public ReadResult expand()

in java/java-dataflow-samples/read-pubsub-write-bigquery/src/main/java/com/cloudcode/dataflow/example/io/ReadPubsubToRow.java [45:63]

• 10 lines of code
• 1 McCabe index (conditional complexity)

  public ReadResult expand(PBegin input) {
    // We implement this PTransform in two main steps.  First, we read Pub/Sub JSON encoded
    // string messages.
    PCollection<String> json =
        input.apply(
            "Read Json Messages", PubsubIO.readStrings().fromSubscription(subscription.getPath()));

    // Next, we apply the JsonToRow PTransform to convert JSON strings to Beam Rows.
    PCollectionTuple toRowResult = json.apply("To Row", JsonToRow.of(userType));

    // Finally, we bundle our errors and expected results into a ReadResult convenience class.
    PCollection<String> errors = toRowResult.get(ERROR);
    PCollection<Row> rows = toRowResult.get(ROW);
    return ReadResult.of(
        // ***IMPORTANT: Notice the rows.setRowSchema(rows.getSchema()) semantic. This
        // avoids errors at pipeline construction time when it complains that it cannot
        // derive your Schema.***
        input.getPipeline(), ROW, rows.setRowSchema(rows.getSchema()), ERROR, errors);
  }