From 3672c300875e1d49baf0858d6d3456bf1b051685 Mon Sep 17 00:00:00 2001
From: Mark Paluch <mpaluch@vmware.com>
Date: Tue, 24 May 2022 13:33:25 +0200
Subject: [PATCH] Skip EnumCodec registration if the builder has no mappings.

Also, improve PostgresTypes safety if the collection of type names is empty.

[resolves #515]

Signed-off-by: Mark Paluch <mpaluch@vmware.com>
---
 .../io/r2dbc/postgresql/codec/EnumCodec.java   |  4 ++++
 .../r2dbc/postgresql/codec/PostgresTypes.java  |  7 +++++++
 .../codec/EnumCodecIntegrationTests.java       | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/src/main/java/io/r2dbc/postgresql/codec/EnumCodec.java b/src/main/java/io/r2dbc/postgresql/codec/EnumCodec.java
index d221bdfb..f736969f 100644
--- a/src/main/java/io/r2dbc/postgresql/codec/EnumCodec.java
+++ b/src/main/java/io/r2dbc/postgresql/codec/EnumCodec.java
@@ -212,6 +212,10 @@ public CodecRegistrar build() {
 
             Map<String, Class<? extends Enum<?>>> mapping = new LinkedHashMap<>(this.mapping);
 
+            if (mapping.isEmpty()) {
+                return (connection, allocator, registry) -> Mono.empty();
+            }
+
             return (connection, allocator, registry) -> {
 
                 List<String> missing = new ArrayList<>(mapping.keySet());
diff --git a/src/main/java/io/r2dbc/postgresql/codec/PostgresTypes.java b/src/main/java/io/r2dbc/postgresql/codec/PostgresTypes.java
index cb1d7b7d..1ce5747e 100644
--- a/src/main/java/io/r2dbc/postgresql/codec/PostgresTypes.java
+++ b/src/main/java/io/r2dbc/postgresql/codec/PostgresTypes.java
@@ -25,6 +25,7 @@
 
 import java.util.Objects;
 import java.util.StringJoiner;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.regex.Pattern;
 
 /**
@@ -85,6 +86,7 @@ public Mono<PostgresType> lookupType(String typeName) {
     public Flux<PostgresType> lookupTypes(Iterable<String> typeNames) {
 
         StringJoiner joiner = new StringJoiner(",", "(", ")");
+        AtomicBoolean hasType = new AtomicBoolean();
 
         typeNames.forEach(typeName -> {
 
@@ -92,9 +94,14 @@ public Flux<PostgresType> lookupTypes(Iterable<String> typeNames) {
                 throw new IllegalArgumentException(String.format("Invalid typename %s", typeName));
             }
 
+            hasType.set(true);
             joiner.add("'" + typeName + "'");
         });
 
+        if (!hasType.get()) {
+            return Flux.empty();
+        }
+
         return this.connection.createStatement(String.format(SELECT_PG_TYPE, "IN", joiner, "")).execute()
             .flatMap(it -> it.map((row, rowMetadata) -> {
 
diff --git a/src/test/java/io/r2dbc/postgresql/codec/EnumCodecIntegrationTests.java b/src/test/java/io/r2dbc/postgresql/codec/EnumCodecIntegrationTests.java
index a39e9757..64c5ba4a 100644
--- a/src/test/java/io/r2dbc/postgresql/codec/EnumCodecIntegrationTests.java
+++ b/src/test/java/io/r2dbc/postgresql/codec/EnumCodecIntegrationTests.java
@@ -54,6 +54,24 @@ protected void customize(PostgresqlConnectionConfiguration.Builder builder) {
         builder.codecRegistrar(EnumCodec.builder().withEnum("my_enum_with_codec", MyEnum.class).build());
     }
 
+    @Test
+    void shouldNotRegisterIfEmpty() {
+
+        PostgresqlConnectionConfiguration configuration = PostgresqlConnectionConfiguration.builder()
+            .database(SERVER.getDatabase())
+            .host(SERVER.getHost())
+            .port(SERVER.getPort())
+            .password(SERVER.getPassword())
+            .username(SERVER.getUsername())
+            .codecRegistrar(EnumCodec.builder().build())
+            .build();
+
+        PostgresqlConnectionFactory connectionFactory = new PostgresqlConnectionFactory(configuration);
+        connectionFactory.create().flatMap(PostgresqlConnection::close).as(StepVerifier::create).verifyComplete();
+
+        // we cannot really assert logs so that's up to you.
+    }
+
     @Test
     void shouldReportUnresolvableTypes() {