Interface MetaDataLocator

  • 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 via ComponentModel.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, then SymbolSource.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.
    • Method Detail

      • findMeta

        <T> T findMeta​(String key,
                       ComponentResources resources,
                       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:
        RuntimeException - if the value for the key is not present as meta data of the component, as an override, or as a symbol
      • findMeta

        <T> T findMeta​(String key,
                       String pageName,
                       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:
        RuntimeException - if the value for the key is not present as meta data of the page, as an override, or as a symbol