Package org.apache.tapestry5.services
Interface MetaDataLocator
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- All Known Implementing Classes:
MetaDataLocatorImpl
@UsesMappedConfiguration(java.lang.String.class) public interface MetaDataLocator
Used to lookup meta data concerning a particular component. The primary source of meta data is the meta data defined for the component, accessed viaComponentModel.getMeta(String)
. This includes meta data defined by base classes. When meta-data for a particular component can not be found, a search works up the containment hierarchy (to the component's container, and the container's container, and so on). If that proves unfruitful, a system of defaults is provided by configuration and matched against the containing page's logical name. Finally, if no metadata is available, thenSymbolSource.valueForSymbol(String)
is used to obtain a value. Generally speaking, if you are going to use this service to look up meta data, your should also make a contribution to the FactoryDefaults service; otherwise, you risk a runtime exception if a meta-data key can not be resolved.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description <T> T
findMeta(java.lang.String key, java.lang.String pageName, java.lang.Class<T> expectedType)
Searches for the value for the corresponding key for a particular page name (the page will not be loaded).<T> T
findMeta(java.lang.String key, ComponentResources resources, java.lang.Class<T> expectedType)
Searches for the value for the corresponding key.
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Method Detail
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findMeta
<T> T findMeta(java.lang.String key, ComponentResources resources, java.lang.Class<T> expectedType)
Searches for the value for the corresponding key. The value, if located, will have symbols expanded, and will be type coerced to the desired type.- Parameters:
key
- the key used to locate the meta data (case insensitive)resources
- the resources of the initial component used in the search- Returns:
- the value if found (in the component, the component's container, etc. or via a folder default)
- Throws:
java.lang.RuntimeException
- if the value for the key is not present as meta data of the component, as an override, or as a symbol
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findMeta
<T> T findMeta(java.lang.String key, java.lang.String pageName, java.lang.Class<T> expectedType)
Searches for the value for the corresponding key for a particular page name (the page will not be loaded). The value, if located, will have symbols expanded, and will be type coerced to the desired type.- Parameters:
key
- the key used to locate the meta data (case insensitive)pageName
- the name of the page to search- Returns:
- the value if found
- Throws:
java.lang.RuntimeException
- if the value for the key is not present as meta data of the page, as an override, or as a symbol
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