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From Jihoon Son <ghoon...@gmail.com>
Subject Re: A couple of questions about JSON query support
Date Fri, 14 Nov 2014 08:15:15 GMT
The code lines where you made the above changes are in Expr.JsonSerder
which is no longer used.
Every class extended from Expr has a function of toJson() which is
inherited from Expr. This function uses JsonHelper to generate json
strings.
In JsonHelper, you can find several adapters like OpType.JsonSerder.
You may modify this class instead of Expr.JsonSerder.

I hope this will be helpful for you.
Jihoon

2014-11-14 16:52 GMT+09:00 Jaewoong Jung <jungjw@gmail.com>:

> On Thu, Nov 13, 2014 at 11:39 PM, Jihoon Son <ghoonson@gmail.com> wrote:
> > Hi Jaewoong,
> > thanks for your interest.
> > Here are my answers.
> >
> > 1. You are right. We should make TajoCli support only SQL, and create a
> new
> > client for JSON.
> > 2. Can you tell me what kinds of changes you made? In most cases, you can
> > see the effect of your changes immediately, except when you modify the
> > protocol buffers codes.
>
> It was a really simple change like this.
>
> * From
> 127:      String opType =
> jsonObject.get(SERIALIZED_NAME_OF_OP_TYPE).getAsString();
>
> * To
> 127:      JsonElement opTypeElement =
> jsonObject.get(SERIALIZED_NAME_OF_OP_TYPE);
> 128:      if (opTypeElement == null) {
> 129:        throw new JsonParseException("Missing required field: " +
> SERIALIZED_NAME_OF_OP_TYPE);
> 130:      }
> 131:      String opType = opTypeElement.getAsString();
>
> FYI, I was trying to fix a bug where tsql just shows a dumb error
> message, "ERROR: java.lang.NullPointerException" when an OpType field
> is missing.
>
> No matter how I change the code, it throws a NullPointerException from
> the same line of the code. I even tried adding a few blank lines above
> 127, but the error trace shows that a NullPointerException was thrown
> from the same line all the time.
>
> Strangely enough, if I make a typo to see whether my change gets
> compiled, mvn stops with a proper error message. :(
>
> >
> > Thanks,
> > Jihoon
> >
> > 2014-11-14 16:13 GMT+09:00 Jaewoong Jung <jungjw@gmail.com>:
> >
> >> 1. I found this issue (https://issues.apache.org/jira/browse/TAJO-826)
> >> which has a comment that we should remove all JSON related part from
> >> TajoCli. Does it mean that we want to make tsql support SQL queries
> >> only and create a separate client dedicated for JSON queries?
> >>
> >> 2. While trying to fix a minor bug in JSON parsing, I found that any
> >> of changes I made to Expr.java had no effect on tsql behavior. Does it
> >> read a pre-compiled jar file from somewhere else? What should I do to
> >> test my Expr changes?
> >>
> >> Thanks,
> >> Jaewoong
> >>
> >
> >
> >
> > --
> > Jihoon Son
> >
> > Database & Information Systems Group,
> > Prof. Yon Dohn Chung Lab.
> > Dept. of Computer Science & Engineering,
> > Korea University
> > 1, 5-ga, Anam-dong, Seongbuk-gu,
> > Seoul, 136-713, Republic of Korea
> >
> > Tel : +82-2-3290-3580
> > E-mail : jihoonson@korea.ac.kr
>



-- 
Jihoon Son

Database & Information Systems Group,
Prof. Yon Dohn Chung Lab.
Dept. of Computer Science & Engineering,
Korea University
1, 5-ga, Anam-dong, Seongbuk-gu,
Seoul, 136-713, Republic of Korea

Tel : +82-2-3290-3580
E-mail : jihoonson@korea.ac.kr

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