Introduced sorting and paging options for queries

Author: johelvisguzman

src/DotNetToolkit.Repository/Queries/IQueryOptions.cs

@@ -0,0 +1,18 @@
+namespace DotNetToolkit.Repository.Queries
+{
+    using System.Linq;
+
+    /// <summary>
+    /// Represents a query options which can be used for sorting or paging on queries.
+    /// </summary>
+    /// <typeparam name="T">The entity type of the repository.</typeparam>
+    public interface IQueryOptions<T>
+    {
+        /// <summary>
+        /// Applies the current options to the specified query.
+        /// </summary>
+        /// <param name="query">The query.</param>
+        /// <returns>The new query with the defined options applied.</returns>
+        IQueryable<T> Apply(IQueryable<T> query);
+    }
+}

src/DotNetToolkit.Repository/Queries/PagingOptions.cs

@@ -0,0 +1,113 @@
+namespace DotNetToolkit.Repository.Queries
+{
+    using System;
+    using System.Linq;
+    using System.Linq.Expressions;
+
+    /// <summary>
+    /// Represents a paging option.
+    /// </summary>
+    /// <typeparam name="T">The entity type of the repository.</typeparam>
+    /// <typeparam name="TKey">The type of the property that is being sorted.</typeparam>
+    public class PagingOptions<T, TKey> : SortingOptions<T, TKey>
+    {
+        #region Fields
+
+        private const int DefaultPageSize = 100;
+        private int _pageIndex;
+        private int _pageSize;
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// Gets or sets the number of rows of the data page to retrieve.
+        /// </summary>
+        public int PageSize
+        {
+            get { return _pageSize; }
+            set
+            {
+                if (value <= 0)
+                    throw new ArgumentException($"{nameof(PageSize)} cannot be lower than zero.");
+
+                _pageSize = value;
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets the zero-based index of the data page to retrieve.
+        /// </summary>
+        public int PageIndex
+        {
+            get { return _pageIndex; }
+            set
+            {
+                if (value < 1)
+                    throw new ArgumentOutOfRangeException(nameof(PageIndex), "Cannot be lower than 1.");
+
+                _pageIndex = value;
+            }
+        }
+
+        /// <summary>
+        /// Gets the page count.
+        /// </summary>
+        public int PageCount { get; private set; }
+
+        #endregion
+
+        #region Constructors
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PagingOptions{TEntity, TKey}"/> class.
+        /// </summary>
+        /// <param name="pageIndex">The zero-based index of the data page to retrieve.</param>
+        /// <param name="sorting">The sorting expression.</param>
+        /// <param name="isDescending">if set to <c>true</c> use descending order; otherwise, use ascending.</param>
+        public PagingOptions(int pageIndex, Expression<Func<T, TKey>> sorting, bool isDescending = false) : base(sorting, isDescending)
+        {
+            PageIndex = pageIndex;
+            PageSize = DefaultPageSize;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PagingOptions{TEntity, TKey}"/> class.
+        /// </summary>
+        /// <param name="pageIndex">The zero-based index of the data page to retrieve.</param>
+        /// <param name="pageSize">The number of rows of the data page to retrieve.</param>
+        /// <param name="sorting">The sorting expression.</param>
+        /// <param name="isDescending">if set to <c>true</c> use descending order; otherwise, use ascending.</param>
+        public PagingOptions(int pageIndex, int pageSize, Expression<Func<T, TKey>> sorting, bool isDescending = false) : base(sorting, isDescending)
+        {
+            PageIndex = pageIndex;
+            PageSize = pageSize;
+        }
+
+        #endregion
+
+        #region Overrides of SortingOptions<TEntity,TKey>
+
+        /// <summary>
+        /// Applies the current options to the specified query.
+        /// </summary>
+        /// <param name="query">The query.</param>
+        /// <returns>The new query with the defined options applied.</returns>
+        public override IQueryable<T> Apply(IQueryable<T> query)
+        {
+            var pageCount = (int)Math.Ceiling(query.Count() / (decimal)PageSize);
+
+            if (PageIndex > pageCount)
+                throw new ArgumentOutOfRangeException(nameof(PageIndex), "Cannot be greater than the total number of pages.");
+
+            PageCount = pageCount;
+
+            query = base.Apply(query);
+
+            return query.Skip((PageIndex - 1) * PageSize).Take(PageSize);
+        }
+
+        #endregion
+    }
+}

src/DotNetToolkit.Repository/Queries/SortingOptions.cs

@@ -0,0 +1,69 @@
+namespace DotNetToolkit.Repository.Queries
+{
+    using System;
+    using System.Linq;
+    using System.Linq.Expressions;
+
+    /// <summary>
+    /// Represents a sorting option.
+    /// </summary>
+    /// <typeparam name="T">The entity type of the repository.</typeparam>
+    /// <typeparam name="TKey">The type of the property that is being sorted.</typeparam>
+    public class SortingOptions<T, TKey> : IQueryOptions<T>
+    {
+        #region Fields
+
+        private readonly Expression<Func<T, TKey>> _sorting;
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// Gets or sets a value indicating whether this sorting option is descending.
+        /// </summary>
+        /// <value>
+        /// <c>true</c> if this sorting option is descending; otherwise, <c>false</c>.
+        /// </value>
+        public bool IsDescending { get; set; }
+
+        #endregion
+
+        #region Constructors
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SortingOptions{TEntity, TKey}"/> class.
+        /// </summary>
+        /// <param name="sorting">The sorting expression.</param>
+        /// <param name="isDescending">if set to <c>true</c> use descending order; otherwise, use ascending.</param>
+        public SortingOptions(Expression<Func<T, TKey>> sorting, bool isDescending = false)
+        {
+            _sorting = sorting;
+
+            IsDescending = isDescending;
+        }
+
+        #endregion
+
+        #region Implementation of IQueryOptions<T>
+
+        /// <summary>
+        /// Applies the current options to the specified query.
+        /// </summary>
+        /// <param name="query">The query.</param>
+        /// <returns>The new query with the defined options applied.</returns>
+        public virtual IQueryable<T> Apply(IQueryable<T> query)
+        {
+            if (_sorting != null)
+            {
+                query = IsDescending
+                    ? query.OrderByDescending(_sorting)
+                    : query.OrderBy(_sorting);
+            }
+
+            return query;
+        }
+
+        #endregion
+    }
+}