ConfigurationManager.AppSettings.Settings.Add（）在每次运行时附加值 [英] ConfigurationManager.AppSettings.Settings.Add() appends value on each run

问题描述

我有以下代码。每次运行C＃项目时，都会附加应用设置键的值。

I have the following piece of code. Every time, I run the C# project the values for the app settings key gets appended.

var configSettings = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
configSettings.AppSettings.Settings.Add("Key", "Value");
configSettings.Save(ConfigurationSaveMode.Full, true);
ConfigurationManager.RefreshSection("appSettings");

第一次运行：
键：值

1st run: Key: Value

第二次运行：
键，值，值

2nd run: Key, Value, Value

为什么要附加值？每次运行时，我都需要从干净的盘子开始。

Why are the values getting appended? I need it to start on a clean plate on each run.

推荐答案

您需要检查AppSetting是否已经存在。如果存在，则必须更新该值。

You need to check if the AppSetting already exists. If it exists, you have to update the value. If it doesn't you have to add the value.

var configSettings = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var settings = configSettings.AppSettings.Settings;
if (settings["Key"] == null)
{
    settings.Add("Key", "Value");
}
else
{
    settings["Key"].Value = "NewValue";
}
configSettings.Save(ConfigurationSaveMode.Full, true);
ConfigurationManager.RefreshSection("appSettings");

AppSettings.Settings 基本上是键/值对。

查看以下MSDN文档以获取更多详细信息。

Check the below MSDN documentation for more details.

https://msdn.microsoft.com/zh-我们/库/system.configuration.configurationmanager.appsettings(v=vs.110).aspx

https://msdn.microsoft.com/zh-CN/library/system .configuration.appsettingssection.settings（v = vs.110）.aspx

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