java - 如何忽略展开字段 (CSV) 的特定子字段

Question

如何告诉 Jackson 跳过未包装的子 POJO 字段，以便当我解析为 CSV 时，它会跳过整个列？

这是一个完整的代码示例:

public class FooTest {

  class Foo {
    String something = "value";
    @JsonUnwrapped(prefix = "bar.")
    @JsonIgnoreProperties({ "toBeIgnored" })
    Bar bar;

    public String getSomething() {
      return something;
    }

    public Bar getBar() {
      return bar;
    }
  }

  class Bar {
    String toBeIgnored;

    public String getToBeIgnored() {
      return toBeIgnored;
    }
  }

  @Test
  public void fooTest() throws IOException {
    CsvMapper mapper = new CsvMapper();
    CsvSchema schema = mapper.schemaFor(Foo.class).withHeader();
    ObjectWriter csvWriter = mapper.writer(schema);
    OutputStream outputStream = new ByteArrayOutputStream();
    SequenceWriter writer = csvWriter.writeValues(outputStream);

    Foo foo = new Foo();
    foo.bar = new Bar();
    String toBeIgnored = "should not be parsed";
    foo.bar.toBeIgnored = toBeIgnored;
    writer.write(foo);
    String result = outputStream.toString();

    assertThat(result).doesNotContain(toBeIgnored);
    assertThat(result).contains("something");
    assertThat(result).doesNotContain("bar.toBeIgnored");
  }
}

请注意，我无法以任何方式修改 Bar 类。

如何在类 Foo 中指定我想要忽略 bar.toBeIgnored？

JsonIgnoreProperties 对于跳过值而不是整个列很有用。当前代码将输出一个 CSV，其中 bar.toBeIgnored 列的值为空。我只是想跳过本专栏。

Answer 1

使用:@JsonIgnoreProperties({ "toBeIgnoredA", "toBeIgnoredB"})

public class ToSerialize {
  @JsonUnwrapped(prefix = "toBeUnwrapped")
  @JsonIgnoreProperties({ "toBeIgnoredA", "toBeIgnoredB" })
  public ToBeUnwrapped toBeUnwrapped;
}

或者(很长的路要走)为 ToBeUnwrapped 创建包装类，您可以在其中自由配置 JSON 注释，而无需实际的 ToBeUnwrapped 类接触