Enhance Param validation and refactor AddParam methods

Updated the `Param` struct to include validation for the `name` parameter, ensuring it is not null or whitespace. The `Value` property is now conditionally set based on the `direction` parameter.

Refactored multiple overloads of the `AddParam` method to utilize a new `AddParam(Param param)` method, reducing code duplication and improving maintainability. The `AddReturnParam` methods were also updated to leverage this new method for consistency.

Author: electricessence

Source/Core/ExpressiveCommandBase.Param.cs

@@ -11,18 +11,29 @@ public abstract partial class ExpressiveCommandBase<TConnection, TCommand, TRead
 	/// A struct that represents the param to be created when the command is executed.
 	/// TDbType facilitates the difference between DbType and SqlDbType.
 	/// </summary>
-	public readonly record struct Param : IEquatable<Param>
+	public readonly record struct Param
 
 	{
 		/// <summary>
 		/// Constructs a <see cref="Param"/>.
 		/// </summary>
-		public Param(string name, object? value, TDbType? type = null, ParameterDirection direction = ParameterDirection.Input)
+		public Param(
+			string name,
+			object? value,
+			TDbType? type = null,
+			ParameterDirection direction = ParameterDirection.Input)
 		{
+			if (name is null) throw new ArgumentNullException(nameof(name));
+			if (string.IsNullOrWhiteSpace(name))
+				throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
+			Contract.EndContractBlock();
+
 			Name = name;
-			Value = value;
 			Type = type;
 			Direction = direction;
+
+			bool isInput = direction is ParameterDirection.Input or ParameterDirection.InputOutput;
+			Value = isInput ? (value ?? DBNull.Value) : value;
 		}
 
 		/// <summary>

Source/Core/ExpressiveCommandBase.cs

@@ -180,6 +180,15 @@ public TThis UseCancellationToken(CancellationToken token)
 
 	#region AddParam
 
+	/// <summary>
+	/// Shortcut to add a parameter to the params list.
+	/// </summary>
+	protected TThis AddParam(Param param)
+	{
+		Params.Add(param);
+		return (TThis)this;
+	}
+
 	/// <summary>
 	/// Adds a parameter to the params list.
 	/// </summary>
@@ -191,103 +200,39 @@ public TThis UseCancellationToken(CancellationToken token)
 	/// <exception cref="ArgumentNullException"><paramref name="name"/> is null.</exception>
 	/// <exception cref="ArgumentException"><paramref name="name"/> is blank.</exception>
 	public TThis AddParam(string name, object value, TDbType type, ParameterDirection direction = ParameterDirection.Input)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, value, type, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, value, type, direction));
 
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddParam(string name, object? value, ParameterDirection direction = ParameterDirection.Input)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, value ?? DBNull.Value, null, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, value, null, direction));
 
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddParam<T>(string name, T? value, TDbType? type = null, ParameterDirection direction = ParameterDirection.Input)
 		where T : struct
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, value ?? (object)DBNull.Value, type, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, value, type, direction));
 
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddParam(string name, string? value, TDbType? type = null, ParameterDirection direction = ParameterDirection.Input)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, value ?? (object)DBNull.Value, type, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, value, type, direction));
 
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddParam(string name, TDbType type, ParameterDirection direction = ParameterDirection.Input)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new (name, null, type, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, null, type, direction));
 
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddParam(string name, ParameterDirection direction = ParameterDirection.Input)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, null, null, direction));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, null, null, direction));
 
 	/// <summary>
 	/// Adds a return parameter to the params list.
 	/// </summary>
 	/// <inheritdoc cref="AddParam(string, object, TDbType, ParameterDirection)"/>
 	public TThis AddReturnParam(string name, TDbType type)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, null, type, ParameterDirection.ReturnValue));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, null, type, ParameterDirection.ReturnValue));
 
 	/// <inheritdoc cref="AddReturnParam(string, TDbType)"/>
 	public TThis AddReturnParam(string name)
-	{
-		if (name is null) throw new ArgumentNullException(nameof(name));
-		if (string.IsNullOrWhiteSpace(name))
-			throw new ArgumentException("Parameter names cannot be empty or white space.", nameof(name));
-		Contract.EndContractBlock();
-
-		Params.Add(new(name, null, null, ParameterDirection.ReturnValue));
-		return (TThis)this;
-	}
+		=> AddParam(new(name, null, null, ParameterDirection.ReturnValue));
 
 	/// <summary>
 	/// Conditionally adds a parameter to the params list.