Get JWT claims directly from the token, ASP Net Core 2.1

Here is a simple workaround:

    var tokenDescriptor = new SecurityTokenDescriptor
        {
            Expires = DateTime.UtcNow.AddHours(3),
            Subject = new ClaimsIdentity(new[]
            {
                new Claim(ClaimTypes.Name, "[email protected]"),
                new Claim(ClaimTypes.Email, "[email protected]")
            }),
            SigningCredentials = new SigningCredentials(key: new SymmetricSecurityKey(key), algorithm: SecurityAlgorithms.HmacSha256Signature)
        };

    var Securitytoken = new JwtSecurityTokenHandler().CreateToken(tokenDescriptor);
    var tokenstring = new JwtSecurityTokenHandler().WriteToken(Securitytoken);
    var token = new JwtSecurityTokenHandler().ReadJwtToken(tokenstring);
    var claim = token.Claims.First(c => c.Type == "email").Value;
    return claim;

For example in my current project I get claims by validation. Its refresh token, so I cant use [Authorize] attribute.

using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;

public ClaimsPrincipal ValidateRefreshToken(string refreshToken)
{
    try
    {
        var validationParams = new TokenValidationParameters
        {
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = new SymmetricSecurityKey(tokenSecurityKey),
            ValidateLifetime = true
        };
        return new JwtSecurityTokenHandler().ValidateToken
        (
            refreshToken, 
            validationParams, 
            out SecurityToken token
        );
    }
    catch (Exception e)
    {
        Log.Error(e.Message);
        return null;
    }
}

and then

var claims = ValidateRefreshToken(refreshToken);
...
var userIdString = claims.Claims.FirstOrDefault(x => x.Type == "userId")?.Value;