Concept - selectors

GREYImplementation tracked in MAGNOLIA-3895@jira.GREY

Intro

• A selector is the part between the first selector delimiter and the extension of an URI. I.e. given a URI like http://myserver/mypage~x~foo=bar~.html?param=baz&param2=qux and the tilde character as the delimiter, the entire selector is ~x~foo=bar. A selector can be split in turn into several selectors separated from each other by the same delimiter.

Rationale

• Selectors existed prior to Magnolia 4.5 and they use the . (dot) char as a delimiter. As Magnolia 4.5 introduces the possibility to have the dot . character in the node names (as by JCR specification see chapter 3 paragraph 2.2 of JCR 2.0 specs) the delimiter character needs to be changed.

Delimiter

• info.magnolia.cms.core.Path has a SELECTOR_DELIMITER constant (a string) set as ~ (tilde).

Selector name-value pair

• a selector can now also be in the form name=value. I.e. given a URI http://myserver/mypage~x~foo=bar~.html foo=bar is name value selector. This kind of selector is exposed by MgnlContext.getAttribute(selectorName) and has a "local" scope (similar to HttpServletRequest scope). Thus, in the current example, MgnlContext.getAttribute("foo") will return the String "bar", whereas MgnlContext.getAttribute("foo", Context.SESSION_SCOPE) or MgnlContext.getAttribute("foo", Context.APPLICATION_SCOPE) will return null.

AggregationState

• this class exposes some methods to set and get selectors.
  • setSelector(String selector) is currently used by info.magnolia.cms.filters.RepositoryMappingFilter where the request URI is parsed and the selector part extracted.
  • String getSelector() returns the whole selector. I.e given the URI http://myserver/mypage~x~foo=bar~.html this method will return the String x~foo=bar
  • String[] getSelectors() returns the selector split into its discrete elements. I.e given the URI http://myserver/mypage~x~foo=bar~.html this method will return an array of two elements containing the "x" and the "foo=bar" String(s)

SelectorUtil

• this is a utility class already existing before Magnolia 4.5. It provides two methods which are basically shortcuts to the getters in AggregationState:
  • String getSelector()
  • String getSelector(int index)