URI Path Variables

URI variables can be referenced via method arguments. For example:

URI Variables Example

import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;
import io.micronaut.http.annotation.PathVariable;
@Controller("/issues") (1)
public class IssuesController {
    @Get("/{number}") (2)
    public String issue(@PathVariable Integer number) { (3)
        return "Issue # " + number + "!"; (4)
    }
}

URI Variables Example

import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import io.micronaut.http.annotation.PathVariable
@Controller("/issues") (1)
class IssuesController {
    @Get("/{number}") (2)
    String issue(@PathVariable Integer number) { (3)
        "Issue # " + number + "!" (4)
    }
}

URI Variables Example

import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import io.micronaut.http.annotation.PathVariable
@Controller("/issues") (1)
class IssuesController {
    @Get("/{number}") (2)
    fun issue(@PathVariable number: Int): String { (3)
        return "Issue # $number!" (4)
    }
}

Micronaut will map the URI /issues/{number} for the above controller. We can assert this is the case by writing a set of unit tests:

Testing URI Variables

import io.micronaut.context.ApplicationContext;
import io.micronaut.http.client.HttpClient;
import io.micronaut.http.client.exceptions.HttpClientResponseException;
import io.micronaut.runtime.server.EmbeddedServer;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.jupiter.api.Assertions;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
public class IssuesControllerTest {
    private static EmbeddedServer server;
    private static HttpClient client;
    @BeforeClass (1)
    public static void setupServer() {
        server = ApplicationContext.run(EmbeddedServer.class);
        client = server
                    .getApplicationContext()
                    .createBean(HttpClient.class, server.getURL());
    }
    @AfterClass (2)
    public static void stopServer() {
        if(server != null) {
            server.stop();
        }
        if(client != null) {
            client.stop();
        }
    }
    @Test
    public void testIssue() throws Exception {
        String body = client.toBlocking().retrieve("/issues/12"); (3)
        assertNotNull(body);
        assertEquals("Issue # 12!", body); (4)
    }
    @Test
    public void testShowWithInvalidInteger() {
        HttpClientResponseException e =Assertions.assertThrows(HttpClientResponseException.class, () ->
                client.toBlocking().exchange("/issues/hello"));
        assertEquals(400, e.getStatus().getCode()); (5)
    }
    @Test
    public void testIssueWithoutNumber() {
        HttpClientResponseException e = Assertions.assertThrows(HttpClientResponseException.class, () ->
                client.toBlocking().exchange("/issues/"));
        assertEquals(404, e.getStatus().getCode()); (6)
    }
}

Testing URI Variables

import io.micronaut.context.ApplicationContext
import io.micronaut.http.client.HttpClient
import io.micronaut.http.client.exceptions.HttpClientResponseException
import io.micronaut.runtime.server.EmbeddedServer
import spock.lang.AutoCleanup
import spock.lang.Shared
import spock.lang.Specification
class IssuesControllerTest extends Specification {
    @Shared
    @AutoCleanup (2)
    EmbeddedServer embeddedServer = ApplicationContext.run(EmbeddedServer) (1)
    @Shared
    @AutoCleanup (2)
    HttpClient client = HttpClient.create(embeddedServer.URL) (1)
    void "test issue"() {
        when:
        String body = client.toBlocking().retrieve("/issues/12") (3)
        then:
        body != null
        body == "Issue # 12!" (4)
    }
    void "/issues/{number} with an invalid Integer number responds 400"() {
        when:
        client.toBlocking().exchange("/issues/hello")
        then:
        HttpClientResponseException e = thrown(HttpClientResponseException)
        e.status.code == 400 (5)
    }
    void "/issues/{number} without number responds 404"() {
        when:
        client.toBlocking().exchange("/issues/")
        then:
        HttpClientResponseException e = thrown(HttpClientResponseException)
        e.status.code == 404 (6)
    }
}

Testing URI Variables

import io.micronaut.context.ApplicationContext
import io.micronaut.http.client.exceptions.HttpClientResponseException
import io.micronaut.runtime.server.EmbeddedServer
import io.kotlintest.shouldBe
import io.kotlintest.shouldNotBe
import io.kotlintest.shouldThrow
import io.kotlintest.specs.StringSpec
import io.micronaut.http.client.RxHttpClient
class IssuesControllerTest: StringSpec() {
    val embeddedServer = autoClose( (2)
            ApplicationContext.run(EmbeddedServer::class.java) (1)
    )
    val client = autoClose( (2)
            embeddedServer.applicationContext.createBean(RxHttpClient::class.java, embeddedServer.getURL()) (1)
    )
    init {
        "test issue" {
            val body = client.toBlocking().retrieve("/issues/12") (3)
            body shouldNotBe null
            body shouldBe "Issue # 12!" (4)
        }
        "test issue with invalid integer" {
            val e = shouldThrow<HttpClientResponseException> { client.toBlocking().exchange<Any>("/issues/hello") }
            e.status.code shouldBe 400 (5)
        }
        "test issue without number" {
            val e = shouldThrow<HttpClientResponseException> { client.toBlocking().exchange<Any>("/issues/") }
            e.status.code shouldBe 404 (6)
        }
    }
}

Note that the URI template in the previous example requires that the number variable is specified. You can specify optional URI templates with the syntax: /issues{/number} and by annotating the number parameter with @Nullable.

The following table provides some examples of URI templates and what they match: