Support for never expire cache items when expiration time is null

CachingTest/DatabaseOperationsTests.cs

@@ -273,17 +273,35 @@ await Assert.ThrowsAsync<InvalidOperationException>(() =>
     }
 
     [Fact]
-    public async Task SetCacheItem_WithNoExpiration_ThrowsInvalidOperationException()
+    public async Task SetCacheItem_WithNoExpiration_Should_Work()
     {
         // Arrange
         await InitializeAsync();
         Assert.NotNull(_databaseOperations);
         var key = "no-expiration-test";
-        var value = new byte[] { 1, 2, 3 };
+        var value = new byte[]
+        {
+            1, 2, 3
+        };
 
-        // Act & Assert
-        await Assert.ThrowsAsync<InvalidOperationException>(() =>
-            _databaseOperations!.SetCacheItemAsync(key, value, new DistributedCacheEntryOptions(), CancellationToken.None));
+        var operations = new DatabaseOperations(Options.Create(
+                new PostgreSqlCacheOptions
+            {
+                ConnectionString = _postgresContainer.GetConnectionString(),
+                SchemaName = "cache",
+                TableName = "distributed_cache",
+                CreateInfrastructure = true,
+                DefaultSlidingExpiration = null
+            }),
+            _logger);
+
+        // Act
+        await operations.SetCacheItemAsync(key, value, new DistributedCacheEntryOptions(), CancellationToken.None);
+
+        var result = await operations.GetCacheItemAsync(key, CancellationToken.None);
+
+        // Assert
+        Assert.NotNull(result);
     }
 
     [Fact]

CachingTest/DatabaseResilienceIntegrationTests.cs

@@ -172,10 +172,6 @@
             dbOperations.SetCacheItem("test-key", new byte[] { 1, 2, 3 },
                 new DistributedCacheEntryOptions { AbsoluteExpiration = DateTime.UtcNow.AddMinutes(-1) }));
 
-        Assert.Throws<InvalidOperationException>(() =>
-            dbOperations.SetCacheItem("test-key", new byte[] { 1, 2, 3 },
-                new DistributedCacheEntryOptions()));
-
         await Assert.ThrowsAsync<ArgumentOutOfRangeException>(() =>
             dbOperations.SetCacheItemAsync("test-key", new byte[] { 1, 2, 3 },
                 new DistributedCacheEntryOptions { AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(-1) },
@@ -183,7 +179,7 @@
     }
 
     [Fact]
     public async Task DatabaseOperations_PerformanceUnderFailure_ShouldNotExceedThresholds()
     {
         // Arrange
         var invalidConnectionString = "Host=nonexistent-host;Database=test;Username=test;Password=test";
@@ -354,7 +350,7 @@
     }
 
     [Fact]
     public async Task DatabaseOperations_LongRunningOperations_ShouldRespectTimeout()
     {
         // Arrange - Use a very short timeout to test timeout behavior
         var invalidConnectionString = "Host=nonexistent-host;Database=test;Username=test;Password=test";

CachingTest/SqlCommandsTests.cs

@@ -46,7 +46,7 @@ public void GetCacheItemSql_WithValidParameters_GeneratesCorrectSql()
         // Assert
         Assert.Contains("SELECT \"Value\"", sql);
         Assert.Contains("FROM \"test_schema\".\"test_table\"", sql);
-        Assert.Contains("WHERE \"Id\" = @Id AND @UtcNow <= \"ExpiresAtTime\"", sql);
+        Assert.Contains("WHERE \"Id\" = @Id AND (\"ExpiresAtTime\" IS NULL OR @UtcNow <= \"ExpiresAtTime\")", sql);
     }
 
     [Fact]
@@ -83,7 +83,7 @@ public void UpdateCacheItemSql_WithValidParameters_GeneratesCorrectSql()
         Assert.Contains("UPDATE \"test_schema\".\"test_table\"", sql);
         Assert.Contains("SET \"ExpiresAtTime\" = LEAST(\"AbsoluteExpiration\", @UtcNow + \"SlidingExpirationInSeconds\" * interval '1 second')", sql);
         Assert.Contains("WHERE \"Id\" = @Id", sql);
-        Assert.Contains("AND @UtcNow <= \"ExpiresAtTime\"", sql);
+        Assert.Contains("AND (\"ExpiresAtTime\" IS NULL OR @UtcNow <= \"ExpiresAtTime\")", sql);
         Assert.Contains("AND \"SlidingExpirationInSeconds\" IS NOT NULL", sql);
         Assert.Contains("AND (\"AbsoluteExpiration\" IS NULL OR \"AbsoluteExpiration\" <> \"ExpiresAtTime\")", sql);
     }

Extensions.Caching.PostgreSql/DatabaseOperations.cs

@@ -205,13 +205,10 @@ public void SetCacheItem(string key, byte[] value, DistributedCacheEntryOptions
                 var utcNow = SystemClock.UtcNow;
 
                 var absoluteExpiration = GetAbsoluteExpiration(utcNow, options);
-                ValidateOptions(options.SlidingExpiration, absoluteExpiration);
 
                 using var connection = ConnectionFactory();
 
