Spring Spring deserialize YAML as LinkedHashMap instead of ArrayList

I report the bug present in Spring deserialize YAML as LinkedHashMap instead of ArrayList because I ran into the same problem. I tried to update to SpringBoot 2.7.9 but issue persists. My case is reading YAML file and assign value to Map<String, Object>, but as in the eample present in StackOverflow, Spring map to LinkedHashMap instead of ArrayList. I use Java 17.

Comment From: simonbasle

Spring Framework has limited integration for YAML, supporting SnakeYAML as a deserialization library through YamlProcessor, YamlPropertiesBeanFactory and YamlMapBeanFactory classes. However, there's no automated support for YAML. You have to manually configure and use the aforementioned classes.

Also, in order to support the historical primary use case of YAML from the Framework's perspective, these classes further process the deserialized YAML data structure. Most notably, when deserializing to a Properties the processing seeks a flat representation of leaves in the YAML structure, with String values and flattened String keys. Dictionaries entries are turned into dot-separated "paths" and arrays entries are turned into [x] indexed keys.

Note that the deserialized Map available to YamlProcessor.MatchCallback#process(Properties, Map) is the closest you can get to the SnakeYAML-returned structure, although some keys are sanitized / processed. That map is what gets exposed by YamlMapFactoryBean btw.

Note also that SnakeYAML does appear to deserialize this kind of YAML into a List of Maps:

listOfMaps:
  - name: first
    position: 1
  - name: second
    position: 2

So you might want to consider one of the following alternatives: - use YamlMapFactoryBean to load the YAML content - roll your own YamlProcessor to load the YAML content - roll your own deserialization using either SnakeYAML directly, or another deserialization library