cursore implementation

Author: HaikAsatryan

src/GridifyExtensions/Extensions/QueryableExtensions.cs

@@ -75,26 +75,12 @@ public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntit
 
         if (!mapper!.IsEncrypted(model.PropertyName))
         {
-            if (mapper!.IsArray(model.PropertyName))
-            {
-
-                var data = await query.ApplyFiltering(model, mapper)
-                                      .ApplySelect(model.PropertyName, mapper)
-                                      .ToArrayAsync(cancellationToken);
-
-                var result = data.SelectMany(item => ((IList)item).Cast<object>())
-                                 .Distinct()
-                                 .OrderBy(x => x)
-                                 .ToList();
-
-                return new PagedResponse<object>(result, model.Page, model.PageSize, result.Count);
-            }
 
             return await query
                 .ApplyFiltering(model, mapper)
                 .ApplySelect(model.PropertyName, mapper)
                 .Distinct()
-                .OrderBy(x => x)
+                .OrderBy(x => x ?? 0)
                 .GetPagedAsync(model, cancellationToken);
         }
 
@@ -111,6 +97,41 @@ public static async Task<PagedResponse<object>> ColumnDistinctValuesAsync<TEntit
         var decryptedItem = decryptor!((byte[])item);
         return new PagedResponse<object>([decryptedItem], 1, 1, 1);
     }
+    
+    public static async Task<CursoredResponse<object>> ColumnDistinctValuesAsync<TEntity>(this IQueryable<TEntity> query,
+        ColumnDistinctValueCursoredQueryModel model, Func<byte[], string>? decryptor = default,
+        CancellationToken cancellationToken = default)
+    {
+        var mapper = EntityGridifyMapperByType[typeof(TEntity)] as FilterMapper<TEntity>;
+
+        var gridifyModel = ColumnDistinctValueCursoredQueryModel.ToGridifyQueryModel(model);
+
+        if (!mapper!.IsEncrypted(model.PropertyName))
+        {
+
+            var result = await query
+                .ApplyFiltering(gridifyModel, mapper)
+                .ApplySelect(model.PropertyName, mapper)
+                .Distinct()
+                .OrderBy(x => x ?? 0)
+                .ToListAsync(cancellationToken: cancellationToken);
+            
+            return new CursoredResponse<object>(result, model.PageSize);
+        }
+
+        var item = await query
+            .ApplyFiltering(gridifyModel, mapper)
+            .Select(CreateSelector<TEntity>(model.PropertyName))
+            .FirstOrDefaultAsync(cancellationToken);
+
+        if (item is null)
+        {
+            return new CursoredResponse<object>([], model.PageSize);
+        }
+
+        var decryptedItem = decryptor!((byte[])item);
+        return new CursoredResponse<object>([decryptedItem], model.PageSize);
+    }
 
     public static async Task<object> AggregateAsync<TEntity>(this IQueryable<TEntity> query,
       AggregateQueryModel model,

src/GridifyExtensions/GridifyExtensions.csproj

@@ -25,6 +25,7 @@
     <ItemGroup>
         <PackageReference Include="Gridify.EntityFramework" Version="2.14.2" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.6" />
+        <PackageReference Include="PandaTech.BaseConverter" Version="4.0.3" />
     </ItemGroup>
 
 </Project>

src/GridifyExtensions/Models/ColumnDistinctValueCursoredQueryModel.cs

@@ -0,0 +1,37 @@
+using GridifyExtensions.Exceptions;
+
+namespace GridifyExtensions.Models;
+
+public class ColumnDistinctValueCursoredQueryModel
+{
+    private int _pageSize = 10;
+
+    public required int PageSize
+    {
+        get => _pageSize;
+        set
+        {
+            value = value switch
+            {
+                <= 0 => throw new GridifyException($"{nameof(PageSize)} should be positive number."),
+                > 500 => 500,
+                _ => value
+            };
+
+            _pageSize = value;
+        }
+    }
+
+    public required string PropertyName { get; set; }
+    public string Filter { get; set; } = null!;
+    
+    public static GridifyQueryModel ToGridifyQueryModel(ColumnDistinctValueCursoredQueryModel model)
+    {
+        return new GridifyQueryModel
+        {
+            Page = 1,
+            PageSize = model.PageSize,
+            Filter = model.Filter
+        };
+    }
+}

src/GridifyExtensions/Models/CursoredResponse.cs

@@ -0,0 +1,3 @@
+namespace GridifyExtensions.Models;
+
+public record CursoredResponse<T>(List<T> Data, int PageSize);