Adds a default validation exception handler

http-inject-plugin/pom.xml

@@ -38,6 +38,28 @@
       <scope>provided</scope>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>io.javalin</groupId>
+      <artifactId>javalin</artifactId>
+      <version>6.7.0</version>
+      <scope>provided</scope>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.avaje</groupId>
+      <artifactId>avaje-jex</artifactId>
+      <version>3.3</version>
+      <scope>provided</scope>
+      <optional>true</optional>
+    </dependency>
+    <dependency>
+      <groupId>io.helidon.webserver</groupId>
+      <artifactId>helidon-webserver</artifactId>
+      <version>4.3.2</version>
+      <scope>provided</scope>
+      <optional>true</optional>
+    </dependency>
+
   </dependencies>
 
   <build>

http-inject-plugin/src/main/java/io/avaje/http/inject/HelidonHandler.java

@@ -0,0 +1,32 @@
+package io.avaje.http.inject;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+
+import io.avaje.http.api.ValidationException;
+import io.helidon.common.Weight;
+import io.helidon.webserver.http.HttpFeature;
+import io.helidon.webserver.http.HttpRouting.Builder;
+import io.helidon.webserver.http.ServerRequest;
+import io.helidon.webserver.http.ServerResponse;
+
+@Weight(-67) // execute first so that it can be overridden by a custom error handler.
+final class HelidonHandler implements HttpFeature {
+
+  @Override
+  public void setup(Builder routing) {
+
+    routing.error(ValidationException.class, this::handle);
+  }
+
+  private void handle(ServerRequest req, ServerResponse res, ValidationException ex) {
+    try (var os =
+        res.status(ex.getStatus())
+            .header("Content-Type", "application/problem+json")
+            .outputStream()) {
+      new ValidationResponse(ex.getStatus(), ex.getErrors(), req.path().rawPath()).toJson(os);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
+}

http-inject-plugin/src/main/java/io/avaje/http/inject/HttpValidatorHandler.java

@@ -0,0 +1,62 @@
+package io.avaje.http.inject;
+
+import io.avaje.http.api.AvajeJavalinPlugin;
+import io.avaje.inject.BeanScopeBuilder;
+import io.avaje.inject.spi.InjectPlugin;
+import io.avaje.inject.spi.PluginProvides;
+import io.avaje.jex.Routing.HttpService;
+import io.avaje.spi.ServiceProvider;
+import io.helidon.webserver.http.HttpFeature;
+
+/** Plugin for avaje inject that provides a default Validator Handler */
+@ServiceProvider
+@PluginProvides(
+    providesStrings = {
+      "io.helidon.webserver.http.HttpFeature",
+      "io.avaje.http.api.AvajeJavalinPlugin",
+      "io.avaje.jex.Routing.HttpService",
+    })
+public final class HttpValidatorHandler implements InjectPlugin {
+
+  enum Server {
+    HELIDON("io.helidon.webserver.http.HttpFeature"),
+    JAVALIN("io.javalin.plugin.Plugin"),
+    JEX("io.avaje.jex.Routing.HttpService");
+    String register;
+    Server(String register) {
+      this.register = register;
+    }
+  }
+
+  private static final Server type = server();
+
+  private static Server server() {
+    for (var register : Server.values()) {
+      try {
+        Class.forName(register.register);
+        return register;
+      } catch (ClassNotFoundException e) {
+        // nothing
+      }
+    }
+    return null;
+  }
+
+  @Override
+  public void apply(BeanScopeBuilder builder) {
+    if (type == null) {
+      return;
+    }
+    switch (type) {
+      case HELIDON:
+        builder.provideDefault(HttpFeature.class, HelidonHandler::new);
+        break;
+      case JAVALIN:
+        builder.provideDefault(AvajeJavalinPlugin.class, JavalinHandler::new);
+        break;
+      case JEX:
+        builder.provideDefault(HttpService.class, JexHandler::new);
+        break;
+    }
+  }
+}

http-inject-plugin/src/main/java/io/avaje/http/inject/JavalinHandler.java

@@ -0,0 +1,25 @@
+package io.avaje.http.inject;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+
+import io.avaje.http.api.AvajeJavalinPlugin;
+import io.avaje.http.api.ValidationException;
+import io.javalin.config.JavalinConfig;
+import io.javalin.http.Context;
+
+final class JavalinHandler extends AvajeJavalinPlugin {
+  @Override
+  public void onStart(JavalinConfig config) {
+    config.router.mount(r -> r.exception(ValidationException.class, this::handler));
+  }
+
+  private void handler(ValidationException ex, Context ctx) {
+    try (var os =
+        ctx.contentType("application/problem+json").status(ex.getStatus()).outputStream()) {
+      new ValidationResponse(ex.getStatus(), ex.getErrors(), ctx.path()).toJson(os);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
+}

http-inject-plugin/src/main/java/io/avaje/http/inject/JexHandler.java

@@ -0,0 +1,27 @@
+package io.avaje.http.inject;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+
+import io.avaje.http.api.ValidationException;
+import io.avaje.jex.Routing;
+import io.avaje.jex.Routing.HttpService;
+import io.avaje.jex.http.Context;
+
+final class JexHandler implements HttpService {
+
+  @Override
+  public void add(Routing arg0) {
+    arg0.error(ValidationException.class, this::handler);
+  }
+
+  private void handler(Context ctx, ValidationException ex) {
+
+    try (var os =
+        ctx.contentType("application/problem+json").status(ex.getStatus()).outputStream()) {
+      new ValidationResponse(ex.getStatus(), ex.getErrors(), ctx.path()).toJson(os);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
+}

