CODEWITHSUNDEEP
c#asp.net-core
Jenni
Jenni

Reputation: 95

How to use IOptions<T> as a generic parameter in a generic method

I am trying to create a generic method that use IOptions<T> as parameter but the code seems to be invalid.

Visual studio displays the following message:

TConfig must be a non-abstract type with a non-parameterless constructor in order to use it as a parameter 'TOption' in the generic type or method 'IOptions<TOptions>'

Any suggestion on how to fix this would be appreciated. Thanks!!

public static IServiceCollection AddConfigurations<TConfig>(
    this IServiceCollection services, IConfiguration configuration, 
    IOptions<TConfig> options) 
    where TConfig : class
{
}

Upvotes: 2

Views: 5778

Answers (2)

Christian Gollhardt
Christian Gollhardt

Reputation: 17024

The problem is, that IOptions has the following contraint:

where TOptions : class, new()

So you need this constraint (new()) too:

public static IServiceCollection AddConfigurations<TConfig>(
    this IServiceCollection services, IConfiguration configuration, 
    IOptions<TConfig> options) 
    where TConfig : class, new()
{
}

Upvotes: 7

D Stanley
D Stanley

Reputation: 152626

Look at the constraints on T in the definition of IOptions<T>. The constraints on AddConfigurations<TConfig> need to have at least those restrictions on TConfig since it uses IOptions<TConfig>.

Upvotes: 1

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