To add an appsettings.json file to a C# console app:
Step 1. Add the "Microsoft.Extensions.Configuration.Json" package to the project.
Adding this package also pulls in the "Microsoft.Extensions.Configuration.Abstractions" and "Microsoft.Extensions.Primitives" packages (as of June 2022).
Step 2. Add a appsettings.json file to the root of the project.
Step 3. Right-click the appsettings.json file to show its Properties window. Then set its "Copy to Output Directory" property to "Copy always." This ensures the appsettings.json file is copied to the Debug or Release folder every time the project is built.
Figure 1. Set "Copy to Output Directory" property
Step 4. Add values to the appsettings.json file. The example below shows a couple of connection strings defined in the appsettings.json file.
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{ "ConnectionString": { "SqlServer": "Data Source=.;Initial Catalog=Crm;Integrated Security=True", "Sqlite": "Data Source=C:\\Users\\thumb\\Documents\\db\\ProjectDiaryDB.db" } } |
Step 5. Add this using statement to your project:
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using Microsoft.Extensions.Configuration; |
Step 6. Add this bootstrap code to instance an IConfiguration object:
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var builder = new ConfigurationBuilder(); builder.SetBasePath(Directory.GetCurrentDirectory()) .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true); IConfiguration config = builder.Build(); |
You can park this code away in a secondary class or use it inline. The resulting config object can then passed around to provide access to configuration values.
Step 7. Fetch values from the appsettings.json file:
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string connectionString = config["ConnectionString:SqlServer"]; |
or
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string connectionString = config.GetSection("ConnectionString").GetSection("SqlServer").Value; |
Surprisingly, the keys to the values in the appsettings.json file are not case-sensitive with either technique above. However, it seems prudent to me to treat them as such.
Configuration flexibility
Using an appsettings.json file with the IConfiguration object offers lots of flexibility. For example, the configuration below:
- Reads values from
appsettings.jsonfirst - Then if it is present, reads any values from
appsettings.dev.json, overwriting, or adding to, values read fromappsettings.json - Then, attempt to read values from environmental settings. These also overwrite or add to, the setting values previously established with the first two steps.
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builder.SetBasePath(Directory.GetCurrentDirectory()) .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true); .AddJsonFile("appsettings.dev.json", optional: true, reloadOnChange: true) .AddEnvironmentVariables(); |
The package should be Microsoft.Extensions.Configuration.Json
and I don’t know why you wouldn’t use config.GetConnectionString(“SqlServer”)
Exactly, but then you would need to use the key “ConnectionStrings” (plural).
when I have both the appsettings.json and appsettings.dev.json it always reads both regardless of if I have done a Release or Debug run in Visual Studio. How do I get it to only include reading the .dev.json file in Debug mode?
On .Net Core 7 you need to add the Nuget
Microsoft.Extensions.Configuration.FileExtensions