> For the complete documentation index, see [llms.txt](https://jack80342.gitbook.io/spring-boot/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jack80342.gitbook.io/spring-boot/x.-appendices/b.-configuration-metadata/b.2-providing-manual-hints/b.2.1-value-hint.md).

# 附录 B.2.1 值提示

每一个hint的`name`属性参考了property的`name`。在[上面最初的例子](https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#configuration-metadata-format)里，我们为`spring.jpa.hibernate.ddl-auto`属性提供了5个值：`none`、`validate`、`update`、`create`和`create-drop`。每个值也可以有一个描述。

如果你的属性不是`Map`类型，你可以为key和value一起提供hint（但不是为map它自己）。特殊的`.keys`和`.values`后缀必须被分别地用于参考keys和values。

让我们假设一个`sample.contexts`，它把神奇的String值映射到一个Integer：

```java
@ConfigurationProperties("sample")
public class SampleProperties {

    private Map<String,Integer> contexts;
    // getters and setters
}
```

例如，神奇的值是`sample1`和`sample2`。为了给key提供额外的内容帮助，你可以将以下内容添加到[模块的手工元数据](https://docs.spring.io/spring-boot/docs/2.0.0.RELEASE/reference/htmlsingle/#configuration-metadata-additional-metadata)：

```javascript
{"hints": [
    {
        "name": "sample.contexts.keys",
        "values": [
            {
                "value": "sample1"
            },
            {
                "value": "sample2"
            }
        ]
    }
]}
```

**注** 我们建议你对这两个值使用`Enum`。如果你的IDE支持，这是目前为止实现自动补全的最有效的方式。


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