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Document differences between @Value and @ConfigurationProperties 

Closes gh-4892
This commit is contained in:
Stephane Nicoll 2016-07-11 12:23:30 +02:00
parent a72e494896
commit 277da462ce
1 changed files with 39 additions and 2 deletions
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41
spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc
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@ -734,8 +734,8 @@ Nested POJO properties can also be created (so a setter is not mandatory) if the
default constructor, or a constructor accepting a single value that can be coerced from
String. Some people use Project Lombok to add getters and setters automatically.
NOTE: Contrary to `@Value`, SpEL expressions are not evaluated prior to injecting a value
in the relevant `@ConfigurationProperties` bean.
TIP: See also the <<boot-features-external-config-vs-value,differences between `@Value`
and `@ConfigurationProperties`>>.
The `@EnableConfigurationProperties` annotation is automatically applied to your project
so that any beans annotated with `@ConfigurationProperties` will be configured from the
@ -954,6 +954,43 @@ _<<production-ready-features.adoc#production-ready-endpoints, Production ready f
section for details.
[[boot-features-external-config-vs-value]]
==== @ConfigurationProperties vs. @Value
`@Value` is a core container feature and it does not provide the same features as type-safe
Configuration Properties. The table below summarizes the features that are supported by
`@ConfigurationProperties` and `@Value`:
[cols="4,2,2"]
|===
|Feature |`@ConfigurationProperties` |`@Value`
| <<boot-features-external-config-relaxed-binding,Relaxed binding>>
| Yes
| No
| <<appendix-configuration-metadata.adoc#configuration-metadata,Meta-data support>>
| Yes
| No
| `SpEL` evaluation
| No
| Yes
|===
If you define a set of configuration keys for your own components, we recommend you to
group them in a pojo annotated with `@ConfigurationProperties`. Please also be aware
that since `@Value` does not support relaxed binding, it isn't a great candidate if you
need to provide the value using environment variables.
Finally, while you can write a `SpEL` expression in `@Value`, such expressions are not
processed from <<boot-features-external-config-application-property-files,Application
property files>>.
[[boot-features-profiles]]
== Profiles
Spring Profiles provide a way to segregate parts of your application configuration and