MethodExpression.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / Extensions / UI / WebControls / Expressions / MethodExpression.cs / 1305376 / MethodExpression.cs
                        
                        
                            #if ORYX_VNEXT 
namespace Microsoft.Web.Data.UI.WebControls.Expressions {
    using System.Web;
#else
namespace System.Web.UI.WebControls.Expressions { 
#endif
    using System; 
    using System.Collections.Generic; 
    using System.Collections.ObjectModel;
    using System.Globalization; 
    using System.Linq;
    using System.Linq.Expressions;
    using System.Reflection;
    using System.Web.Compilation; 
    using System.Web.DynamicData;
    using System.Web.Resources; 
    using System.Web.UI.WebControls; 

    public class MethodExpression : ParameterDataSourceExpression { 
        private static readonly BindingFlags MethodFlags = BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy;

        // We'll populate a list of ways to get the type
        private Func[] typeGetters; 

        public string TypeName { 
            get { 
                return (string)ViewState["TypeName"] ?? String.Empty;
            } 
            set {
                ViewState["TypeName"] = value;
            }
        } 

        public string MethodName { 
            get { 
                return (string)ViewState["MethodName"] ?? String.Empty;
            } 
            set {
                ViewState["MethodName"] = value;
            }
        } 

        public bool IgnoreIfNotFound { 
            get { 
                object o = ViewState["IgnoreIfNotFound"];
                return o != null ? (bool)o : false; 
            }
            set {
                ViewState["IgnoreIfNotFound"] = value;
            } 
        }
 
        public MethodExpression() { 
            // 1. If a TypeName is specified find the method on that type.
            // 2. Otherwise, if the DataSource is an IDynamicDataSource, then use context type and search for the method. 
            // 3. Otherwise look for the method on the current TemplateControl (Page/UserControl) etc.
            typeGetters = new Func[] {
                () => GetType(TypeName),
                () => GetType(DataSource), 
                () => (Owner != null && Owner.TemplateControl != null) ? Owner.TemplateControl.GetType() : null
            }; 
        } 

        private static Type GetType(string typeName) { 
            if (!String.IsNullOrEmpty(typeName)) {
                return BuildManager.GetType(typeName, false /* throwOnError */, true /* ignoreCase */);
            }
            return null; 
        }
 
        private static Type GetType(IQueryableDataSource dataSource) { 
            IDynamicDataSource dynamicDataSource = dataSource as IDynamicDataSource;
            if (dynamicDataSource != null) { 
                return dynamicDataSource.ContextType;
            }
            return null;
        } 

        internal MethodInfo ResolveMethod() { 
            if (String.IsNullOrEmpty(MethodName)) { 
                throw new InvalidOperationException(AtlasWeb.MethodExpression_MethodNameMustBeSpecified);
            } 

            MethodInfo methodInfo = null;
            // We allow the format string {0} in the method name
            IDynamicDataSource dataSource = DataSource as IDynamicDataSource; 
            if (dataSource != null) {
                MethodName = String.Format(CultureInfo.CurrentCulture, MethodName, dataSource.EntitySetName); 
            } 
            else if (MethodName.Contains("{0}")) {
                // If method has a format string but no IDynamicDataSource then throw an exception 
                throw new InvalidOperationException(AtlasWeb.MethodExpression_DataSourceMustBeIDynamicDataSource);
            }

            foreach (Func typeGetter in typeGetters) { 
                Type type = typeGetter();
                // If the type is null continue to next fall back function 
                if (type == null) { 
                    continue;
                } 

                methodInfo = type.GetMethod(MethodName, MethodFlags);
                if (methodInfo != null) {
                    break; 
                }
            } 
 
            return methodInfo;
        } 

        public override IQueryable GetQueryable(IQueryable source) {
            if (source == null) {
                throw new ArgumentNullException("source"); 
            }
 
            MethodInfo method = ResolveMethod(); 

            // Get the parameter values 
            IDictionary parameterValues = GetValues();

            if (method == null) {
                if (IgnoreIfNotFound) { 
                    // Unchange the IQueryable if the user set IgnoreIfNotFound
                    return source; 
                } 
                throw new InvalidOperationException(String.Format(CultureInfo.InvariantCulture,
                    AtlasWeb.MethodExpression_MethodNotFound, MethodName)); 
            }

            if(!method.IsStatic) {
                throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, 
                    AtlasWeb.MethodExpression_MethodMustBeStatic, MethodName));
            } 
 
            ParameterInfo[] parameterArray = method.GetParameters();
            if (parameterArray.Length == 0 || !parameterArray[0].ParameterType.IsAssignableFrom(source.GetType())) { 
                throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, AtlasWeb.MethodExpression_FirstParamterMustBeCorrectType,
                    MethodName, source.GetType()));
            }
 
            object[] arguments = new object[parameterArray.Length];
            // First argument is the IQueryable 
            arguments[0] = source; 
            for (int i = 1; i < parameterArray.Length; ++i) {
                ParameterInfo param = parameterArray[i]; 
                object value;
                if (!parameterValues.TryGetValue(param.Name, out value)) {
                    throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture,
                        AtlasWeb.MethodExpression_ParameterNotFound, MethodName, param.Name)); 
                }
 
                arguments[i] = DataSourceHelper.BuildObjectValue(value, param.ParameterType, param.Name); 
            }
 
            object result = method.Invoke(null, arguments);

            // Require the return type be the same as the parameter type
            if (result != null) { 
                IQueryable queryable = result as IQueryable;
                // Check if the user did a projection (changed the T in IQuerable) 
                if (queryable == null || !queryable.ElementType.IsAssignableFrom(source.ElementType)) { 
                    throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, AtlasWeb.MethodExpression_ChangingTheReturnTypeIsNotAllowed,
                                                        source.ElementType.FullName)); 
                }
            }

            return (IQueryable)result; 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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MethodExpression.cs source code in C# .NET

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