Merge pull request #56 from PandaTechAM/development

ColumnDistinctValue Encrypted Column Null Handling

Author: HaikAsatryan

src/GridifyExtensions/Extensions/QueryableExtensions.cs

@@ -11,15 +11,6 @@ public static class QueryableExtensions
    internal static Dictionary<Type, object> EntityGridifyMapperByType = [];
 
    // ---------- Core helpers ----------
-
-
-   private static Expression<Func<T, object>> CreateSelector<T>(string propertyName)
-   {
-      var p = Expression.Parameter(typeof(T), "x");
-      var body = Expression.Convert(Expression.Property(p, propertyName), typeof(object));
-      return Expression.Lambda<Func<T, object>>(body, p);
-   }
-
    private static FilterMapper<TEntity> RequireMapper<TEntity>()
       where TEntity : class
    {
@@ -145,11 +136,11 @@ public static Task<CursoredResponse<TEntity>> FilterOrderAndGetCursoredAsync<TEn
       query.AsNoTracking()
            .FilterOrderAndGetCursoredAsync(model, x => x, cancellationToken);
 
-   // ---------- Column Distinct ----------
+// ---------- Column Distinct ----------
    [Obsolete("Use ColumnDistinctValueCursoredQueryModel instead.")]
    public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntity>(this IQueryable<TEntity> query,
       ColumnDistinctValueQueryModel model,
-      Func<byte[], string>? decryptor = default,
+      Func<byte[], string>? decryptor = null,
       CancellationToken cancellationToken = default)
       where TEntity : class
    {
@@ -166,37 +157,77 @@ public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntit
          return result;
       }
 
-      // Encrypted path (scalar byte[] or IEnumerable<byte[]>), use mapper-driven selection
       var encryptedQuery = query
                            .ApplyFiltering(model, mapper)
                            .ApplySelect(model.PropertyName, mapper); // IQueryable<object?>
 
-      // Keep original behavior: if no filter, return empty for the obsolete API
       if (string.IsNullOrWhiteSpace(model.Filter))
       {
-         return new PagedResponse<object>([], 1, 1, 0);
+         bool hasNullLike;
+         try
+         {
+            // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
+            hasNullLike = await encryptedQuery.AnyAsync(x => x == null, cancellationToken);
+         }
+         catch (Exception ex) when (ex is InvalidOperationException or NotSupportedException)
+         {
+            // NOTE:
+            // Some providers cannot translate `Any(x => x == null)` when the projection is a COLLECTION
+            // (e.g., IEnumerable<byte[]> coming from a nav). We need to decide what to do without
+            // issuing a second, provider-specific query here.
+            //
+            // UX policy: when the frontend opens distinct-values with NO filter on an encrypted column,
+            // we prefer to SHOW the "null" option rather than hide it due to translation limits.
+            // Therefore we *assume* null-like exists. If you prefer strictness, set `hasNullLike = false`
+            hasNullLike = true;
+         }
+
+         return hasNullLike ? new PagedResponse<object>([null!], 1, 1, 1) : new PagedResponse<object>([], 1, 1, 0);
       }
 
       var selected = await encryptedQuery.FirstOrDefaultAsync(cancellationToken);
-      if (selected is null) return new PagedResponse<object>([], 1, 1, 0);
-      if (decryptor is null) throw new KeyNotFoundException("Decryptor is required for encrypted properties.");
+      switch (selected)
+      {
+         case null:
+         case byte[]
+         {
+            Length: 0
+         }:
+            return new PagedResponse<object>([null!], 1, 1, 1);
+         case byte[] sb:
+            return decryptor == null
+               ? throw new KeyNotFoundException("Decryptor is required for encrypted properties.")
+               : new PagedResponse<object>([decryptor(sb)], 1, 1, 1);
+      }
 
