CODEWITHSUNDEEP
data-annotationsdapper
Robert
Robert

Reputation: 1794

Dapper.NET mapping with Data Annotations

So I have a class with a property like this:

public class Foo
{
  [Column("GBBRSH")
  public static string Gibberish { get; set;}
  ....
}

For saving data, I have it configured so that the update/insert statements use a custom function:

public static string GetTableColumnName(PropertyInfo property)
{
  var type = typeof(ColumnAttribute);
  var prop = property.GetCustomAttributes(type, false);

  if (propr.Count() > 0)
    return ((ColumnAttribute)prop.First()).Name;
  return property.Name;
}

This handles fine, but I noticed that when I go to retrieve the data, it isn't actually pulling data back via the function for this particular column. I noticed that the other data present was pulled, but the column in question was the only field with data that didn't retrieve.

1) Is there a way to perhaps use the GetTableColumnName function for the retrieval part of Dapper?

2) Is there a way to force Dapper.NET to throw an exception if a scenario like this happens? I really don't want to have a false sense of security that everything is working as expected when it actually isn't (I get that I'm using mapping that Dapper.NET doesn't use by default, but I do want to set it up in that manner).

edit:

I'm looking in the SqlMapper source of Dapper and found:

 private static IEnumerable<T> QueryInternal<T>(params) // my knowledge of generics is limited, but how does this work without a where T : object?
 {
   ...
   while (reader.Read())
   {
     yield return (T)func(reader);
   }
   ...
 }

so I learned about two things after finding this. Read up on Func and read up on yield (never used either before). My guess is that I need to pass reader.Read() to another function (that checks against column headers and inserts into objects appropriately) and yield return that?

Upvotes: 1

Views: 7284

Answers (1)

Alex
Alex

Reputation: 8116

You could change your select statement to work with aliases like "SELECT [Column("GBBRSH")] AS Gibberish" and provide a mapping between the attribute name and the poco property name.

That way, Dapper would fill the matching properties, since it only requires your POCO's to match the exact name of the column.

Upvotes: 2

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