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From "Andrea Pierleoni (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (BEAM-2595) WriteToBigQuery does not work with nested json schema
Date Wed, 12 Jul 2017 00:06:00 GMT

     [ https://issues.apache.org/jira/browse/BEAM-2595?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Andrea Pierleoni updated BEAM-2595:
-----------------------------------
    Description: 
I am trying to use the new `WriteToBigQuery` PTransform added to `apache_beam.io.gcp.bigquery`
in version 2.1.0-RC1

I need to write to a bigquery table with nested fields.
The only way to specify nested schemas in bigquery is with teh json schema.
None of the classes in `apache_beam.io.gcp.bigquery` are able to parse the json schema, but
they accept a schema as an instance of the class `apache_beam.io.gcp.internal.clients.bigquery.TableFieldSchema`

I am composing the `TableFieldSchema` as suggested here [https://stackoverflow.com/questions/36127537/json-table-schema-to-bigquery-tableschema-for-bigquerysink/45039436#45039436],
and it looks fine when passed to the PTransform `WriteToBigQuery`. 

The problem is that the base class `PTransformWithSideInputs` try to pickle and unpickle the
function [https://github.com/apache/beam/blob/master/sdks/python/apache_beam/transforms/ptransform.py#L515]
 (that includes the TableFieldSchema instance) and for some reason when the class is unpickled
some `FieldList` instance are converted to simple lists, and the pickling validation fails.

Would it be possible to extend the test coverage to nested json objects for bigquery?
They are also relatively easy to parse into a TableFieldSchema.


  was:
I am trying to use the new `WriteToBigQuery` PTransform added to `apache_beam.io.gcp.bigquery`
in version 2.1.0-RC1

I need to write to a bigquery table with nested fields.
The only way to specify nested schemas in bigquery is with teh json schema.
None of the classes in `apache_beam.io.gcp.bigquery` are able to parse the json schema, but
they accept a schema as an instance of the class `apache_beam.io.gcp.internal.clients.bigquery.TableFieldSchema`

I am composing the `TableFieldSchema` as suggested [here](https://stackoverflow.com/questions/36127537/json-table-schema-to-bigquery-tableschema-for-bigquerysink/45039436#45039436),
and it looks fine when passed to the PTransform `WriteToBigQuery`. 

The problem is that the base class `PTransformWithSideInputs` try to [pickle and unpickle
the function](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/transforms/ptransform.py#L515)
 (that includes the TableFieldSchema instance) and for some reason when the class is unpickled
some `FieldList` instance are converted to simple lists, and the pickling validation fails.

Would it be possible to extend the test coverage to nested json objects for bigquery?
They are also relatively easy to parse into a TableFieldSchema.



> WriteToBigQuery does not work with nested json schema
> -----------------------------------------------------
>
>                 Key: BEAM-2595
>                 URL: https://issues.apache.org/jira/browse/BEAM-2595
>             Project: Beam
>          Issue Type: Bug
>          Components: runner-dataflow
>    Affects Versions: 2.1.0
>         Environment: mac os local runner, Python
>            Reporter: Andrea Pierleoni
>            Assignee: Thomas Groh
>            Priority: Minor
>              Labels: gcp
>
> I am trying to use the new `WriteToBigQuery` PTransform added to `apache_beam.io.gcp.bigquery`
in version 2.1.0-RC1
> I need to write to a bigquery table with nested fields.
> The only way to specify nested schemas in bigquery is with teh json schema.
> None of the classes in `apache_beam.io.gcp.bigquery` are able to parse the json schema,
but they accept a schema as an instance of the class `apache_beam.io.gcp.internal.clients.bigquery.TableFieldSchema`
> I am composing the `TableFieldSchema` as suggested here [https://stackoverflow.com/questions/36127537/json-table-schema-to-bigquery-tableschema-for-bigquerysink/45039436#45039436],
and it looks fine when passed to the PTransform `WriteToBigQuery`. 
> The problem is that the base class `PTransformWithSideInputs` try to pickle and unpickle
the function [https://github.com/apache/beam/blob/master/sdks/python/apache_beam/transforms/ptransform.py#L515]
 (that includes the TableFieldSchema instance) and for some reason when the class is unpickled
some `FieldList` instance are converted to simple lists, and the pickling validation fails.
> Would it be possible to extend the test coverage to nested json objects for bigquery?
> They are also relatively easy to parse into a TableFieldSchema.



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