How to get property name and value from generic model with generic list?

Question

Using the following model as an example.

public class FooModel
{
    public FooModel()
    {
        Bars= new List<BarModel>();
    }

    [ManyToMany]
    public IList<BarModel> Bars{ get; set; }
}

public class BarModel
{
    public int Id { get; set; }
}

I need to extrapolate the List<BarModel> from a fooModel object, and build up a Dictionary<string, object> from each BarModel in the list.

---

Let's say I create the following object.

var fooModel = new FooModel();
var bar1 = new BarModel {Id = 1};
var bar2 = new BarModel {Id = 2};
fooModel.Bars = new List<BarModel>{bar1,bar2};

And now I want to get all properties within Foo that have the [ManyToMany] attribute.

// First I call the method and pass in the model
DoSomething(fooModel);

// Next I extract some values (used elsewhere)
public DoSomething<TModel>(IModel model){

    var dbProvider = ...;
    var mapper = new AutoMapper<TModel>();
    var tableName = GetTableName( typeof( TModel ) );

    UpdateJoins( dbProvider, fooModel, tableName, mapper );
}

// Finally I begin dealing with the collection.
private static void UpdateJoins<TModel> ( IDbProvider dbProvider, TModel model, string tableName, IAutoMapper<TModel> mapper ) where TModel : class, new()
{
    foreach (
        var collection in
             model.GetType()
                  .GetProperties()
                  .Where( property => property.GetCustomAttributes( typeof( ManyToManyAttribute ), true ).Any() ) )
    {

        if ( !IsGenericList( collection.PropertyType ) )
            throw new Exception( "The property must be a List" );

        // Stuck Here - pseudo code
        //====================
        foreach (loop the collection)

             var collectionName = ...;  // Bar
             var nestedPropertyName = ...;  // Id
             var rightKey = collectionName + nestedPropertyName; // BarId
             var nestedPropertyValue = ...; // 1

    }
}

In the example above, the OUTER foreach is only going to run ONCE because there is only one Property within FooModel that is decorated with the [ManyToMany] attribute.

Therefore PropertyInfo property is a List<BarModel>

How do I do the above INNER foreach and extract the required data?

Answer 1

This may get you on the right track. The idea is if you encounter a [ManyToMany] / generic list you reflect it using recursive call to the same method and then flatten the returned values to form a unique key. You probably will need to tweak it to suit your problem. The below code returns a dictionary with formatted key strings built from collection names, indexes and property names. E.G:

Bars[0].Id = 1
Bars[1].Id = 2

Code:

//This is just a generic wrapper for the other Reflect method
private static Dictionary<string, string> Reflect<TModel>(TModel Model)
{
  return Reflect(Model.GetType(), Model);
}

private static Dictionary<string, string> Reflect(Type Type, object Object)
{
  var result = new Dictionary<string, string>();

  var properties = Type.GetProperties();

  foreach (var property in properties)
  {
    if (
      property.GetCustomAttributes(typeof(ManyToManyAttribute), true).Any() &&
      property.PropertyType.GetGenericTypeDefinition() == typeof(IList<>))
    {
      var genericType = property.PropertyType.GetGenericArguments().FirstOrDefault();
      var listValue = (IEnumerable)property.GetValue(Object, null);

      int i = 0;
      foreach (var value in listValue)
      {
        var childResult = Reflect(genericType, value);
        foreach (var kvp in childResult)
        {
          var collectionName = property.Name;
          var index = i;
          var childPropertyName = kvp.Key;
          var childPropertyValue = kvp.Value;

          var flattened = string.Format("{0}[{1}].{2}", collectionName, i, childPropertyName);
          result.Add(flattened, childPropertyValue);
        }

        i++;
      }
    }
    else
    {
      result.Add(property.Name, property.GetValue(Object, null).ToString());
    }
  }

  return result;

}