Cannot convert type 'System.Threading.Tasks.Task<System.Data.Common.DbDataReader>' to 'System.Threading.Tasks.Task<System.Data.IDataReader>'

Question

I am facing couple of issues with the following code in C#.

1. I have an asynchronous method that executes a SQL query and returns a Task, but it gives a compile-time error when trying to return the result of another asynchronous method call that returns a Task<System.Data.Common.DbDataReader>.

The code snippet is as follows:

public Task<IDataReader> ExecuteReaderAsync(string? sql, object? param = null, IDbTransaction? transaction = null, int? commandTimeout = null, CommandType? commandType = null, CancellationToken? cancellationToken = null)
    => ExecuteWithResiliency((s, p, c) => c.ExecuteReaderAsync(s, p, transaction, commandTimeout, commandType), sql, param);    

private async Task<T> ExecuteWithResiliency<T>(Func<string, object, SqlConnection, Task<T>> connectionFunc, string sql, object param = null, [CallerMemberName] string operation = "")
{
    return await _resiliencyPolicy.ExecuteAsync(
        ctx => connectionFunc(sql, param, (SqlConnection)_connection),
        ContextHelper.NewContext((SqlConnection)_connection, _logger, sql, param, operation));
}

The issue arises in the ExecuteReaderAsync method, where I am trying to call the ExecuteWithResiliency method to execute the SQL query and return a Task. However, it gives the following error:

Cannot implicitly convert type 'System.Threading.Tasks.Task<System.Data.Common.DbDataReader>' to 'System.Threading.Tasks.Task<System.Data.IDataReader>'.

I understand that the ExecuteWithResiliency method is designed to be generic, which allows it to work with various asynchronous methods returning different types. However, it seems that there is an incompatibility between System.Data.Common.DbDataReader and System.Data.IDataReader.

How can I modify the code to resolve this issue and make it work correctly while still retaining the generic nature of the ExecuteWithResiliency method?

2. Cannot convert from 'Dapper.CommandDefinition?' to 'string'

public async Task<IReadOnlyList> QueryAsync(CommandDefinition? command, CancellationToken? cancellationToken = null) => (await ExecuteWithResiliency((s, p, c) => c.QueryAsync(command))).AsList();

Any insights or suggestions on how to handle this situation would be highly appreciated.

Can anyone please help me here by providing their guidance

Answer 1

System.Data.Common.DbDataReader is System.Data.IDataReader so you can just await the ExecuteWithResiliency:

public async Task<IDataReader> ExecuteReaderAsync(string? sql, object? param = null, IDbTransaction? transaction = null, int? commandTimeout = null, CommandType? commandType = null, CancellationToken? cancellationToken = null)
    => await ExecuteWithResiliency((s, p, c) => c.ExecuteReaderAsync(s, p, transaction, commandTimeout, commandType), sql, param);