Added GetWithCount method

Author: DanielW093

Postgrest/Interfaces/IPostgrestTable.cs

@@ -119,6 +119,15 @@ IPostgrestTable<TModel> Filter<TCriterion>(Expression<Func<TModel, object>> pred
         /// <returns></returns>
         Task<ModeledResponse<TModel>> Get(CancellationToken cancellationToken = default);
 
+        /// <summary>
+        /// Executes the query using the defined filters on the current instance, along with count from the specified query.
+        /// </summary>
+        /// <param name="type">The kind of count.</param>
+        /// <param name="cancellationToken"></param>
+        /// <returns></returns>
+        Task<Tuple<List<TModel>, int>> GetWithCount(Constants.CountType type,
+            CancellationToken cancellationToken = default);
+
         /// <summary>
         /// Executes a BULK INSERT query using the defined query params on the current instance.
         /// </summary>

Postgrest/Table.cs

@@ -634,6 +634,26 @@ public Task<ModeledResponse<TModel>> Get(CancellationToken cancellationToken = d
             Clear();
             return request;
         }
+        
+        /// <inheritdoc />
+        public async Task<Tuple<List<TModel>, int>> GetWithCount(CountType type, CancellationToken cancellationToken = default)
+        {
+            var attr = type.GetAttribute<MapToAttribute>();
+            
+            var headers = new Dictionary<string, string>
+            {
+                { "Prefer", $"count={attr?.Mapping}" }
+            };
+            
+            var request = Send<TModel>(_method, null, headers, cancellationToken);
+            Clear();
+            
+            var response = await request;
+            var countStr = response.ResponseMessage?.Content.Headers.GetValues("Content-Range").FirstOrDefault();
+            var count = int.Parse(countStr?.Split('/')[1] ?? throw new InvalidOperationException());
+
+            return new Tuple<List<TModel>, int>(response.Models, count);
+        }
 
         /// <summary>
         /// Generates the encoded URL with defined query parameters that will be sent to the Postgrest API.