C＃：通过2d对象数组将参数传递给函数

Question

I'm trying to write a neat little generic Sql method that will accept a SQL Query and a list of parameters, and return a result. I want to keep it neat enough that I can call it using one line from any other code.

Is there any really awesomely neat way of doing this? I don't want to create all the SqlParameters in the calling code, and I don't want to have to pass and split a string. In the past I've used a string[] array and accepted every odd member as a parameter name and every even as a param value but that's too easy to screw up when calling the method.

Ideally I'd love to do just this:

Data.SQL("Select * from Table where my_id = @my_id", { my_id = 1 });

I know that's a little unrealistic, So I tried this:

Data.SQL("Select * from Table where my_id = @my_id", new Object[,]{ { "my_id", 1 } });

However when I try and handle that on the other end, I get nothing but trouble:

public static Object SQL(String command, Object[,] parameters = null){
     [ ... reusable SQL code here... ] 

     foreach(Object[] p in parameters){
            cmd.Parameters.Add(new SqlParameter(p[0].ToString(), p[1].ToString());
     }
}

Looks fine, but throws an error on the foreach statement

foreach (Object[] p in parameters)

Unable to cast object of type 'System.String' to type 'System.Object[]'

But I didn't pass it an array of System.String. What I passed was a 2D System.Object[]! Wasn't it?

Maybe this is just some small code problem, something stupid I'm doing wrong. It usually is. But I'm figuring you guys know some even neater way to do the above.

Answer 1

Ideally I'd love to do just this:

 Data.SQL("Select * from Table where my_id = @my_id", { my_id = 1 }); 

I know that's a little unrealistic,

Well, in exactly that form, yes... but try this instead:

Data.SQL("Select * from Table where my_id = @my_id", new { my_id = 1 });

That will use an anonymous type for the argument, which you can examine by reflection. You probably only need a single parameter (ie it would be SQL(string sql, object parameters) ) because you would pass multiple parameters in a single object:

Data.SQL("Select * from Table where my_id = @my_id and name = @name",
         new { my_id = 1, name = "Jon" });

More alternatives:

• If you're using C# 4, you might find dynamic typing useful; look at what Massive does for example.

• As mentioned by Ray, you could pass in a Dictionary<string, object> ; again, C# 3 makes this easier than otherwise:

   Data.SQL("...", new Dictionary<string, object> { { "my_id", 1 }, { "name", "Jon" }}); 

---

EDIT: As for the exact problem you're running into: you need to understand the difference between a rectangular array (eg Object[,] ) and a jagged array (eg Object[][] ). The latter is an array of arrays, which is how you're trying to use the parameter, but it's really only a rectangular array. Changing your parameter type to Object[][] may well fix that immediate problem - but personally I'd move to one of the approaches above. I'd also try to avoid making everything into a string, by the way.