YamlPropertiesFactoryBean has empty string returned when empty array value is present in the YAML document

This is related to #21310.

I’m using the latest spring boot version 2.2.6 and latest spring cloud config version 2.2.2.

I use GitHub as source of truth for fetching my configurations from base YAML file.

Check the property cards: [""] or just cards: [] in line number 4.

The response I get from my service for fetching the configuration is as below snapshot for a default profile API to spring cloud config server.

Please find below snapshot with response : “default.oihs.cards”: “”

Stack Overflow question: https://stackoverflow.com/questions/61096022/yamlpropertiesfactorybean-has-empty-string-returned-when-empty-array-value-is-pr

[snicoll]

Thanks for the sample. As I’ve indicated previously, the properties format has no notion of an array so you can’t expect that to be available in any shape or form in the returned Map.

Your sample is just raw checking the Map and it doesn’t demonstrate the DataType mismatch you’ve described (all values are of type String). If you need to bind this to an Array, then whatever binder you have should account for the fact that an empty String bound to an Array leads to an empty array. The Spring Boot binder does that for you so perhaps you should be using that?

I’ve added this:

@Component
@ConfigurationProperties(prefix = "test")
public class TestProperties {

	private String[] emptyArray;

	public String[] getEmptyArray() {
		return this.emptyArray;
	}

	public void setEmptyArray(String[] emptyArray) {
		this.emptyArray = emptyArray;
	}
	
}

and the following config:

test:
  emptyArray: []

and when I inject TestProperties, getEmptyArray() returns an empty array. I am going to close this now as the sample works as designed.

[snicoll]

In Spring cloud config, when propertySource is created it uses the map from yaml processor directly

That makes total sense since the goal is to output a “properties view” of the configuration. There’s nothing Spring Cloud Config should do about that.

Yes Spring binder can help in case of a POJO not in our case.

You haven’t shared what your case is in your sample so I can’t say anything about that. I think this issue has run its course in the core framework though and I hope the rationale I’ve shared explains why we’re not going to change this.