//---------------------------------------------------------------------
// <copyright file="ObjectParameter.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupowner Microsoft
//---------------------------------------------------------------------
namespace System.Data.Objects
{
using System;
using System.Data;
using System.Data.Common.CommandTrees;
using System.Data.Metadata.Edm;
using System.Diagnostics;
/// <summary>
/// This class represents a query parameter at the object layer, which consists
/// of a Name, a Type and a Value.
/// </summary>
public sealed class ObjectParameter
{
#region Static Methods
// --------------
// Static Methods
// --------------
#region ValidateParameterName
/// <summary>
/// This internal method uses regular expression matching to ensure that the
/// specified parameter name is valid. Parameter names must start with a letter,
/// and may only contain letters (A-Z, a-z), numbers (0-9) and underscores (_).
/// </summary>
internal static bool ValidateParameterName (string name)
{
// Note: Parameter names must begin with a letter, and may contain only
// letters, numbers and underscores.
return DbCommandTree.IsValidParameterName(name);
}
#endregion
#endregion
#region Public Constructors
// -------------------
// Public Constructors
// -------------------
#region ObjectParameter (string, Type)
/// <summary>
/// This constructor creates an unbound (i.e., value-less) parameter from the
/// specified name and type. The value can be set at any time through the
/// public 'Value' property.
/// </summary>
/// <param name="name">
/// The parameter name.
/// </param>
/// <param name="type">
/// The CLR type of the parameter.
/// </param>
/// <returns>
/// A new unbound ObjectParameter instance.
/// </returns>
/// <exception cref="ArgumentNullException">
/// If the value of either argument is null.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// If the value of the name argument is invalid. Parameter names must start
/// with a letter and may only contain letters (A-Z, a-z), numbers (0-9) and
/// underscores (_).
/// </exception>
public ObjectParameter (string name, Type type)
{
EntityUtil.CheckArgumentNull(name, "name");
EntityUtil.CheckArgumentNull(type, "type");
if (!ObjectParameter.ValidateParameterName(name))
{
throw EntityUtil.Argument(System.Data.Entity.Strings.ObjectParameter_InvalidParameterName(name), "name");
}
this._name = name;
this._type = type;
// If the parameter type is Nullable<>, we need to extract out the underlying
// Nullable<> type argument.
this._mappableType = System.Data.Objects.ELinq.TypeSystem.GetNonNullableType(this._type);
}
#endregion
#region ObjectParameter (string, object)
/// <summary>
/// This constructor creates a fully-bound (i.e., valued) parameter from the
/// specified name and value. The type is inferred from the initial value, but
/// the value can be changed at any time through the public 'Value' property.
/// </summary>
/// <param name="name">
/// The parameter name.
/// </param>
/// <param name="value">
/// The initial value (and inherently, type) of the parameter.
/// </param>
/// <returns>
/// A new fully-bound ObjectParameter instance.
/// </returns>
/// <exception cref="ArgumentNullException">
/// If the value of either argument is null.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// If the value of the name argument is invalid. Parameter names must start
/// with a letter and may only contain letters (A-Z, a-z), numbers (0-9) and
/// underscores (_).
/// </exception>
public ObjectParameter (string name, object value)
{
EntityUtil.CheckArgumentNull(name, "name");
EntityUtil.CheckArgumentNull(value, "value");
if (!ObjectParameter.ValidateParameterName(name))
{
throw EntityUtil.Argument(System.Data.Entity.Strings.ObjectParameter_InvalidParameterName(name), "name");
}
this._name = name;
this._type = value.GetType();
this._value = value;
// If the parameter type is Nullable<>, we need to extract out the underlying
// Nullable<> type argument.
this._mappableType = System.Data.Objects.ELinq.TypeSystem.GetNonNullableType(this._type);
}
#endregion
#endregion
#region Private Constructors
// -------------------
// Copy Constructor
// -------------------
/// <summary>
/// This constructor is used by <see cref="ShallowCopy"/> to create a new ObjectParameter
/// with field values taken from the field values of an existing ObjectParameter.
