使用 ef 核心中的 OR 条件基于所有可选参数的动态查询

Question

I'm not sure if I'm barking up the wrong tree but I wanted to create a function to check if an account exists based on all optional parameters so it can be used to pull data depending on whatever you'd like to check on.

Basically the query should be: where loginName = p1 or loginName = p2 or loginName = p3 but with the paramters all being optional, however at least one will be provided.

This is what I tried so far:

 public async Task<bool> CheckAccountExistsAsync(string loginName = "", string authenticatorId = "", string eId = "")
    {
      if (string.IsNullOrWhiteSpace(loginName) && string.IsNullOrWhiteSpace(authenticatorId) && string.IsNullOrWhiteSpace(eId))
        throw new InvalidOperationException("You must pass at least one parameter");

      return await _context.Accounts.AnyAsync(a =>
          (string.IsNullOrWhiteSpace(loginName) || a.LoginName == loginName)
          || (string.IsNullOrWhiteSpace(authenticatorId) || a.AuthenticatorId == authenticatorId)
          || (string.IsNullOrWhiteSpace(eId) || a.EmployeeId == eId));
    }

Problem with this approach is that if I just pass the loginName, then the query is as follows with the condition completely omitted.:

      SELECT CASE
          WHEN EXISTS (
              SELECT 1
              FROM [Accounts] AS [a]) THEN CAST(1 AS bit)
          ELSE CAST(0 AS bit)
      END

I'm sure I'm missing something, is there a better approach?

Answer 1

What you are using is applicable for optional and expressions, eg

return await _context.Accounts.AnyAsync(a =>
    (string.IsNullOrWhiteSpace(loginName) || a.LoginName == loginName)
    && (string.IsNullOrWhiteSpace(authenticatorId) || a.AuthenticatorId == authenticatorId)
    && (string.IsNullOrWhiteSpace(eId) || a.EmployeeId == eId));

For optional or you have to use optional and sub conditions and add additional check for all optional parameters missing, eg

return await _context.Accounts.AnyAsync(a =>
    (string.IsNullOrWhiteSpace(loginName)
    && string.IsNullOrWhiteSpace(authenticatorId)
    && string.IsNullOrWhiteSpace(eId))
    || (!string.IsNullOrWhiteSpace(loginName) && a.LoginName == loginName)
    || (!string.IsNullOrWhiteSpace(authenticatorId) && a.AuthenticatorId == authenticatorId)
    || (!string.IsNullOrWhiteSpace(eId) && a.EmployeeId == eId));