/// <summary>
/// Adds all fields to a graph type by iterating through the model type properties.
/// </summary>
/// <typeparam name="T">The model type.</typeparam>
/// <param name="type"></param>
/// <param name="handleIdProperty">If set to true, the Id property is added as field. Default is false.</param>
public static void AddFieldsFromType <T>(this ObjectGraphType <object> type, bool handleIdProperty = false)
{
var properties = typeof(T).GetExactProperies();
foreach (var property in properties)
{
var typeName = property.PropertyType.Name;
var propertyName = property.Name.ToFirstLower();
// handle Id
if (propertyName == "id")
{
// skip property named "id" if desired. May be skipped because it is handled already in NodeType.
if (!handleIdProperty)
{
continue;
}
type.AddIdField();
continue;
}
// convert all foreign key id fields to be global unique
if (propertyName.EndsWith("Id"))
{
type.Field <IdGraphType>(propertyName, null, null, context =>
{
var node = context.Source;
return(GlobalId.ToGlobalId(property.Name.Remove(propertyName.Length - 2), property.GetValue(node).ToString()));
});
continue;
}
// create primitive fields like ints, strings, floats etc.
if (property.PropertyType.IsSimpleType())
{
type.CreateFieldFromPrimitiveProperty(property);
continue;
}
// generate connection field for collection / list
if (property.PropertyType.GetInterface("ICollection") != null && property.PropertyType.IsGenericType())
{
// create an ObjectType<itemType>
var itemType = property.PropertyType.GenericTypeArguments[0];
var graphQLType = typeof(NodeObjectType <>).MakeGenericType(itemType);
graphQLType = graphQLType.ConvertToVirtualType();
// construct resolver
Func <ResolveFieldContext <object>, object> resolver = (context) => {
// get the collection / list items
// TODO: crazy thoughts: what if this property was not loaded yet?
// If, for example, a list of users is loaded by a repository, the roles
// of each user may not have been loaded.
// Could it be possibe to somehow get and call a repository here and perform
// something like lazy loading?
// Further: if a collection of object is loaded, could it be easily possible to
// perform batch loading and have some temporaly cache for this requests?
var items = context.Source.GetProperyValue(propertyName);
// constuct a type like Connection<Order, TId>
var connectionType = typeof(Connection <,>);
var idType = itemType.GetIdType();
connectionType = connectionType.MakeGenericType(new[] { itemType, idType });
// call like new Connection<Order, TId>(items)
var connection = Activator.CreateInstance(connectionType, items);
return(connection);
};
type.AddConnectionField(itemType, resolver, propertyName, null);
continue;
}
// create complex property fields
var complexType = typeof(NodeObjectType <>).MakeGenericType(property.PropertyType).ConvertToVirtualType();
type.Field(complexType, propertyName);
}
}