//--------------------------------------------------------------------- // // Copyright (c) Microsoft Corporation. All rights reserved. // // // @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; /// /// This class represents a query parameter at the object layer, which consists /// of a Name, a Type and a Value. /// public sealed class ObjectParameter { #region Static Methods // -------------- // Static Methods // -------------- #region ValidateParameterName /// /// 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 (_). /// 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) /// /// 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. /// /// /// The parameter name. /// /// /// The CLR type of the parameter. /// /// /// A new unbound ObjectParameter instance. /// /// /// If the value of either argument is null. /// /// /// 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 (_). /// 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) /// /// 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. /// /// /// The parameter name. /// /// /// The initial value (and inherently, type) of the parameter. /// /// /// A new fully-bound ObjectParameter instance. /// /// /// If the value of either argument is null. /// /// /// 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 (_). /// 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 // ------------------- /// /// This constructor is used by to create a new ObjectParameter /// with field values taken from the field values of an existing ObjectParameter. /// /// /// The existing ObjectParameter instance from which field values should be taken. /// /// /// A new ObjectParameter instance with the same field values as the specified ObjectParameter /// 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 // -------------- /// /// The name of the parameter. Cannot be null and is immutable. /// private string _name; /// /// The CLR type of the parameter. Cannot be null and is immutable. /// private Type _type; /// /// 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. /// private Type _mappableType; /// /// Used to specify the exact metadata type of this parameter. /// Typically null, can only be set using the internal property. /// private TypeUsage _effectiveType; /// /// The value of the parameter. Does not need to be bound until execution /// time and can be modified at any time. /// private object _value; #endregion #region Public Properties // ----------------- // Public Properties // ----------------- /// /// The parameter name, which can only be set through a constructor. /// public string Name { get { return this._name; } } /// /// The parameter type, which can only be set through a constructor. /// public Type ParameterType { get { return this._type; } } /// /// 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. /// public object Value { get { return this._value; } set { this._value = value; } } #endregion #region Internal Properties // ------------------- // Internal Properties // ------------------- /// /// Gets or sets a that specifies the exact /// type of which the parameter value is considered an instance. /// internal TypeUsage TypeUsage { get { return _effectiveType; } set { Debug.Assert(null == _effectiveType, "Effective type should only be set once"); _effectiveType = value; } } /// /// 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. /// internal Type MappableType { get { return this._mappableType; } } #endregion #region Internal Methods // ---------------- // Internal Methods // ---------------- /// /// Creates a new ObjectParameter instance with identical field values to this instance. /// /// The new ObjectParameter instance internal ObjectParameter ShallowCopy() { return new ObjectParameter(this); } /// /// 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. /// 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 } }