Path variable values missing in RedirectView when PathPattern are used

[NobleMathews]

Affects: 6.1.2+ (probably since the introduction of PathPatterns)

---

When you use a RedirectView with an URI that contains a path variable, and PathPatterns are enabled, then the variable value is missing.

This is due to the fact that the PathPattern [codepath of]( AbstractUrlHandlerMapping is calling [buildPathExposingHandler() with uriTemplateVariables parameter of null](

As a consequence no PathExposingHandlerInterceptor is added to the execution chain. The variable values are never parsed from the URI.

When RedirectView tries to access the variable values of the variables in the URI at [replaceUriTemplateVariables() it throws an IllegalArgumentException](

When AntPatterns are used instead of PathPatterns, then the variable values are parsed and all is well.

public class TestMvConfiguration implements WebMvcConfigurer {

    public void addViewControllers(ViewControllerRegistry registry) {
        String srcPath = "/some/path/{variable}/foo"; 
        String tgtPath = "/some/path/{variable}/bar";
        registry.addRedirectViewController(srcPath, tgtPath)
                .setStatusCode(HttpStatus.PERMANENT_REDIRECT);
    }

    public void configurePathMatch(PathMatchConfigurer configurer) {
        configurer.setPatternParser(new PathPatternParser());  // broken
//       configurer.setPathMatcher(new AntPathMatcher());      // works
    }

}

[mayil-ai[bot]]

Here are some code snippets that may help you get started:

• spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractUrlHandlerMapping.java:46-579 | This snippet includes the implementation of UriTemplateVariablesHandlerInterceptor, which is crucial for exposing URI template variables, addressing the IllegalArgumentException issue with RedirectView.

• spring-webmvc/src/main/java/org/springframework/web/servlet/view/RedirectView.java:359-684 | This snippet contains the replaceUriTemplateVariables method, which is essential for handling URI template variables in RedirectView, directly related to the IllegalArgumentException issue.

To address the issue with RedirectView failing to access path variable values when using PathPattern, follow these steps:

• Modify AbstractUrlHandlerMapping: Ensure uriTemplateVariables are correctly populated and passed to buildPathExposingHandler().

  String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
  if (getPathMatcher().match(pattern, lookupPath)) {
    Map<String, String> uriTemplateVariables = getPathMatcher().extractUriTemplateVariables(pattern, lookupPath);
    exposeUriTemplateVariables(uriTemplateVariables, request);
    return new RequestMatchResult(pattern, lookupPath, getPathMatcher());
  }
  // Handle trailing slash match similarly
  return null;

• Add UriTemplateVariablesHandlerInterceptor: Ensure it is added to the handler chain when PathPattern is used.

  protected Object buildPathExposingHandler(Object handler, String bestMatchingPattern, String pathWithinMapping, Map<String, String> uriTemplateVariables) {
    if (uriTemplateVariables != null) {
        return new UriTemplateVariablesHandlerInterceptor(uriTemplateVariables);
    }
    return handler;
  }

• Verify RedirectView Access: This setup ensures that RedirectView can access the path variables correctly, preventing IllegalArgumentException.

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