/// </summary>
/// <param name="template">
/// The existing ObjectParameter instance from which field values should be taken.
/// </param>
/// <returns>
/// A new ObjectParameter instance with the same field values as the specified ObjectParameter
/// </returns>
private ObjectParameter(ObjectParameter template)
{
Debug.Assert(template != null, "Template ObjectParameter cannot be null");
this._name = template._name;
this._type = template._type;
this._mappableType = template._mappableType;
this._effectiveType = template._effectiveType;
this._value = template._value;
}
#endregion
#region Private Fields
// --------------
// Private Fields
// --------------
/// <summary>
/// The name of the parameter. Cannot be null and is immutable.
/// </summary>
private string _name;
/// <summary>
/// The CLR type of the parameter. Cannot be null and is immutable.
/// </summary>
private Type _type;
/// <summary>
/// The mappable CLR type of the parameter. Unless the parameter type is
/// Nullable, this type is equal to the parameter type. In the case of
/// Nullable parameters, this type is the underlying Nullable argument
/// type. Cannot be null and is immutable.
/// </summary>
private Type _mappableType;
/// <summary>
/// Used to specify the exact metadata type of this parameter.
/// Typically null, can only be set using the internal <see cref="TypeUsage"/> property.
/// </summary>
private TypeUsage _effectiveType;
/// <summary>
/// The value of the parameter. Does not need to be bound until execution
/// time and can be modified at any time.
/// </summary>
private object _value;
#endregion
#region Public Properties
// -----------------
// Public Properties
// -----------------
/// <summary>
/// The parameter name, which can only be set through a constructor.
/// </summary>
public string Name
{
get
{
return this._name;
}
}
/// <summary>
/// The parameter type, which can only be set through a constructor.
/// </summary>
public Type ParameterType
{
get
{
return this._type;
}
}
/// <summary>
/// The parameter value, which can be set at any time (and subsequently
/// changed) before query execution. Note that type-checking is not
/// enforced between the declared parameter type and the type of the
/// specified value; such validation is left up to the underlying
/// provider(s) at execution time.
/// </summary>
public object Value
{
get
{
return this._value;
}
set
{
this._value = value;
}
}
#endregion
#region Internal Properties
// -------------------
// Internal Properties
// -------------------
/// <summary>
/// Gets or sets a <see cref="TypeUsage"/> that specifies the exact
/// type of which the parameter value is considered an instance.
/// </summary>
internal TypeUsage TypeUsage
{
get
{
return _effectiveType;
}
set
{
Debug.Assert(null == _effectiveType, "Effective type should only be set once");
_effectiveType = value;
}
}
/// <summary>
/// The mappable parameter type; this is primarily used to handle the case of
/// Nullable parameter types. For example, metadata knows nothing about 'int?',
/// only 'Int32'. For internal use only.
/// </summary>
internal Type MappableType
{
get
{
return this._mappableType;
}
}
#endregion
#region Internal Methods
// ----------------
// Internal Methods
// ----------------
/// <summary>
/// Creates a new ObjectParameter instance with identical field values to this instance.
/// </summary>
/// <returns>The new ObjectParameter instance</returns>
internal ObjectParameter ShallowCopy()
{
return new ObjectParameter(this);
}
/// <summary>
/// This internal method ensures that the specified type is a scalar
/// type supported by the underlying provider by ensuring that scalar
/// metadata for this type is retrievable.
/// </summary>
internal bool ValidateParameterType (ClrPerspective perspective)
{
TypeUsage type = null;
// The parameter type metadata is only valid if it's scalar or enumeration type metadata.
if ((perspective.TryGetType(this._mappableType, out type)) &&
(TypeSemantics.IsScalarType(type)))
{
return true;
}
return false;
}
#endregion
}
}