private static void UpdateManyToManyForeignKeys <T>(this SQLiteConnection conn, T element, PropertyInfo relationshipProperty)
{
var type = typeof(T);
EnclosedType enclosedType;
var entityType = relationshipProperty.GetEntityType(out enclosedType);
var currentEntityPrimaryKeyProperty = type.GetPrimaryKey();
var otherEntityPrimaryKeyProperty = entityType.GetPrimaryKey();
var manyToManyMetaInfo = type.GetManyToManyMetaInfo(relationshipProperty);
var currentEntityForeignKeyProperty = manyToManyMetaInfo.OriginProperty;
var otherEntityForeignKeyProperty = manyToManyMetaInfo.DestinationProperty;
var intermediateType = manyToManyMetaInfo.IntermediateType;
Debug.Assert(enclosedType != EnclosedType.None, "ManyToMany relationship must be a List or Array");
Debug.Assert(currentEntityPrimaryKeyProperty != null, "ManyToMany relationship origin must have Primary Key");
Debug.Assert(otherEntityPrimaryKeyProperty != null, "ManyToMany relationship destination must have Primary Key");
Debug.Assert(intermediateType != null, "ManyToMany relationship intermediate type cannot be null");
Debug.Assert(currentEntityForeignKeyProperty != null, "ManyToMany relationship origin must have a foreign key defined in the intermediate type");
Debug.Assert(otherEntityForeignKeyProperty != null, "ManyToMany relationship destination must have a foreign key defined in the intermediate type");
var primaryKey = currentEntityPrimaryKeyProperty.GetValue(element, null);
// Obtain the list of children keys
var childList = (IEnumerable)relationshipProperty.GetValue(element, null);
var childKeyList = (from object child in childList ?? new List <object>()
select otherEntityPrimaryKeyProperty.GetValue(child, null)).ToList();
var childrenKeysParams = String.Join(",", childKeyList.Select(x => "?"));
// Check for already existing relationships
var currentChildrenQuery = string.Format("select {0} from {1} where {2} == ? and {0} in ({3})",
otherEntityForeignKeyProperty.Name, intermediateType.Name, currentEntityForeignKeyProperty.Name, childrenKeysParams);
var sqlParams = new List <object> {
primaryKey
};
sqlParams.AddRange(childKeyList);
var currentChildKeyList =
from object child in conn.Query(conn.GetMapping(intermediateType), currentChildrenQuery, sqlParams.ToArray())
select otherEntityForeignKeyProperty.GetValue(child, null);
// Insert missing relationships in the intermediate table
var missingChildKeyList = childKeyList.Where(o => !currentChildKeyList.Contains(o)).ToList();
var missingIntermediateObjects = new List <object>(missingChildKeyList.Count);
foreach (var missingChildKey in missingChildKeyList)
{
var intermediateObject = Activator.CreateInstance(intermediateType);
currentEntityForeignKeyProperty.SetValue(intermediateObject, primaryKey, null);
otherEntityForeignKeyProperty.SetValue(intermediateObject, missingChildKey, null);
missingIntermediateObjects.Add(intermediateObject);
}
conn.InsertAll(missingIntermediateObjects);
// Delete any other pending relationship
var deleteQuery = string.Format("delete from {0} where {1} == ? and {2} not in ({3})",
intermediateType.Name, currentEntityForeignKeyProperty.Name,
otherEntityForeignKeyProperty.Name, childrenKeysParams);
conn.Execute(deleteQuery, sqlParams.ToArray());
}