HI Doug, Thank you very much for your useful information. I used this approach in our project to support both with schema and with out schema to get the selected fields from the .avro file.
Can i update this information in the avro tool? Thanks, Saravanan On Fri, Mar 14, 2014 at 10:48 PM, Doug Cutting <[email protected]> wrote: > To generate a file with a subset of fields you can specify a 'reader' > schema that contains only the desired fields. For example, if you > have a schema like: > > {"type":"record","name":"Event","fields":[ > {"name":"id","type":"int"}, > {"name":"url","type":"string"}, > > {"name":"props","type":{"type":"array","items":{"type":"record","name":"Property","fields":[ > {"name":"key","type":"int"}, > {"name":"value","type":"string"} > ]}]} > > And you only want the ids and property values, then you can specify > the following when you create your GenericDatumReader: > > {"type":"record","name":"Event","fields":[ > {"name":"id","type":"int"}, > > {"name":"props","type":{"type":"array","items":{"type":"record","name":"Property","fields":[ > {"name":"value","type":"string"} > ]}]} > > Perhaps we should add a --schema parameter to the tojson command-line > tool that does this? > > Doug > > On Fri, Mar 14, 2014 at 1:30 AM, Saravanan Nagarajan > <[email protected]> wrote: > > HI, > > > > I successfully converted the JSON file to avro format and i cloud able > to > > see the json format using AVRO tool. > > > > But not i am trying to show only selected fields from the json file > using > > java program and i cloud able to select specific column from the SIMPLE > json > > file. > > > > In case of complex json file, i am not able to select column. > > > > For example: > > > > Assume, Employee records contain complex column with department details. > Now > > i need to generate the JSON from avro with few column from employee and > few > > column from departments. > > > > My program printed the selected column from the employee table, but not > able > > to select from department columns. I used GenericDatumReader for reading > the > > avro file. > > > > Please let me know if you have any suggestions. > > > > if you need the program, i can share separate mail. > > > > Thanks, > > Saravanan > > >
