private AFAttributeList CreateBrandNewInputList(object context)
{
// PRO TIP:
// See comments in GetInputs where you want to avoid _cachedInputAttrs.Add or AddRange.
// For thread safety, use a brand new list that is local to this method.
// Start with a brand new list
var brandNewList = new AFAttributeList();
AFAttribute measurement = null;
// First and foremost we need a measurement attribute, which is the centerpoint to compare against limits.
if (UseParentAttribute)
{
// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFDataReference_Attribute.htm
// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFAttribute_Parent.htm
measurement = Attribute.Parent;
if (measurement == null)
{
throw new Exception("Root-level attribute does not have a parent. You must define 'MeasAttr=something' in the ConfigString.");
}
}
else
{
// Let's offer some bit of name substitution.
// However, the GetInputs method lacks any timeContext, which restricts @value substitution
// to current values only. This restriction is fine for static attributes.
// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/T_OSIsoft_AF_AFNameSubstitutionType.htm
var path = SubstituteParameters(_measAttrName, this, context, timeContext: null);
// Note that the final fetch of the measurement attribute is *relative* to the current Attribute.
// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFAttribute_Attributes.htm
measurement = Attribute.Attributes[path];
if (measurement == null)
{
throw new Exception($"MeasAttr '{_measAttrName}' not found. Check your ConfigString.");
}
}
if (!IsNumericType(Type.GetTypeCode(measurement.Type)))
{
throw new Exception($"MeasAttr does not have a numeric Type.");
}
// If the list will have any items, the measurement will always be at Index 0.
brandNewList.Add(measurement);
// Let the CDR automatically fetch the associated limits.
// These could come back in any order, plus some or all may be missing!
// Geez, doesn't that make it fun and challenging!
// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFAttribute_GetAttributesByTrait.htm
brandNewList.AddRange(measurement.GetAttributesByTrait(AllowedTraits));
return(brandNewList);
}