-      object? decrypted = selected switch
+      if (selected is not IEnumerable<byte[]> seq)
       {
-         byte[] b => decryptor(b),
-         IEnumerable<byte[]> bs => bs.FirstOrDefault() is byte[] fb ? decryptor(fb) : null,
-         _ => throw new InvalidCastException("Encrypted selector did not return a byte[] or IEnumerable<byte[]> value.")
-      };
+         throw new InvalidCastException("Encrypted selector did not return a byte[] or IEnumerable<byte[]> value.");
+      }
+
+      var ng = ((System.Collections.IEnumerable)seq).GetEnumerator();
+      using var ng1 = ng as IDisposable;
+
+      if (!ng.MoveNext())
+      {
+         return new PagedResponse<object>([null!], 1, 1, 1);
+      }
 
-      return decrypted is null
-         ? new PagedResponse<object>([], 1, 1, 0)
-         : new PagedResponse<object>([decrypted], 1, 1, 1);
+      var firstObj = ng.Current;
+      if (firstObj is not byte[] first || first.Length == 0)
+      {
+         return new PagedResponse<object>([null!], 1, 1, 1);
+      }
+
+      return decryptor == null
+         ? throw new KeyNotFoundException("Decryptor is required for encrypted properties.")
+         : new PagedResponse<object>([decryptor(first)], 1, 1, 1);
    }
 
    public static async Task<CursoredResponse<object?>> ColumnDistinctValuesAsync<TEntity>(
       this IQueryable<TEntity> query,
       ColumnDistinctValueCursoredQueryModel model,
-      Func<byte[], string>? decryptor = default,
+      Func<byte[], string>? decryptor = null,
       CancellationToken cancellationToken = default)
       where TEntity : class
    {
@@ -217,7 +248,10 @@ public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntit
          {
             // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
             hasNull = await baseQuery.AnyAsync(x => x == null, cancellationToken);
-            if (hasNull && take > 0) take -= 1;
+            if (hasNull && take > 0)
+            {
+               take -= 1;
+            }
          }
 
          var result = await baseQuery
@@ -227,55 +261,86 @@ public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntit
                             .ToListAsync(cancellationToken);
 
          if (!filterEmpty || !hasNull)
+         {
             return new CursoredResponse<object?>(result!, model.PageSize);
+         }
 
          if (result.Count > 0 && ReferenceEquals(result[^1], null))
+         {
             result.RemoveAt(result.Count - 1);
+         }
 
          result.Insert(0, null!);
          return new CursoredResponse<object?>(result!, model.PageSize);
       }
 
-      // Encrypted path (scalar byte[] or IEnumerable<byte[]>)
+      // Encrypted path
       var encryptedQuery = query
                            .ApplyFiltering(gridifyModel, mapper)
                            .ApplySelect(model.PropertyName, mapper); // IQueryable<object?>
 
       if (string.IsNullOrWhiteSpace(model.Filter))
       {
-         // EF-translatable: only checks if the projection itself is NULL in DB
-         // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
-         var hasNull = await encryptedQuery.AnyAsync(x => x == null, cancellationToken);
+         bool hasNullLike;
+         try
+         {
+            // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
+            hasNullLike = await encryptedQuery.AnyAsync(x => x == null, cancellationToken);
+         }
+         catch (Exception ex) when (ex is InvalidOperationException or NotSupportedException)
+         {
+            // NOTE:
+            // Some providers cannot translate `Any(x => x == null)` when the projection is a COLLECTION
+            // (e.g., IEnumerable<byte[]> coming from a nav). We need to decide what to do without
+            // issuing a second, provider-specific query here.
+            //
+            // UX policy: when the frontend opens distinct-values with NO filter on an encrypted column,
+            // we prefer to SHOW the "null" option rather than hide it due to translation limits.
+            // Therefore we *assume* null-like exists. If you prefer strictness, set `hasNullLike = false`
+            hasNullLike = true;
+         }
 
-         return hasNull
+         return hasNullLike
             ? new CursoredResponse<object?>([null], model.PageSize)
             : new CursoredResponse<object?>([], model.PageSize);
       }
 
       var selected = await encryptedQuery.FirstOrDefaultAsync(cancellationToken);
-      if (selected is null)
+      switch (selected)
       {
-         return new CursoredResponse<object?>([], model.PageSize);
+         case null:
+         case byte[]
+         {
+            Length: 0
+         }:
+            return new CursoredResponse<object?>([null], model.PageSize);
+         case byte[] when decryptor == null:
+            throw new KeyNotFoundException("Decryptor is required for encrypted properties.");
+         case byte[] sb:
+            return new CursoredResponse<object?>([decryptor(sb)], model.PageSize);
       }
 
