Hi Roman,

This approach works for java.sql.Timestamp, which was another type for 
which a JSON writer wasn't defined in my case.

For org.postgresql.jdbc4.Jdbc4Array however, there's something missing, 
because I get:

    *org.postgresql.util.PSQLException: This connection has been closed.*

As the person answering me on Stack Overflow suggested, it seems that the 
resultset should be somehow processed before the connection is closed, but 
I really don't know how to do given the construct I'm currently using:

(json/write-str
  (jdbc/query *db*
    ["SELECT * FROM .."]))

where and how could I intercept the resultset that way? Thanks.



On Tuesday, October 1, 2013 12:49:10 PM UTC-4, r0man wrote:
>
> I think you need to implement the JSONWriter protocol for the
> Jdbc4Array class, and possibly for the datatypes that are in the
> array. This for example makes the json library aware of
> java.util.Date classes. 
>
> (extend-type java.util.Date
>   JSONWriter
>   (-write [date out]
>     (-write (str date) out)))
>
> Something like this (not tested):
>
> (extend-type org.postgresql.jdbc4.Jdbc4Array
>   JSONWriter
>   (-write [array out]
>     (-write (seq (.getArray array)) out)))
>
> Roman
>
>
> On Tuesday, October 1, 2013 3:57:02 PM UTC+2, Christian Jauvin wrote:
>>
>> Hi,
>>
>> I asked this question on Stack Overflow yesterday:
>>
>> I want to jsonify the results of a query performed against a Postgres 
>> table containing a column of type text[], but the problem is that 
>> clojure.data.json.write-str doesn't seem to know how to handle PG arrays:
>>
>> *Exception Don't know how to write JSON of class 
>> org.postgresql.jdbc4.Jdbc4Array  clojure.data.json/write-generic*
>>
>> Do I have to supply a custom handler, or is there a simpler way?
>>
>>
>>
>> http://stackoverflow.com/questions/19103870/jsonify-a-jdbc4array-in-clojure
>>
>> I'm asking it here in the hope of getting (maybe) a simpler solution, or 
>> at least one I can implement readily, because the problem I have with one 
>> of the suggestions I received (extending org.postgresql.jdbc4.Jdbc4Arrayto 
>> implement the missing function) is that I don't know how to make it work 
>> with my usage pattern, which is simply:
>>
>> (json/write-str 
>>     (jdbc/query *db* 
>>         ["SELECT * FROM ..."]))
>>
>> How do I "get the array before the connection is closed" with such a 
>> construct? Is there another way?
>>
>>

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