CODEWITHSUNDEEP
springspring-boot
Patrick
Patrick

Reputation: 3981

Yaml properties as a Map in Spring Boot

We have a spring-boot project and are using application.yml files. This works exactly as described in the spring-boot documentation. spring-boot automatically looks in several locations for the files, and obeys any environment overrides we use for the location of those files.

Now we want to also expose those yaml properties as a Map. According to the documentation this can be done with YamlMapFactoryBean. However YamlMapFactoryBean wants me to specify which yaml files to use via the resources property. I want it to use the same yaml files and processing hierarchy that it used when creating properties, so that I can take still take advantage of "magical" features such as placeholder resolution in property values.

I didn't see any documentation on if this was possible. I was thinking of writing a MapFactoryBean that looked at the environment and simply reversed the "flattening" performed by the YamlProcessor when creating the properties representation of the file.

Any other ideas?

Upvotes: 2

Views: 3920

Answers (1)

Dave Syer
Dave Syer

Reputation: 58094

The ConfigFileApplicationContextListener contains the logic for searching for files in various locations. And PropertySourcesLoader loads a file (Resource) into property sources. Neither is really designed for standalone use, but you could easily duplicate them if you want more control. The PropertySourcesLoader delegates to a collection of PropertySourceLoaders so you could add one of the latter that delegates to your YamlMapFactoryBean.

A slightly awkward but workable solution would be to use the existing machinery to collect the YAML on startup. Add a new PropertySourceLoader to your META-INF/spring.factories and let it create new property sources, then post process the Environment to extract the source map(s).

Beware, though: creating a single Map from multiple YAML files, or even a single one with multiple documents (let alone multiple files with multiple documents) isn't as easy as you might think. You have a map-merge problem, and someone is going to have to define the algorithm. The flattening done in YamlMapPropertiesBean and the merge in YamlMapFactoryBean are just two choices out of (probably) a larger set of possibilities.

Upvotes: 1

Related Questions