public VariablePreviewStruct()
{
this.Id = 0;
this.Name = "";
this.Description = "";
this.isOptional = true;
this.Unit = new ItemStruct();
this.convertibleUnits = new List<ItemStruct>();
this.DataType = "";
this.Constraints = new Dictionary<long, string>();
this.Attribute = new AttributePreviewStruct();
this.inUse = false;
}