AutoMapper pivot configuration

In our project we’re AutoMapper to transform a list of name – value pairs to objects with properties. It pivots by mapping the name of the pair to the property and assigning the value to it.

We created an extension method that takes a Func to return the Name and a Func to return the Value. The configuration is very short when using this extension method. See the listing below

Mapper.CreateMap<List<Data>, Person>()
      .ConvertFromList(x => x.Name, x => x.Value);

The List with Data objects is the name-value pairs, where Person is the actual object with the properties mapped by the name.

The extension method looks impressive, but that is because of the Name and Value Func and not because of the complexity.

public static IMappingExpression<List<TSource>, TDest> ConvertFromList<TSource, TDest>(
    this IMappingExpression<List<TSource>, TDest> exp,
    Func<TSource, string> name,  // Function to return the Name
    Func<TSource, object> value) // Function to return the Value 
{
    var allPropertyFlags = BindingFlags.Instance | 
                           BindingFlags.Public | 
                           BindingFlags.NonPublic;
    foreach (var prop in typeof(TDest).GetProperties(allPropertyFlags)) {
        // map with value (implicit conversion) of the first item with Name equal to the property name
        exp.ForMember(prop.Name, map => map.MapFrom(src => value(src.First(s => name(s) == prop.Name))));
        // only when name exists will there be mapped
        exp.ForMember(prop.Name, map => map.Condition(src => src.Any(s => name(s) == prop.Name)));
    }
    return exp;
}

We’re happy with the current configuration, but we think case sensitivity could get an issue.

References

AutoMapper Dictionary Flattening on stackoverflow, origional source for our solution

About erictummers

My work as a recruited developer changes almost every month. I like challenges and sharing the solutions with others. On my blog I’ll mostly post about my work, but expect an occasional home project, productivity tip and tooling review.
This entry was posted in Development and tagged , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s