NH-3488 - alternate Linq DML syntax, inspired by linq2db.

Author: fredericDelaporte

src/NHibernate.Test/LinqBulkManipulation/Fixture.cs

@@ -11,40 +11,38 @@ namespace NHibernate.Linq
 	/// </summary>
 	/// <typeparam name="TSource">The type of the entity source of the insert or to update.</typeparam>
 	/// <typeparam name="TTarget">The type of the entity to insert or to update.</typeparam>
-	public class Assignments<TSource, TTarget>
+	internal class Assignments<TSource, TTarget>
 	{
 		private readonly Dictionary<string, Expression> _assignments = new Dictionary<string, Expression>();
 
 		internal IReadOnlyDictionary<string, Expression> List => _assignments;
 
 		/// <summary>
-		/// Sets the specified property.
+		/// Set the specified property.
 		/// </summary>
 		/// <typeparam name="TProp">The type of the property.</typeparam>
 		/// <param name="property">The property.</param>
 		/// <param name="expression">The expression that should be assigned to the property.</param>
 		/// <returns>The current assignments list.</returns>
-		public Assignments<TSource, TTarget> Set<TProp>(Expression<Func<TTarget, TProp>> property, Expression<Func<TSource, TProp>> expression)
+		public void Set<TProp>(Expression<Func<TTarget, TProp>> property, Expression<Func<TSource, TProp>> expression)
 		{
 			if (expression == null)
 				throw new ArgumentNullException(nameof(expression));
 			var member = GetMemberExpression(property);
 			_assignments.Add(member.GetMemberPath(), expression);
-			return this;
 		}
 
 		/// <summary>
-		/// Sets the specified property.
+		/// Set the specified property.
 		/// </summary>
 		/// <typeparam name="TProp">The type of the property.</typeparam>
 		/// <param name="property">The property.</param>
 		/// <param name="value">The value.</param>
 		/// <returns>The current assignments list.</returns>
-		public Assignments<TSource, TTarget> Set<TProp>(Expression<Func<TTarget, TProp>> property, TProp value)
+		public void Set<TProp>(Expression<Func<TTarget, TProp>> property, TProp value)
 		{
 			var member = GetMemberExpression(property);
 			_assignments.Add(member.GetMemberPath(), Expression.Constant(value, typeof(TProp)));
-			return this;
 		}
 
 		private static MemberExpression GetMemberExpression<TProp>(Expression<Func<TTarget, TProp>> property)

