Convert DataRow to Object with AutoMapper

Question

I can successfully map from IDataReader to a List of objects but when I want to take one DataRow it doesn't seem to work as expected.

Am I missing something simple here?

[TestFixture]
public class AutomapperTest
{
    [Test]
    public void TestMethod1()
    {
        DataTable dt = new DataTable("contact");
        dt.Columns.Add("FirstName");
        dt.Columns.Add("LastName");
        dt.Columns.Add("Line1");
        dt.Columns.Add("Line2");
        dt.Columns.Add("Line3");
        dt.Columns.Add("Suburb");
        dt.Columns.Add("State");
        dt.Columns.Add("Postcode");

        DataRow row = dt.NewRow();
        row.ItemArray = new [] { "Little", "Johnny", 
                                 "1 Random Place", "", "", 
                                 "Windsor", "Qld", "4030" };

        var dest = Mapper.DynamicMap<myObject>(row);

        Assert.AreEqual(row["FirstName"], "Little");
        Assert.IsNotNull(dest);
        Assert.AreEqual(dest.FirstName, "Little");
    }
}

Destination type:

public class myObject
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Line1 { get; set; }
    public string Line2 { get; set; }
    public string Line3 { get; set; }
    public string Suburb { get; set; }
    public string State { get; set; }
    public string Postcode { get; set; }
}

Darek · Accepted Answer · 2014-07-10T01:56:50.240

11

You will have to implement your own custom value resolver

https://github.com/AutoMapper/AutoMapper/wiki/Custom-value-resolvers

UPDATE

public class CustomResolver : IValueResolver
{
    public ResolutionResult Resolve(ResolutionResult source)
    {
        return source.New( Convert.ChangeType((source.Context.SourceValue as DataRow)[source.Context.MemberName], source.Context.DestinationType));
    }
}

and here is how to use it

Mapper.CreateMap<DataRow,myObject>().ForAllMembers(m=>m.ResolveUsing<CustomResolver>());
var dest = Mapper.Map<myObject>(row);

I recommend using Dapper. That way your data coming from database will be strongly typed or dynamic, and Automapper should be able to figure out the mappings.

CSV files can be read by Dapper through ODBC, I believe. But for CSV I'd recommend the LinqToCSV Nuget package instead.

edited Jul 10 '14 at 01:56

answered Jul 10 '14 at 00:28

Darek

4,687
31
47

Thanks - that's unfortunate, it hardly seems worth it for a small number of columns. – Geoff Jul 10 '14 at 00:36
Consider Dapper with Automapper. – Darek Jul 10 '14 at 00:39
Can you give an example how custom value resolver can help here? – Sergey Berezovskiy Jul 10 '14 at 00:40
@SergeyBerezovskiy Is the sample OK? – Darek Jul 10 '14 at 01:51
I've learned something too @Geoff. It was my first true encounter with Automapper and custom value resolvers. – Darek Jul 10 '14 at 13:12
2

Trying to get this to work for version 5.0.2 with the changed interface, maintainer says "AutoMapper doesn't support this scenario." – PJ7 Sep 07 '16 at 18:37
Could you post a new case and link? – Darek Sep 17 '16 at 12:53

score 0 · Answer 2 · answered Aug 24 '23 at 09:26

Another way is to use the ITypeConverter:

Create a custom TypeConverter class:

public class DataRowConverter : ITypeConverter<DataRow, Object>
{
    Object ITypeConverter<DataRow, Object>.Convert(DataRow source, Object destination, ResolutionContext context)
    {
        foreach (DataColumn col in source.Table.Columns)
        {
            var value = source[col].ToString();

            PropertyInfo prop = destination.GetType().GetProperty(
                col.ColumnName,
                BindingFlags.Instance | BindingFlags.Public | BindingFlags.SetProperty | BindingFlags.IgnoreCase);

            if (prop != null && prop.CanWrite)
            {
                prop.SetValue(destination, value, null);
            }
        }

        return destination;
    }
}

Then set the config:

cfg.CreateMap<DataRow, Object>().ConvertUsing<DataRowConverter>();

Finally, use the mapper as usual:

var results = new List<SearchResult>();
foreach (DataRow row in Res.data.Tables[0].Rows)
{
    var obj = mapper.Map<SearchResult>(row);
    results.Add(obj);
}

It should work with the latest version of AutoMapper.

Convert DataRow to Object with AutoMapper

2 Answers2

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