How to always perform a function, regardless of the API route called? - asp.net-core-2.0

Question

I am creating a NetCore 2 API and connecting to a SQL Server Database. Is it possible to always call a function no matter what the route is? My example:
For each call I am passing in the necessary parameters to connect to the SQL DB inside the headers. I am going to have hundreds of calls in this api, so I really don't want to duplicate this for every single call:
[HttpGet]
public async Task<IEnumerable<DEPARTMENT>> Get(
[FromHeader] string Server,
[FromHeader] string Database,
[FromHeader] string Username,
[FromHeader] string Password,
[FromHeader] string Trusted)
{
util.SetConnectionString(Server, Database, Username, Password, Trusted);
return await this.departmentDataProvider.GetDepartments();
}
[HttpGet("{DepartmentId}")]
public async Task<IEnumerable<DEPARTMENT>> Get(
string DepartmentId,
[FromHeader] string Server,
[FromHeader] string Database,
[FromHeader] string Username,
[FromHeader] string Password,
[FromHeader] string Trusted)
{
util.SetConnectionString(Server, Database, Username, Password, Trusted);
return await this.departmentDataProvider.GetDepartment(DepartmentId);
}
I would like to create an ancestor function that just has the header connection parameters, and the call to set the connection string. End goal would be something like this:
Ancestor:
[HttpGet]
public async Task<IEnumerable<?>> Get(
[FromHeader] string Server,
[FromHeader] string Database,
[FromHeader] string Username,
[FromHeader] string Password,
[FromHeader] string Trusted)
{
util.SetConnectionString(Server, Database, Username, Password, Trusted);
}
Children:
[HttpGet]
public async Task<IEnumerable<DEPARTMENT>> Get()
{
return await this.departmentDataProvider.GetDepartments();
}
[HttpGet("{DepartmentId}")]
public async Task<IEnumerable<DEPARTMENT>> Get(string DepartmentId)
{
return await this.departmentDataProvider.GetDepartment(DepartmentId);
}
Edit:
Adding Util.cs & DepartmentDataProvider.cs for more information.
Util.cs
public static class util
{
public static string ConnectionString { get; set; }
public static void SetConnectionString(string Server, string Database, string UserName, string Password, string Trusted)
{
if (Trusted == "true")
ConnectionString = "Server=" + Server + ";Database=" + Database + ";Trusted_Connection=True;";
else
ConnectionString = "Server=" + Server + ";Database=" + Database + ";User ID= " + UserName + ";Password=" + Password + ";Trusted_Connection=False;";
}
public static string GetConnectionString()
{
return ConnectionString;
}
}
DepartmentDataProvider.cs
public class DepartmentDataProvider : IDepartmentDataProvider
{
public async Task<DEPARTMENT> GetDepartment(int DepartmentId)
{
string connString = util.GetConnectionString();
using (var sqlConnection = new SqlConnection(util.GetConnectionString()))
{
await sqlConnection.OpenAsync();
var dynamicParameters = new DynamicParameters();
dynamicParameters.Add("#DepartmentID", DepartmentId);
return await sqlConnection.QuerySingleOrDefaultAsync<DEPARTMENT>(
"Select * From DEPARTMENT Where DEPARTMENT_ID = #DepartmentID",
dynamicParameters,
commandType: CommandType.Text);
}
}
}

Answer 1

Create a class to encapsulate the connection string data into which any relevant objects will be injected (e.g. maybe the HttpContext):
public class ConnectingStringParmsFromHeaders
{
public string Server { get; private set; }
// other properties
// ideally you wouldn't depend on ASP.NET Core constructs such as HttContext
// but I'm using it here for brevity
public ConnectionStringPropertiesFromHeaders( HttpContext httpContext )
{
ReadPropertiesFromHeaders( httpContext.Request.Headers );
}
private void ReadPropertiesFromHeaders( IHeaderDictionary headers )
{
// do your header-reading thing here
}
public string BuildConnectionString()
{
// your Util.SetConnectionString(...) code here
// using local instance properties and not static properties
}
}
Next, register this class with lifetime of Scoped (single object reused during the same HTTP request):
public void ConfigureServices(IServiceCollection services)
{
...
services.AddScoped<ConnectionStringParmsFromHeaders>();
}
Finally, add a parameter of this type to your controllers' constructors and set a property or field for use in action methods:
public class DepartmentsController : Controller
{
private ConnectionStringParmsFromHeaders ConnStrParms { get; private set; }
public DepartmentsController( ConnectionStringParmsFromHeaders connStrParms )
{
ConnStrParms = connStrParms;
}
public async Task<IActionResult> Get()
{
// for illustrative purposes
var connStr = connStrParms.BuildConnectionString();
// remainder of your action method's code
}
}
Note that your Util class setting a static property with per-http-request header data is a problem b/c there can be multiple concurrent threads reading and writing with that same property and different data - you'll have no idea if you're using the correct data! Move the connection string generating code to this new config class so that you can access it on a per-request basis as shown in above's code sample.
The above code may not be 100% accurate as I can't test it right now but it should be enough to get you where you need to go.