src/NHibernate/Linq/Assignments.cs

@@ -0,0 +1,146 @@
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace NHibernate.Linq
+{
+	/// <summary>
+	/// NHibernate LINQ DML extension methods. They are meant to work with <see cref="NhQueryable{T}"/>. Supplied <see cref="IQueryable{T}"/> parameters
+	/// should at least have an <see cref="INhQueryProvider"/> <see cref="IQueryable.Provider"/>. <see cref="LinqExtensionMethods.Query{T}(ISession)"/> and
+	/// its overloads supply such queryables.
+	/// </summary>
+	public static class DmlExtensionMethods
+	{
+		/// <summary>
+		/// Delete all entities selected by the specified query. The delete operation is performed in the database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to delete.</param>
+		/// <returns>The number of deleted entities.</returns>
+		public static int Delete<TSource>(this IQueryable<TSource> source)
+		{
+			var provider = source.GetNhProvider();
+			return provider.ExecuteDml<TSource>(QueryMode.Delete, source.Expression);
+		}
+
+		/// <summary>
+		/// Update all entities selected by the specified query. The update operation is performed in the database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <param name="expression">The update setters expressed as a member initialization of updated entities, e.g.
+		/// <c>x => new Dog { Name = x.Name, Age = x.Age + 5 }</c>. Unset members are ignored and left untouched.</param>
+		/// <returns>The number of updated entities.</returns>
+		public static int Update<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, TSource>> expression)
+		{
+			return ExecuteUpdate(source, DmlExpressionRewriter.PrepareExpression(source.Expression, expression), false);
+		}
+
+		/// <summary>
+		/// Update all entities selected by the specified query, using an anonymous initializer for specifying setters. The update operation is performed
+		/// in the database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <param name="expression">The assignments expressed as an anonymous object, e.g.
+		/// <c>x => new { Name = x.Name, Age = x.Age + 5 }</c>. Unset members are ignored and left untouched.</param>
+		/// <returns>The number of updated entities.</returns>
+		public static int Update<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, object>> expression)
+		{
+			return ExecuteUpdate(source, DmlExpressionRewriter.PrepareExpressionFromAnonymous(source.Expression, expression), false);
+		}
+
+		/// <summary>
+		/// Perform an <c>update versioned</c> on all entities selected by the specified query. The update operation is performed in the database without 
+		/// reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <param name="expression">The update setters expressed as a member initialization of updated entities, e.g.
+		/// <c>x => new Dog { Name = x.Name, Age = x.Age + 5 }</c>. Unset members are ignored and left untouched.</param>
+		/// <returns>The number of updated entities.</returns>
+		public static int UpdateVersioned<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, TSource>> expression)
+		{
+			return ExecuteUpdate(source, DmlExpressionRewriter.PrepareExpression(source.Expression, expression), true);
+		}
+
+		/// <summary>
+		/// Perform an <c>update versioned</c> on all entities selected by the specified query, using an anonymous initializer for specifying setters. 
+		/// The update operation is performed in the database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <param name="expression">The assignments expressed as an anonymous object, e.g.
+		/// <c>x => new { Name = x.Name, Age = x.Age + 5 }</c>. Unset members are ignored and left untouched.</param>
+		/// <returns>The number of updated entities.</returns>
+		public static int UpdateVersioned<TSource>(this IQueryable<TSource> source, Expression<Func<TSource, object>> expression)
+		{
+			return ExecuteUpdate(source, DmlExpressionRewriter.PrepareExpressionFromAnonymous(source.Expression, expression), true);
+		}
+
+		/// <summary>
+		/// Initiate an update for the entities selected by the query. Return
+		/// a builder allowing to set properties and allowing to execute the update.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <returns>An update builder.</returns>
+		public static UpdateBuilder<TSource> UpdateBuilder<TSource>(this IQueryable<TSource> source)
+		{
+			return new UpdateBuilder<TSource>(source);
+		}
+
+		internal static int ExecuteUpdate<TSource>(this IQueryable<TSource> source, Expression updateExpression, bool versioned)
+		{
+			var provider = source.GetNhProvider();
+			return provider.ExecuteDml<TSource>(versioned ? QueryMode.UpdateVersioned : QueryMode.Update, updateExpression);
+		}
+
+		/// <summary>
+		/// Insert all entities selected by the specified query. The insert operation is performed in the database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <typeparam name="TTarget">The type of the entities to insert.</typeparam>
+		/// <param name="source">The query matching entities source of the data to insert.</param>
+		/// <param name="expression">The expression projecting a source entity to the entity to insert.</param>
+		/// <returns>The number of inserted entities.</returns>
+		public static int InsertInto<TSource, TTarget>(this IQueryable<TSource> source, Expression<Func<TSource, TTarget>> expression)
+		{
+			return ExecuteInsert<TSource, TTarget>(source, DmlExpressionRewriter.PrepareExpression(source.Expression, expression));
+		}
+
+		/// <summary>
+		/// Insert all entities selected by the specified query, using an anonymous initializer for specifying setters. <typeparamref name="TTarget"/>
+		/// must be explicitly provided, e.g. <c>source.InsertInto&lt;Cat, Dog&gt;(c => new {...})</c>. The insert operation is performed in the
+		/// database without reading the entities out of it.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <typeparam name="TTarget">The type of the entities to insert. Must be explicitly provided.</typeparam>
+		/// <param name="source">The query matching entities source of the data to insert.</param>
+		/// <param name="expression">The expression projecting a source entity to an anonymous object representing 
+		/// the entity to insert.</param>
+		/// <returns>The number of inserted entities.</returns>
+		public static int InsertInto<TSource, TTarget>(this IQueryable<TSource> source, Expression<Func<TSource, object>> expression)
+		{
+			return ExecuteInsert<TSource, TTarget>(source, DmlExpressionRewriter.PrepareExpressionFromAnonymous(source.Expression, expression));
+		}
+
+		/// <summary>
+		/// Initiate an insert using selected entities as a source. Return
+		/// a builder allowing to set properties to insert and allowing to execute the update.
+		/// </summary>
+		/// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+		/// <param name="source">The query matching the entities to update.</param>
+		/// <returns>An update builder.</returns>
+		public static InsertBuilder<TSource> InsertBuilder<TSource>(this IQueryable<TSource> source)
+		{
+			return new InsertBuilder<TSource>(source);
+		}
+
+		internal static int ExecuteInsert<TSource, TTarget>(this IQueryable<TSource> source, Expression insertExpression)
+		{
+			var provider = source.GetNhProvider();
+			return provider.ExecuteDml<TTarget>(QueryMode.Insert, insertExpression);
+		}
+	}
+}

