I don't think we've considered building out Maps in Pig this way. You can of
course run your data through a UDF that would take a tuple whose first
argument is a list of key names, and invoke it like so:
jsonStore = FOREACH thing GENERATE
toMap('id foo bar', *) AS json:map[];
-D
On Thu, Nov 25, 2010 at 11:53 AM, Josh Devins <[email protected]> wrote:
> Hi all,
>
> I have a a simple schema that I want to store as JSON. So I've written a
> simple JsonStorage class but it requires that the tuple's first field is a
> map. The problem is in converting a regular tuple into a map:
>
> DESCRIBE thing;
> > thing: {id: chararray,field1: chararray,field2: chararray}
>
> What the map/JSON should look like:
> { 'id': 'id0', 'foo': 'valueFromField1', 'bar': 'valueFromField2' }
>
> So this should work but seems to be invalid syntax:
> jsonStore = FOREACH thing GENERATE
> [ 'id'#id, 'foo'#field1, 'bar'#field2 ] AS json:map[];
>
> ERROR 1000: Error during parsing. Encountered " "[" "[ "" at line 150,
> column 23.
> Was expecting one of:
> "flatten" ...
> "(" ...
> "-" ...
> "(" ...
> "(" ...
> "(" ...
> "(" ...
> "(" ...
>
> The only way I have this syntax working is if I use only constants in the
> map:
> jsonStore = FOREACH thing GENERATE
> [ 'id'#'const', 'foo'#'const', 'bar'#'const' ] AS json:map[];
>
> Is it possible to do what I'm thinking?
>
> Thanks,
>
> Josh
>