-      if (decryptor is null)
+      if (selected is not IEnumerable<byte[]> seq)
       {
-         throw new KeyNotFoundException("Decryptor is required for encrypted properties.");
+         throw new InvalidCastException("Encrypted selector did not return a byte[] or IEnumerable<byte[]> value.");
       }
 
-      object? decrypted = selected switch
+      var ng = ((System.Collections.IEnumerable)seq).GetEnumerator();
+      using var ng1 = ng as IDisposable;
+      if (!ng.MoveNext())
       {
-         byte[] b => decryptor(b),
-         IEnumerable<byte[]> bs => bs.FirstOrDefault() is
-            { } fb
-            ? decryptor(fb)
-            : null,
-         _ => throw new InvalidCastException("Encrypted selector did not return a byte[] or IEnumerable<byte[]> value.")
-      };
+         return new CursoredResponse<object?>([null], model.PageSize);
+      }
+
+      var firstObj = ng.Current;
+      if (firstObj is not byte[] first || first.Length == 0)
+      {
+         return new CursoredResponse<object?>([null], model.PageSize);
+      }
 
-      return decrypted is null
-         ? new CursoredResponse<object?>([], model.PageSize)
-         : new CursoredResponse<object?>([decrypted], model.PageSize);
+      return decryptor == null
+         ? throw new KeyNotFoundException("Decryptor is required for encrypted properties.")
+         : new CursoredResponse<object?>([decryptor(first)], model.PageSize);
    }
 
    // ---------- Aggregation ----------
@@ -309,12 +374,13 @@ public static IEnumerable<MappingModel> GetMappings<TEntity>()
                     .Select(x => new MappingModel
                     {
                        Name = x.From,
-                       Type = x.To.Body is UnaryExpression ue
-                          ? ue.Operand.Type.Name
-                          : x.To.Body is MethodCallExpression mc
-                             ? ((mc.Arguments.LastOrDefault() as LambdaExpression)?.ReturnType?.Name)
-                               ?? x.To.Body.Type.Name
-                             : x.To.Body.Type.Name
+                       Type = x.To.Body switch
+                       {
+                          UnaryExpression ue => ue.Operand.Type.Name,
+                          MethodCallExpression mc => (mc.Arguments.LastOrDefault() as LambdaExpression)?.ReturnType.Name
+                                                     ?? x.To.Body.Type.Name,
+                          _ => x.To.Body.Type.Name
+                       }
                     });
    }
 }

src/GridifyExtensions/GridifyExtensions.csproj

@@ -8,13 +8,13 @@
         <PackageReadmeFile>Readme.md</PackageReadmeFile>
         <Authors>Pandatech</Authors>
         <Copyright>MIT</Copyright>
-        <Version>2.1.3</Version>
+        <Version>2.1.4</Version>
         <PackageId>Pandatech.GridifyExtensions</PackageId>
         <Title>Pandatech.Gridify.Extensions</Title>
         <PackageTags>Pandatech, library, Gridify, Pagination, Filters</PackageTags>
         <Description>Pandatech.Gridify.Extensions simplifies and extends the functionality of the Gridify NuGet package. It provides additional extension methods and functionality to streamline data filtering and pagination, making it more intuitive and powerful to use in .NET applications. Our enhancements ensure more flexibility, reduce boilerplate code, and improve overall developer productivity when working with Gridify.</Description>
         <RepositoryUrl>https://github.com/PandaTechAM/be-lib-gridify-extensions</RepositoryUrl>
-        <PackageReleaseNotes>ColumnDistinctValue Encryption Handling Upgrade</PackageReleaseNotes>
+        <PackageReleaseNotes>ColumnDistinctValue Encrypted Column Null Handling</PackageReleaseNotes>
     </PropertyGroup>
 
     <ItemGroup>