http-inject-plugin/src/main/java/io/avaje/http/inject/ValidationResponse.java

@@ -0,0 +1,120 @@
+package io.avaje.http.inject;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.List;
+
+import io.avaje.http.api.ValidationException.Violation;
+
+public class ValidationResponse {
+
+  private static String type = "tag:io.avaje.http.api.ValidationException";
+  private static String title = "Request Failed Validation";
+  private static String detail = "You tried to call this endpoint, but your data failed validation";
+  private final int status;
+  private final List<Violation> errors;
+  private final String instance;
+
+  public ValidationResponse(int status, List<Violation> errors, String instance) {
+    this.status = status;
+    this.errors = errors;
+    this.instance = instance;
+  }
+
+  // custom serialize as this is a simple class
+  public void toJson(OutputStream os) throws IOException {
+    try (Writer writer = new OutputStreamWriter(os, "UTF-8")) {
+      writeJsonInternal(writer);
+    }
+  }
+
+  private void writeJsonInternal(Writer writer) throws IOException {
+    writer.write('{');
+    writeKeyValue("type", type, writer);
+    writer.write(',');
+    writeKeyValue("title", title, writer);
+    writer.write(',');
+    writeKeyValue("detail", detail, writer);
+    writer.write(',');
+    writeKeyValue("instance", instance, writer);
+    writer.write(',');
+    // status is a number, so no quotes or escaping needed
+    writer.write("\"status\":");
+    writer.write(String.valueOf(status));
+    writer.write(",\"errors\":[");
+    for (int i = 0; i < errors.size(); i++) {
+      if (i > 0) {
+        writer.write(',');
+      }
+      var e = errors.get(i);
+      writer.write('{');
+      writeKeyValue("path", e.getPath(), writer);
+      writer.write(',');
+      writeKeyValue("field", e.getField(), writer);
+      writer.write(',');
+      writeKeyValue("message", e.getMessage(), writer);
+      writer.write('}');
+    }
+
+    writer.write(']');
+    writer.write('}');
+    writer.flush();
+  }
+
+  /** Writes a JSON key-value pair where the value is a string, handling quotes and escaping. */
+  private void writeKeyValue(String key, String value, Writer writer) throws IOException {
+    writer.write('"');
+    writer.write(key);
+    writer.write("\":");
+    writeEscapedJsonString(value, writer);
+  }
+
+  /**
+   * Writes the given string to the writer, JSON-escaping it and wrapping it in quotes. Writes
+   * 'null' (the JSON literal) if the input string is null.
+   */
+  private static void writeEscapedJsonString(String s, Writer writer) throws IOException {
+    if (s == null) {
+      writer.write("null");
+      return;
+    }
+
+    writer.write('"');
+    for (int i = 0; i < s.length(); i++) {
+      char ch = s.charAt(i);
+      switch (ch) {
+        case '"':
+          writer.write("\\\"");
+          break;
+        case '\\':
+          writer.write("\\\\");
+          break;
+        case '\b':
+          writer.write("\\b");
+          break;
+        case '\f':
+          writer.write("\\f");
+          break;
+        case '\n':
+          writer.write("\\n");
+          break;
+        case '\r':
+          writer.write("\\r");
+          break;
+        case '\t':
+          writer.write("\\t");
+          break;
+        default:
+          // Check for control characters that must be escaped
+          if (ch < ' ' || ch >= 0x7F && ch <= 0x9F) {
+            writer.write(String.format("\\u%04x", (int) ch));
+          } else {
+            writer.write(ch);
+          }
+      }
+    }
+    writer.write('"');
+  }
+}

http-inject-plugin/src/main/java/module-info.java

@@ -1,8 +1,13 @@
+import io.avaje.http.inject.DefaultResolverProvider;
+import io.avaje.http.inject.HttpValidatorHandler;
+
 module io.avaje.http.plugin {
 
   requires io.avaje.http.api;
   requires io.avaje.inject;
   requires static io.avaje.spi;
-
-  provides io.avaje.inject.spi.InjectExtension with io.avaje.http.inject.DefaultResolverProvider;
+  requires static io.avaje.jex;
+  requires static io.javalin;
+  requires static io.helidon.webserver;
+  provides io.avaje.inject.spi.InjectExtension with DefaultResolverProvider, HttpValidatorHandler;
 }

pom.xml

@@ -44,7 +44,6 @@
     <module>http-client</module>
     <module>http-client-gson-adapter</module>
     <module>http-client-moshi-adapter</module>
-    <module>http-inject-plugin</module>
     <module>http-generator-core</module>
     <module>http-generator-javalin</module>
     <module>http-generator-sigma</module>
@@ -68,6 +67,7 @@
         <jdk>[21,)</jdk>
       </activation>
       <modules>
+        <module>http-inject-plugin</module>
         <module>htmx-nima</module>
         <module>htmx-nima-jstache</module>
         <module>http-generator-helidon</module>