AppSettingsExpressionBuilder.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / Compilation / AppSettingsExpressionBuilder.cs / 1 / AppSettingsExpressionBuilder.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.Compilation { 
    using System; 
    using System.Security.Permissions;
    using System.CodeDom; 
    using System.ComponentModel;
    using System.Configuration;
    using System.Diagnostics;
    using System.Web.UI; 

 
    [ExpressionPrefix("AppSettings")] 
    [ExpressionEditor("System.Web.UI.Design.AppSettingsExpressionEditor, " + AssemblyRef.SystemDesign)]
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)] 
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
    public class AppSettingsExpressionBuilder : ExpressionBuilder {
        public override bool SupportsEvaluate {
            get { 
                return true;
            } 
        } 

 
        public override CodeExpression GetCodeExpression(BoundPropertyEntry entry,
            object parsedData, ExpressionBuilderContext context) {

            if (entry.DeclaringType == null || entry.PropertyInfo == null) { 
                return new CodeMethodInvokeExpression(
                    new CodeTypeReferenceExpression(this.GetType()), 
                    "GetAppSetting", 
                    new CodePrimitiveExpression(entry.Expression.Trim()));
            } 
            else {
                return new CodeMethodInvokeExpression(
                    new CodeTypeReferenceExpression(this.GetType()),
                    "GetAppSetting", 
                    new CodePrimitiveExpression(entry.Expression.Trim()),
                    new CodeTypeOfExpression(entry.DeclaringType), 
                    new CodePrimitiveExpression(entry.PropertyInfo.Name)); 
            }
        } 

        public override object EvaluateExpression(object target, BoundPropertyEntry entry,
            object parsedData, ExpressionBuilderContext context) {
 
            return GetAppSetting(entry.Expression, target.GetType(), entry.PropertyInfo.Name);
        } 
 
        public static object GetAppSetting(string key) {
            string value = ConfigurationManager.AppSettings[key]; 

            if (value == null) {
                throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_found, key));
            } 
            return value;
        } 
 
        public static object GetAppSetting(string key, Type targetType, string propertyName) {
            string value = ConfigurationManager.AppSettings[key]; 

            if (targetType != null) {
                PropertyDescriptor propDesc = TypeDescriptor.GetProperties(targetType)[propertyName];
                if (propDesc != null) { 
                    if (propDesc.PropertyType != typeof(string)) {
                        TypeConverter converter = propDesc.Converter; 
                        if (converter.CanConvertFrom(typeof(string))) { 
                            return converter.ConvertFrom(value);
                        } 
                        else {
                            throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_convertible, value, propDesc.PropertyType.Name, propDesc.Name));
                        }
                    } 
                }
            } 
 
            if (value == null) {
                throw new InvalidOperationException(SR.GetString(SR.AppSetting_not_found, key)); 
            }
            return value;
        }
    } 
}

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