Enhancement: Support for returning IDictionary<string, object> instead of ExpandoObject.

[isaacabraham]

F# doesn't have "out of the box" support for dynamic typing (although it's something that you could add support for). Instead, it would be nice to be able to request an IDictionary<String,Object>> from a query e.g.

let data = conn.ExecuteQuery<IDictionary<string, obj>> "SELECT Col1, Col2 FROM Table" // data is type IEnumerable<IDictionary<string, obj>>

let stuff = data |> Seq.map(fun row -> row.["Col1"]) // get a list of all Col1 values

You can work around this with a one liner, but not everyone (and especially developers with no C# experience) will know how to do this:

let data = conn.ExecuteQuery "SELECT Col1, Col2 FROM Table" // data is type IEnumerable<obj>
let dataAsDict = data |> Seq.cast<IDictionary<string, obj>> // dataAsDict is type IEnumerable<IDictionary<string,obj>>

[isaacabraham]

As background, in F# you can implement the ? operator to do any kind of dynamic lookup so you could do this...

let (?) (x:obj) (key) = (x :?> IDictionary<string, obj>).[key]
let data = conn.ExecuteQuery "SELECT Col1, Col2 FROM Table" // data is type IEnumerable<obj>
let stuff = data |> Seq.map(fun row -> row?Col1) // Note the use of "?" here.

[mikependon]

Just to clarify, the resultset of this is of type IEnumerable<IDictionary<string, object>> right? In which, all the mentioned columns types from the SELECT statement will be casted back to System.Object.

[isaacabraham]

Yes. When you say "all the mentioned columns types" I assume you mean the values in each row (not the column names!)?

And yes, that's what the Expando Object is underneath the hood. It just wraps it in a special interface that C# knows about to give it the dynamic capabilities.

[mikependon]

Yes. When you say "all the mentioned columns types" I assume you mean the values in each row (not the column names!)?

Yes, the name = System.String and the value = System.Object.

[isaacabraham]

Right. I'm not sure what else it could really be? This is what the Expando is behind the scenes. The only other option is potentially to expose the "raw" ADO .NET DB type out so that you can safely ask it what type it is before casting from object to e.g. string etc.

[mikependon]

Cool! I will try to see if I can get the data type back as I already have the proper resolver for that. The only reason I ask is because ExpandoObject is only limited to IDictionary<string, object>.

[isaacabraham]

I think realistically it would probably need to be a <string, obj> collection because each row may have different types in across the columns.

[mikependon]

Atleast I can create a thing like this IEnumerable<IDictionary<string, RowValue>>.

public class RowValue
{
	public Type DataType { get; set; }
	public object Value { get; set; } /* This is always object */
}

But I am also afraid to dictate to the user to bind their code to that RowValue object. So, for the sake of simplicity, let us agree with the IDictionary<string, object>, there I will start the implementation.

[mikependon]

The fix is available at version RepoDb v1.12.0-beta3 or above.

[mikependon]

@isaacabraham - we are closing this ticket now. Please do let us know if you still have questions. Thanks