src/NHibernate/Linq/DmlExtensionMethods.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace NHibernate.Linq
+{
+	/// <summary>
+	/// An insert builder on which entities to insert can be specified.
+	/// </summary>
+	/// <typeparam name="TSource">The type of the entities selected as source of the insert.</typeparam>
+	public class InsertBuilder<TSource>
+	{
+		private readonly IQueryable<TSource> _source;
+
+		internal InsertBuilder(IQueryable<TSource> source)
+		{
+			_source = source;
+		}
+
+		/// <summary>
+		/// Specifies the type of the entities to insert, and return an insert builder allowing to specify the values to insert.
+		/// </summary>
+		/// <typeparam name="TTarget">The type of the entities to insert.</typeparam>
+		/// <returns>An insert builder.</returns>
+		public InsertBuilder<TSource, TTarget> Into<TTarget>()
+		{
+			return new InsertBuilder<TSource, TTarget>(_source);
+		}
+	}
+
+	/// <summary>
+	/// An insert builder on which entities to insert can be specified.
+	/// </summary>
+	/// <typeparam name="TSource">The type of the entities selected as source of the insert.</typeparam>
+	/// <typeparam name="TTarget">The type of the entities to insert.</typeparam>
+	public class InsertBuilder<TSource, TTarget>
+	{
+		private readonly IQueryable<TSource> _source;
+		private readonly Assignments<TSource, TTarget> _assignments = new Assignments<TSource, TTarget>();
+
+		internal InsertBuilder(IQueryable<TSource> source)
+		{
+			_source = source;
+		}
+
+		/// <summary>
+		/// Set the specified property value and return this builder.
+		/// </summary>
+		/// <typeparam name="TProp">The type of the property.</typeparam>
+		/// <param name="property">The property.</param>
+		/// <param name="expression">The expression that should be assigned to the property.</param>
+		/// <returns>This insert builder.</returns>
+		public InsertBuilder<TSource, TTarget> Value<TProp>(Expression<Func<TTarget, TProp>> property, Expression<Func<TSource, TProp>> expression)
+		{
+			_assignments.Set(property, expression);
+			return this;
+		}
+
+		/// <summary>
+		/// Set the specified property value and return this builder.
+		/// </summary>
+		/// <typeparam name="TProp">The type of the property.</typeparam>
+		/// <param name="property">The property.</param>
+		/// <param name="value">The value.</param>
+		/// <returns>This insert builder.</returns>
+		public InsertBuilder<TSource, TTarget> Value<TProp>(Expression<Func<TTarget, TProp>> property, TProp value)
+		{
+			_assignments.Set(property, value);
+			return this;
+		}
+
+		/// <summary>
+		/// Insert the entities. The insert operation is performed in the database without reading the entities out of it. Will use
+		/// <c>INSERT INTO [...] SELECT FROM [...]</c> in the database.
+		/// </summary>
+		/// <returns>The number of inserted entities.</returns>
+		public int Insert()
+		{
+			return _source.ExecuteInsert<TSource, TTarget>(DmlExpressionRewriter.PrepareExpression<TSource>(_source.Expression, _assignments.List));
+		}
+	}
+}