Dapper & MS Access - Read works, Write doesn't

Question

Let\'s start by getting this out of the way: I\'m stuck using an MS Access DB and I can\'t change it.

This works fine:

using (OleDbConnection conn =          


        

Answer 1

After some digging, I was able to find a cause:

Below is CreateParamInfoGenerator delegate from dapper's SqlMapper:

    public static Action<IDbCommand, object> CreateParamInfoGenerator(Identity identity)
    {

        // code above here
        IEnumerable<PropertyInfo> props = type.GetProperties().OrderBy(p => p.Name); 

The props is your unanimous param which gets re-ordered by OrderBy(p => p.Name), which moves city upfront.

new { firstName = "John", city = "SomeCity", lastName = "Smith" }

Props is then being added to the IDbCommand Parameters where the order is important.

If I comment out OrderBy() clause, then everything works.

I also tested DynamicParameters and intentionally re-ordered the attributes to move city upfront:

        var parameters = new DynamicParameters();
        parameters.Add("city", "SomeCity");
        parameters.Add("firstName", "John");
        parameters.Add("lastName", "Smith");

        var result = dbConnection.Query<string>(
          "update Students set FirstName = @firstName, City = @city where LastName = @lastName",
          parameters
        );

The above did not work as well, so the order of attributes is the reason!

I guess you can modify your local copy of SqlMapper for now and remove OrderBy() and wait for an official verdict from Marc...

Hope this helps.

Answer 2

I had a similar issue, what I did was to use parameter names like @param1, @param2 instead of @name,@id,@price so the order stays the same without having to modify SQLMapper.cs file.

Something like

public void Update(Movie movie)
{
  var sql = "UPDATE myDB.movies set title=@param1, genre=@param2 where ID=@param3";
  db.Execute(sql, new { param1 = movie.Title, param2 = movie.Genre, param3 = movie.ID });
}