-                var expiresAtTime = options.SlidingExpiration == null
-                    ? absoluteExpiration!.Value
-                    : utcNow.Add(options.SlidingExpiration.Value);
+                var expiresAtTime = GetExpiresAtTime(utcNow, absoluteExpiration, options.SlidingExpiration);
 
                 var setCache = new CommandDefinition(
                     SqlCommands.SetCacheSql,
@@ -238,13 +235,10 @@ await ExecuteWithResilienceAsync(async () =>
                 var utcNow = SystemClock.UtcNow;
 
                 var absoluteExpiration = GetAbsoluteExpiration(utcNow, options);
-                ValidateOptions(options.SlidingExpiration, absoluteExpiration);
 
                 await using var connection = ConnectionFactory();
 
-                var expiresAtTime = options.SlidingExpiration == null
-                    ? absoluteExpiration!.Value
-                    : utcNow.Add(options.SlidingExpiration.Value);
+                var expiresAtTime = GetExpiresAtTime(utcNow, absoluteExpiration, options.SlidingExpiration);
 
                 var setCache = new CommandDefinition(
                     SqlCommands.SetCacheSql,
@@ -336,13 +330,17 @@ private async Task<byte[]> GetCacheItemAsync(string key, bool includeValue, Canc
             return absoluteExpiration;
         }
 
-        private void ValidateOptions(TimeSpan? slidingExpiration, DateTimeOffset? absoluteExpiration)
+        private DateTimeOffset? GetExpiresAtTime(DateTimeOffset utcNow, DateTimeOffset? absoluteExpiration, TimeSpan? slidingExpiration)
         {
-            if (!slidingExpiration.HasValue && !absoluteExpiration.HasValue)
+            if (!slidingExpiration.HasValue)
             {
-                throw new InvalidOperationException("Either absolute or sliding expiration needs " +
-                    "to be provided.");
+                return absoluteExpiration;
             }
+
+            var expiration = utcNow.Add(slidingExpiration.Value);
+
+            // Pick whichever comes first: the absolute or the sliding deadline
+            return absoluteExpiration.HasValue && expiration > absoluteExpiration.Value ? absoluteExpiration : expiration;
         }
 
         /// <summary>

Extensions.Caching.PostgreSql/PostGreSqlCacheOptions.cs

@@ -79,7 +79,7 @@ public class PostgreSqlCacheOptions : IOptions<PostgreSqlCacheOptions>
         /// The default sliding expiration set for a cache entry if neither Absolute or SlidingExpiration has been set explicitly.
         /// By default, its 20 minutes.
         /// </summary>
-        public TimeSpan DefaultSlidingExpiration { get; set; } = TimeSpan.FromMinutes(20);
+        public TimeSpan? DefaultSlidingExpiration { get; set; } = TimeSpan.FromMinutes(20);
 
         /// <summary>
         /// If set to true this instance of the cache will not remove expired items. 

Extensions.Caching.PostgreSql/PostgreSqlCache.cs

@@ -9,7 +9,7 @@ namespace Community.Microsoft.Extensions.Caching.PostgreSql
     internal sealed class PostgreSqlCache : IDistributedCache
     {
         private readonly IDatabaseOperations _dbOperations;
-        private readonly TimeSpan _defaultSlidingExpiration;
+        private readonly TimeSpan? _defaultSlidingExpiration;
 
         [Obsolete("Do not use constructor directly instead pull IDistributedCache from DI. For this add 'services.AddDistributedPostgreSqlCache'")]
         public PostgreSqlCache(

Extensions.Caching.PostgreSql/SqlCommandTypes.cs

@@ -12,7 +12,7 @@ public record ItemIdUtcNow
 public record ItemFull
 {
     public string Id { get; internal set; }
-    public DateTimeOffset ExpiresAtTime { get; internal set; }
+    public DateTimeOffset? ExpiresAtTime { get; internal set; }
     public byte[] Value { get; internal set; }
     public double? SlidingExpirationInSeconds { get; internal set; }
     public DateTimeOffset? AbsoluteExpiration { get; internal set; }

Extensions.Caching.PostgreSql/SqlCommands.cs

@@ -29,7 +29,7 @@ CREATE TABLE IF NOT EXISTS "{_schemaName}"."{_tableName}"
         $"""
         SELECT "Value"
         FROM "{_schemaName}"."{_tableName}"
-        WHERE "Id" = @Id AND @UtcNow <= "ExpiresAtTime"
+        WHERE "Id" = @Id AND ("ExpiresAtTime" IS NULL OR @UtcNow <= "ExpiresAtTime")
         """;
 
     public string SetCacheSql =>
@@ -49,7 +49,7 @@ UPDATE SET
         UPDATE "{_schemaName}"."{_tableName}"
         SET "ExpiresAtTime" = LEAST("AbsoluteExpiration", @UtcNow + "SlidingExpirationInSeconds" * interval '1 second')
         WHERE "Id" = @Id
-            AND @UtcNow <= "ExpiresAtTime" 
+            AND ("ExpiresAtTime" IS NULL OR @UtcNow <= "ExpiresAtTime")
             AND "SlidingExpirationInSeconds" IS NOT NULL
             AND ("AbsoluteExpiration" IS NULL OR "AbsoluteExpiration" <> "ExpiresAtTime")
         """;