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Pig >> mail # user >> Parse Nested JSON String in Pig


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Dan Zhu 2013-07-24, 21:12
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Re: Parse Nested JSON String in Pig
There is a missing dependency, a jar with class
com.fasterxml.jackson.databind.ObjectMapper
Use Google to find jar. Suggest you to use maven public repos.
24.07.2013 23:16 пользователь "Dan Zhu" <[EMAIL PROTECTED]> написал:

> Hi pig-users,
>
> I have tuples of nested JSON string, I am trying to parse it in Pig.
>
> I tried com.twitter.elephantbird.pig.piggybank.JsonStringToMap()
> (acctDataJsonized = FOREACH acctData GENERATE
> com.mozilla.pig.eval.json.JsonMap($0) AS json_map:map[];) but it only
> parsed the first level rather than nested.
>
> I also tried com.mozilla.pig.eval.json.JsonMap() (acctDataJsonized > FOREACH acctData GENERATE
> com.twitter.elephantbird.pig.piggybank.JsonStringToMap($0);) but it throws:
> (is it due to NULL value in the JSON data?)
>
> ERROR 1200: Pig script failed to parse:
> <line 7, column 45> Failed to generate logical plan. Nested exception:
> java.lang.RuntimeException: could not instantiate
> 'com.mozilla.pig.eval.json.JsonMap' with arguments 'null'
>
> Failed to parse: Pig script failed to parse:
> <line 7, column 45> Failed to generate logical plan. Nested exception:
> java.lang.RuntimeException: could not instantiate
> 'com.mozilla.pig.eval.json.JsonMap' with arguments 'null'
> at
> org.apache.pig.parser.QueryParserDriver.parse(QueryParserDriver.java:184)
> at org.apache.pig.PigServer$Graph.validateQuery(PigServer.java:1570)
> at org.apache.pig.PigServer$Graph.registerQuery(PigServer.java:1543)
> at org.apache.pig.PigServer.registerQuery(PigServer.java:545)
> at org.apache.pig.tools.grunt.GruntParser.processPig(GruntParser.java:970)
> at
> org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:386)
> at
> org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:189)
> at
> org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:165)
> at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:69)
> at org.apache.pig.Main.run(Main.java:495)
> at org.apache.pig.Main.main(Main.java:111)
> Caused by:
> <line 7, column 45> Failed to generate logical plan. Nested exception:
> java.lang.RuntimeException: could not instantiate
> 'com.mozilla.pig.eval.json.JsonMap' with arguments 'null'
> at
> org.apache.pig.parser.LogicalPlanBuilder.buildUDF(LogicalPlanBuilder.java:980)
> at
> org.apache.pig.parser.LogicalPlanGenerator.func_eval(LogicalPlanGenerator.java:7316)
> at
> org.apache.pig.parser.LogicalPlanGenerator.projectable_expr(LogicalPlanGenerator.java:8857)
> at
> org.apache.pig.parser.LogicalPlanGenerator.var_expr(LogicalPlanGenerator.java:8632)
> at
> org.apache.pig.parser.LogicalPlanGenerator.expr(LogicalPlanGenerator.java:7984)
> at
> org.apache.pig.parser.LogicalPlanGenerator.flatten_generated_item(LogicalPlanGenerator.java:5962)
> at
> org.apache.pig.parser.LogicalPlanGenerator.generate_clause(LogicalPlanGenerator.java:14101)
> at
> org.apache.pig.parser.LogicalPlanGenerator.foreach_plan(LogicalPlanGenerator.java:12493)
> at
> org.apache.pig.parser.LogicalPlanGenerator.foreach_clause(LogicalPlanGenerator.java:12360)
> at
> org.apache.pig.parser.LogicalPlanGenerator.op_clause(LogicalPlanGenerator.java:1577)
> at
> org.apache.pig.parser.LogicalPlanGenerator.general_statement(LogicalPlanGenerator.java:789)
> at
> org.apache.pig.parser.LogicalPlanGenerator.statement(LogicalPlanGenerator.java:507)
> at
> org.apache.pig.parser.LogicalPlanGenerator.query(LogicalPlanGenerator.java:382)
> at
> org.apache.pig.parser.QueryParserDriver.parse(QueryParserDriver.java:177)
> ... 10 more
> Caused by: java.lang.RuntimeException: could not instantiate
> 'com.mozilla.pig.eval.json.JsonMap' with arguments 'null'
> at
> org.apache.pig.impl.PigContext.instantiateFuncFromSpec(PigContext.java:554)
> at
> org.apache.pig.impl.PigContext.instantiateFuncFromSpec(PigContext.java:560)
> at
> org.apache.pig.impl.PigContext.instantiateFuncFromAlias(PigContext.java:583)
> at
> org.apache.pig.parser.LogicalPlanBuilder.buildUDF(LogicalPlanBuilder.java:977)
> ... 23 more
> Caused by: java.lang.NoClassDefFoundError: Could not initialize class
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Harsha 2013-07-24, 21:27