Document that RestTemplateBuilder's rootUri only applies when String variants are used for specifying the request URL

[ryonday]

The RestTemplateBuilder documentation for the rootUri() method states:

Set a root URL that should be applied to each request that starts with '/'.

However, the following code does not result in RestTemplate expanding the URI:

 UriTemplate template = new UriTemplate("/foo?bar={bar}");


this.restTemplate = restTemplateBuilder
            .rootUri(URI.create("http://foo.bar"))
            .build();
.
.
.
URI uri = template.expand("baz");

 RequestEntity<Void> req = RequestEntity.get(uri)
                .accept(MediaType.APPLICATION_JSON)
                .header(accountLinkHeader, accountLinksHeader)
                .build();

String response = restTemplate.exchange(req, String.class);

Moreover, the exception received is EXTREMELY ambiguous when this doesn't work. In fact, the Spring exception thrown occludes the initial Apache exception (which states there's no host).

[ryonday]

Will open this against the framework.

[bclozel]

Hello @ryonday

The RestTemplateBuilder javadoc does point to RootUriTemplateHandler - all UriTemplateHandler are about expanding a String uri template + variables into a proper URI.

Because you're using a RequestEntity here, you're taking full control of the request and you're not expanding a URI template. There might be room for improvement in the RestTemplateBuilder / RootUriTemplateHandler javadoc on the Spring Boot side.

Now about the exception you're seeing, this is something indeed that should be considered in Spring Framework.

[wilkinsona]

Re-opening to consider if any improvements to our javadoc could be made.