Unable to serialize objects using desired YAML formatting style

[bhreinb]

Hi there,

This is either a question or minor issue (apologies if it's the former). I'm serializing a pojo using the below code logic

public static <T> String SerializeToRawYaml(final T yamlT) {        
       final ObjectMapper mapper = new ObjectMapper(new YAMLFactory()
                .configure(YAMLGenerator.Feature.WRITE_DOC_START_MARKER, false)
        )
                .enable(SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED);
        mapper.setVisibility(mapper.getSerializationConfig().getDefaultVisibilityChecker()
                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE)
                .withIsGetterVisibility(JsonAutoDetect.Visibility.NONE));
        try {
            return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(yamlT);
        }
        catch (JsonProcessingException e) {
            System.out.println(
                    String.format("Problem Serializing POJO Because Of Error %s", e)
            );
        }
    }

This produces sample yaml like so

name: "OuterYamlElementName"
label: "OuterYamlElementLabel"
fields:
  label: "outerYamlFieldLabel"
  value: "outerYamlFieldValue"
  isRequired: true
  toggle: "+BEYWAYS-Outer-Yaml-Field"
elements:
  name: "InnerYamlElementDepthOneName"
  label: "InnerYamlElementDepthOneLabel"
  fields:
  - label: "innerYamlFieldsDepthOneItemOneLabel"
    value: "innerYamlFieldsDepthOneItemOneValue"
    isRequired: true
    toggle: "-BEYWAYS-Inner-Yaml-Fields-Depth-One-Item-One"
  - label: "innerYamlFieldsDepthOneItemTwoLabel"
    value: "innerYamlFieldsDepthOneItemTwoValue"
    isRequired: false
  toggle: "-BEYWAYS-Inner-Yaml-Element-Depth-One"
toggle: "+BEYWAYS-Outer-Yaml-Element"

however I'd like the yaml to be generated like so

name: "OuterYamlElementName"
label: "OuterYamlElementLabel"
fields:
  - {label: "outerYamlFieldLabel", value: "outerYamlFieldValue", isRequired: true, toggle: "+BEYWAYS-Outer-Yaml-Field"}
elements:
  name: "InnerYamlElementDepthOneName"
  label: "InnerYamlElementDepthOneLabel"
  fields:
    - { label: "innerYamlFieldsDepthOneItemOneLabel", value: "innerYamlFieldsDepthOneItemOneValue", isRequired: true, toggle: "-BEYWAYS-Inner-Yaml-Fields-Depth-One-Item-One" }
    - { label: "innerYamlFieldsDepthOneItemTwoLabel", value: "innerYamlFieldsDepthOneItemTwoValue", isRequired: false }
  toggle: "-BEYWAYS-Inner-Yaml-Element-Depth-One"
toggle: "+BEYWAYS-Outer-Yaml-Element"

namely the fields items are condensed into bracket format. Is that currently supported and if so what do I need to do in order to generate that output. Thanks in advance.

[cowtowncoder]

@bhreinb Usage questions are often better for mailing lists:

https://groups.google.com/forum/#!forum/jackson-user

or chat

https://gitter.im/FasterXML/jackson-databind

but have you tried using YAMLGenerator.Feature settings? If SnakeYAML (underlying encoder/decoder) supports combinations, it could be technically possible.

But since this is pretty low-level tinkering, and is something not relevant to Jackson API modeled after needs of JSON handling, I do not think this is currently supported.
If there is a way to define in compact way a kind of "yes / no" rule, it could be added as a new YAMLGenerator.Feature, among existing ones. But might get trick wrt combinations.

Or, for bigger question on changing output style...
If someone comes up with a way to expose YAML-specific "pretty-printing" configuration -- tough part being API to use, can not use PrettyPrinter that exists -- it could be an improvement.

[bhreinb]

Hi @cowtowncoder

Thanks for your response. Apologies for not posting the question there in the first place, I didn't know of those mailer lists so I will ask there first in future.

I'm already using YAMLGenerator.Feature (see snippet)

final ObjectMapper mapper = new ObjectMapper(new YAMLFactory()
                .configure(YAMLGenerator.Feature.WRITE_DOC_START_MARKER, false)

and I tried all the combinations available unfortunately to no avail. Perhaps this is an improvement so assuming SnakeYAML supports this?

[cowtowncoder]

Yes, I suspect SnakeYAML could produce such formatting. One thing that could help someone implement this (I doubt I will have time to work on this any time soon, unfortunately) could be to show settings with SnakeYAML API to generate content. I know it supports different styles.

[bhreinb]

I will have a look at to what the settings are within SnakeYAML and report my findings. There is two items here

1. indent lines that start with -
2. generate output in object format