ASP.NET Core appsettings.json update in code
Basically you can set the values in IConfiguration
like this:
IConfiguration configuration = ...
// ...
configuration["key"] = "value";
The issue there is that e.g. the JsonConfigurationProvider
does not implement the saving of the configuration into the file. As you can see in the source it does not override the Set method of ConfigurationProvider
. (see source)
You can create your own provider and implement the saving there. Here (Basic sample of Entity Framework custom provider) is an example how to do it.
Here is a relevant article from Microsoft regarding Configuration setup in .Net Core Apps:
Asp.Net Core Configuration
The page also has sample code which may also be helpful.
Update
I thought In-memory provider and binding to a POCO class might be of some use but does not work as OP expected.
The next option can be setting reloadOnChange
parameter of AddJsonFile to true while adding the configuration file and
manually parsing the JSON configuration file and making changes as intended.
public class Startup
{
...
public Startup(IHostingEnvironment env)
{
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
.AddEnvironmentVariables();
Configuration = builder.Build();
}
...
}
...
reloadOnChange
is only supported in ASP.NET Core 1.1 and higher.
I took Qamar Zamans code (thank you) and modified it to allow for editing parameters which are more:than:one:layer:deep.
Hope it helps someone out, surprised that this isn't a library feature somewhere.
public static class SettingsHelpers
{
public static void AddOrUpdateAppSetting<T>(string sectionPathKey, T value)
{
try
{
var filePath = Path.Combine(AppContext.BaseDirectory, "appsettings.json");
string json = File.ReadAllText(filePath);
dynamic jsonObj = Newtonsoft.Json.JsonConvert.DeserializeObject(json);
SetValueRecursively(sectionPathKey, jsonObj, value);
string output = Newtonsoft.Json.JsonConvert.SerializeObject(jsonObj, Newtonsoft.Json.Formatting.Indented);
File.WriteAllText(filePath, output);
}
catch (Exception ex)
{
Console.WriteLine("Error writing app settings | {0}", ex.Message);
}
}
private static void SetValueRecursively<T>(string sectionPathKey, dynamic jsonObj, T value)
{
// split the string at the first ':' character
var remainingSections = sectionPathKey.Split(":", 2);
var currentSection = remainingSections[0];
if (remainingSections.Length > 1)
{
// continue with the procress, moving down the tree
var nextSection = remainingSections[1];
SetValueRecursively(nextSection, jsonObj[currentSection], value);
}
else
{
// we've got to the end of the tree, set the value
jsonObj[currentSection] = value;
}
}
Update appsettings.json
file in ASP.NET Core at runtime.
Take this sample appsettings.json
file:
{
Config: {
IsConfig: false
}
}
This is the code to update IsConfig
property to true:
Main()
{
AddOrUpdateAppSetting("Config:IsConfig", true);
}
public static void AddOrUpdateAppSetting<T>(string key, T value)
{
try
{
var filePath = Path.Combine(AppContext.BaseDirectory, "appSettings.json");
string json = File.ReadAllText(filePath);
dynamic jsonObj = Newtonsoft.Json.JsonConvert.DeserializeObject(json);
var sectionPath = key.Split(":")[0];
if (!string.IsNullOrEmpty(sectionPath))
{
var keyPath = key.Split(":")[1];
jsonObj[sectionPath][keyPath] = value;
}
else
{
jsonObj[sectionPath] = value; // if no sectionpath just set the value
}
string output = Newtonsoft.Json.JsonConvert.SerializeObject(jsonObj, Newtonsoft.Json.Formatting.Indented);
File.WriteAllText(filePath, output);
}
catch (ConfigurationErrorsException)
{
Console.WriteLine("Error writing app settings");
}
}