As f )  As fc;
>>>>>
>>>>>
>>>>> which brings back a single line string and is in the correct format all in PGAdmin3.
>>>>>
>>>>>
>>>>> I have been trying to duplicate this from my server with java and am stuck at the point where I have
>>>>>
>>>>> run the query and have a 'thing' (ResultSet) but am unsure as to how to handle it and then pass it
>>>>>
>>>>> back to the client.
>>>>>
>>>>>
>>>>> Any help would be welcome.
>>>>>
>>>>>
>>>>> Andy..
>>>>>
>>>>>
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>>>>>
>>>>
>>>>
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