fix(postgresql): drop global Dapper underscore name mapping

AGENTS.md

@@ -65,7 +65,7 @@ Both repositories use raw SQL via Dapper. They differ in naming conventions:
 | Columns | PascalCase, via `nameof(DataProtectionKeyEntity.X)` | snake_case literals |
 | Unique index on friendly name | Filtered NONCLUSTERED (`WHERE ... IS NOT NULL`) | `CREATE UNIQUE INDEX IF NOT EXISTS` (NULLs allowed) |
 
-- The PostgreSQL provider sets the global `Dapper.DefaultTypeMap.MatchNamesWithUnderscores = true` so snake_case columns map to `DataProtectionKeyEntity`. This affects the whole host process (documented in the README).
+- The PostgreSQL `SELECT` aliases each snake_case column to its `DataProtectionKeyEntity` property name (`AS "{nameof(...)}"`). Never set the process-wide `Dapper.DefaultTypeMap.MatchNamesWithUnderscores`: it changes column mapping for every Dapper query in the host application.
 - `Delete()` requires `DataProtectionKeyEntity` instances (as returned by `GetAll()`) and deletes by `Id`, row by row in order, in one transaction.
 - Schema and table names are interpolated directly into SQL strings, not parameterized or validated.
 - Defaults are in each provider's `Constants.cs`. Keep the table DDL in sync with the "Database schema" section of `README.md`.

README.md

@@ -117,10 +117,6 @@ app.Services.UseDapperDataProtection();
 app.Run();
 ```
 
-> **Note:** the PostgreSQL provider enables Dapper's snake_case column mapping globally
-> (`Dapper.DefaultTypeMap.MatchNamesWithUnderscores = true`). Keep this in mind if the same
-> application uses Dapper elsewhere.
-
 ## Configuration
 
 Both providers accept an optional `Action<DapperDataProtectionConfig>` to override the defaults:

src/AspNetCore.DataProtection.CustomStorage.Dapper.PostgreSQL/DapperDataProtectionExtensions.cs

@@ -1,5 +1,4 @@
 using System;
-using Dapper;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.DependencyInjection;
 using Npgsql;
@@ -40,8 +39,6 @@ public static IDataProtectionBuilder PersistKeysWithDapperInPostgreSQL(this IDat
 
         var npgsqlDataSource = new NpgsqlDataSourceBuilder(connectionString).Build();
 
-        DefaultTypeMap.MatchNamesWithUnderscores = true;
-
         builder.Services.AddSingleton(npgsqlDataSource);
 
         builder.Services.AddScoped<IDbDataProtectionStorage, PostgreSQLDataProtectionRepository>();

src/AspNetCore.DataProtection.CustomStorage.Dapper.PostgreSQL/PostgreSQLDataProtectionRepository.cs

@@ -16,10 +16,10 @@ public class PostgreSQLDataProtectionRepository : IDbDataProtectionStorage
     private string GetAllQuery() => 
     $"""
         SELECT
-            id,
-            insert_date ,
-            friendly_name,
-            xml
+            id AS "{nameof(DataProtectionKeyEntity.Id)}",
+            insert_date AS "{nameof(DataProtectionKeyEntity.InsertDate)}",
+            friendly_name AS "{nameof(DataProtectionKeyEntity.FriendlyName)}",
+            xml AS "{nameof(DataProtectionKeyEntity.Xml)}"
         FROM {_config.SchemaName}.{_config.TableName};
     """;
 

tests/AspNetCore.DataProtection.CustomStorage.Tests/PostgreSQL/PostgreSqlContainerFixture.cs

@@ -1,7 +1,6 @@
 using System.Threading.Tasks;
 using AspNetCore.DataProtection.CustomStorage.Dapper;
 using AspNetCore.DataProtection.CustomStorage.Dapper.PostgreSQL;
-using Dapper;
 using DotNet.Testcontainers.Builders;
 using Microsoft.Extensions.Options;
 using Npgsql;
@@ -46,7 +45,6 @@ public async ValueTask InitializeAsync()
             }
         };
         NpgsqlDataSource = npgsqlDataSourceBuilder.Build();
-        DefaultTypeMap.MatchNamesWithUnderscores = true;
         SeedDatabase();
         await using var dbConnection = await NpgsqlDataSource.OpenConnectionAsync();
 

tests/AspNetCore.DataProtection.CustomStorage.Tests/PostgreSQL/PostgreSqlDapperDataProtectionExtensionsTests.cs

@@ -1,5 +1,6 @@
 using System.Linq;
 using AspNetCore.DataProtection.CustomStorage.Dapper.PostgreSQL;
+using Dapper;
 using FluentAssertions;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.DependencyInjection;
@@ -25,4 +26,15 @@ public void PersistKeysWithDapperInPostgreSQL_PreservesIncludeErrorDetail(string
         new NpgsqlConnectionStringBuilder(dataSource.ConnectionString).IncludeErrorDetail
             .Should().Be(expected);
     }
+
+    [Fact]
+    public void PersistKeysWithDapperInPostgreSQL_DoesNotEnableMatchNamesWithUnderscores()
+    {
+        DefaultTypeMap.MatchNamesWithUnderscores = false;
+        var services = new ServiceCollection();
+
+        services.AddDataProtection().PersistKeysWithDapperInPostgreSQL("Host=localhost;Database=test");
+
+        DefaultTypeMap.MatchNamesWithUnderscores.Should().BeFalse();
+    }
 }

tests/AspNetCore.DataProtection.CustomStorage.Tests/PostgreSQL/PostgreSqlDataProtectionRepositoryTests.cs

@@ -102,6 +102,21 @@ public async Task GetAllAsync_KeysInserted_ReturnsEntitiesWithIdAndInsertDate()
             .And.OnlyContain(x => x.Id > 0 && x.InsertDate != default);
         entities.Select(x => x.Id).Should().OnlyHaveUniqueItems();
     }
+    [Fact]
+    public async Task GetAllAsync_MatchNamesWithUnderscoresDisabled_MapsAllColumns()
+    {
+        DefaultTypeMap.MatchNamesWithUnderscores = false;
+        await _fixture.ResetDatabaseAsync();
+        var key = new DataProtectionKey { FriendlyName = "MappingFriendlyName", Xml = "MappingXml" };
+        _sut.Insert(key);
+
+        var entity = (await _sut.GetAllAsync()).Should().ContainSingle().Subject;
+
+        entity.Id.Should().BePositive();
+        entity.InsertDate.Should().NotBe(default);
+        entity.FriendlyName.Should().Be(key.FriendlyName);
+        entity.Xml.Should().Be(key.Xml);
+    }
 
     [Fact]
     public void InitializeDb_CustomSchemaAndTable_PersistsKeysInConfiguredTable()