将变量从数据流中的管道外部传递给ParDo

Question

如何将变量从管道外部传递给ParDo函数，然后传递给Dataflow作业。下面是一个示例，我试图在创建管道之前派生fileDate并将其传递给ParDo函数。我在接口中声明了变量

    public interface CsvToBq extends DataflowPipelineOptions {
    @Description("File Date")
    String getFileDate();

    void setFileDate(String value);
}

我将工作中的值设置为

 public static void main(String[] args) {
    PipelineOptionsFactory.register(CsvToBq.class);
    CsvToBq options = PipelineOptionsFactory
            .fromArgs(args)
            .withValidation()
            .as(CsvToBq.class);

    Date date = new Date();     
    String fileDate = formatter.format(date);
    options.setFileDate(fileDate);

并且我正在以ParDo函数的形式访问变量

 private static class WikiParDo extends DoFn<String, TableRow> {
    @ProcessElement
    public void processElement(ProcessContext c) throws Exception {

        PipelineOptions options = c.getPipelineOptions();
        String fileDate = options.getFileDate();
        String[] split = c.element().split(",");
        TableRow row = new TableRow();
        for (int i = 0; i < split.length; i++) {
            TableFieldSchema col = getTableSchema().getFields().get(i);
            row.set(col.getName(), split[i]);
        }
        row.set("file_date", fileDate);
        c.output(row);
    }
}

这里是完整的代码

public class CsvToBq {
public static void main(String[] args) {
    PipelineOptionsFactory.register(CsvToBq.class);
    CsvToBq options = PipelineOptionsFactory
            .fromArgs(args)
            .withValidation()
            .as(CsvToBq.class);

    Date date = new Date();     
    String fileDate = formatter.format(date);
    options.setFileDate(fileDate);

    Pipeline pipeline = Pipeline.create(options);
    pipeline.apply("READ", TextIO.read().from("gs://bucket/file.csv"))
            .apply("TRANSFORM", ParDo.of(new WikiParDo()))
            .apply("WRITE", BigQueryIO.writeTableRows()
                    .to(String.format("%s:dataset_name.wiki_demo", options.getProject()))
                    .withCreateDisposition(CREATE_IF_NEEDED)
                    .withWriteDisposition(WRITE_TRUNCATE)
                    .withSchema(getTableSchema()));
    pipeline.run();
}

private static TableSchema getTableSchema() {
    List<TableFieldSchema> fields = new ArrayList<>();
    fields.add(new TableFieldSchema().setName("year").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("month").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("day").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("wikimedia_project").setType("STRING"));
    fields.add(new TableFieldSchema().setName("language").setType("STRING"));
    fields.add(new TableFieldSchema().setName("title").setType("STRING"));
    fields.add(new TableFieldSchema().setName("views").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("file_date").setType("STRING"));
    return new TableSchema().setFields(fields);
}

public interface CsvToBq extends DataflowPipelineOptions {
    @Description("File Date")
    String getFileDate();

    void setFileDate(String value);
}

private static class WikiParDo extends DoFn<String, TableRow> {
    @ProcessElement
    public void processElement(ProcessContext c) throws Exception {

        PipelineOptions options = c.getPipelineOptions();
        String fileDate = options.getFileDate();

        String[] split = c.element().split(",");
        TableRow row = new TableRow();
        for (int i = 0; i < split.length; i++) {
            TableFieldSchema col = getTableSchema().getFields().get(i);
            row.set(col.getName(), split[i]);
        }
        row.set("file_date", fileDate);
        c.output(row);
    }
}

}

但是这不起作用。我尝试使用StaticValueProvider和sideinputs，但看起来不符合目的。

Answer 1

我认为您将需要以下内容：

    CsvToBq options = c.getPipelineOptions().as(CsvToBq.class);
    String fileDate = options.getFileDate();

此外，如果您不打算使用ValueProviders（a current requirement for passing parameters to Dataflow templates，则还可以执行以下操作：

private static class WikiParDo extends DoFn<String, TableRow> {
String fileName;
  public WikiParDo(String fileName) {
    this.fileName = fileName;
  }

请注意您存储的内容必须可序列化。 joda.time如果我记得的话，即时对象还可以。

Answer 2

我使用StaticValueProvider完成了此操作。有关更多信息，请参见here

我们需要定义如下扩展选项的接口

    @Description("File Date")
    ValueProvider<String[]> getFileDate();
    void setFileDate(ValueProvider<String[]> value);

在main方法中，我们可以将变量设置为

    Date date = new Date();
    String fileDate = formatter.format(date);

并且可以在管道应用转换中以]传递>

ParDo.of(new WikiParDo(StaticValueProvider.of(fileDate)))
并且在ParDo函数中，我们可以如下使用

    ValueProvider<String[]> fDate;
    StoreFrontBqConv(ValueProvider<String[]> fileDate) {
      this.fDate = fileDate;
    }

    fDate.get()
这里是完整的代码

public class CsvToBq {

public interface CsvToBq extends DataflowPipelineOptions {
    @Description("File Date")
    ValueProvider<String[]> getFileDate();
    void setFileDate(ValueProvider<String[]> value);
}

private static class WikiParDo extends DoFn<String, TableRow> {

    ValueProvider<String[]> fDate;
    StoreFrontBqConv(ValueProvider<String[]> fileDate) {
      this.fDate = fileDate;
    }

    @ProcessElement
    public void processElement(ProcessContext c) throws Exception {

        PipelineOptions options = c.getPipelineOptions();

        String[] split = c.element().split(",");
        TableRow row = new TableRow();
        for (int i = 0; i < split.length; i++) {
            TableFieldSchema col = getTableSchema().getFields().get(i);
            row.set(col.getName(), split[i]);
        }
        row.set("file_date", fDate.get());
        c.output(row);
    }
}

private static TableSchema getTableSchema() {
    List<TableFieldSchema> fields = new ArrayList<>();
    fields.add(new TableFieldSchema().setName("year").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("month").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("day").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("wikimedia_project").setType("STRING"));
    fields.add(new TableFieldSchema().setName("language").setType("STRING"));
    fields.add(new TableFieldSchema().setName("title").setType("STRING"));
    fields.add(new TableFieldSchema().setName("views").setType("INTEGER"));
    fields.add(new TableFieldSchema().setName("file_date").setType("STRING"));
    return new TableSchema().setFields(fields);
}

public static void main(String[] args) {
    PipelineOptionsFactory.register(CsvToBq.class);
    CsvToBq options = PipelineOptionsFactory.fromArgs(args).withValidation().as(CsvToBq.class);

    Date date = new Date();
    String fileDate = formatter.format(date);

    Pipeline pipeline = Pipeline.create(options);
    pipeline.apply("READ", TextIO.read().from("gs://bucket/file.csv"))
            .apply("TRANSFORM", ParDo.of(new WikiParDo(StaticValueProvider.of(fileDate)))).apply("WRITE",
                    BigQueryIO.writeTableRows().to(String.format("%s:dataset_name.wiki_demo", options.getProject()))
                            .withCreateDisposition(CREATE_IF_NEEDED).withWriteDisposition(WRITE_TRUNCATE)
                            .withSchema(getTableSchema()));
    pipeline.run();
}
}