/// <summary>
/// Fetch results for calculated fields.
/// </summary>
/// <remarks>
/// Extension method for processing a single entity and single field.
/// Script errors cause null result.
/// </remarks>
/// <param name="provider">The calculated field provider.</param>
/// <param name="fieldId">The calculated field to evaluate.</param>
/// <param name="entityId">The root entity for which the calculation is being evaluated.</param>
/// <param name="settings">Additional settings.</param>
/// <returns>Calculation results.</returns>
public static object GetCalculatedFieldValue(this ICalculatedFieldProvider provider, long fieldId, long entityId, CalculatedFieldSettings settings)
{
if (provider == null)
{
throw new ArgumentNullException("provider"); // assert false
}
var entities = new[] { entityId };
// Call provider
var results = provider.GetCalculatedFieldValues(fieldId, entities, settings);
// Extract results
if (results == null)
{
throw new Exception("Unexpected null result."); // assert false .. provider isn't following the rules
}
// Parse exception means there are no individual results
if (results.ParseException != null)
{
return(null);
}
CalculatedFieldSingleResult singleResult = results.Entities.FirstOrDefault();
if (singleResult == null)
{
throw new Exception("Could not load calculated field for entity. Likely cause that entity could not be loaded.");
}
// Return result
return(singleResult.Result);
}
/// <summary>
/// Get the calculated field value for the specified entities.
/// </summary>
/// <param name="fieldMetadata">The metadata for the calculated field.</param>
/// <param name="entityIDs">Entities</param>
/// <param name="evalSettings">Evaluation settings</param>
/// <returns>List of results.</returns>
private IReadOnlyCollection <CalculatedFieldSingleResult> GetSingleFieldValues(CalculatedFieldMetadata fieldMetadata, IReadOnlyCollection <long> entityIDs, EvaluationSettings evalSettings)
{
if (fieldMetadata == null)
{
throw new ArgumentNullException("fieldMetadata");
}
if (entityIDs == null)
{
throw new ArgumentNullException("entityIDs");
}
// Handle statically broken calculated-fields
// (may be null due to not being a calculated field, or the script failing to compile)
if (fieldMetadata.Expression == null)
{
// If the calculated field was somehow invalid, return null for values.
return(entityIDs.Select(id => new CalculatedFieldSingleResult(id, null)).ToArray());
}
// Load entities
IReadOnlyCollection <IEntity> entities;
entities = _entityRepository.Get(entityIDs);
var results = new List <CalculatedFieldSingleResult>(entities.Count);
// Perform calculations
foreach (IEntity entity in entities)
{
ExpressionRunResult runResult;
CalculatedFieldSingleResult singleResult;
evalSettings.ContextEntity = entity;
try
{
runResult = _expressionRunner.Run(fieldMetadata.Expression, evalSettings);
singleResult = new CalculatedFieldSingleResult(entity.Id, runResult.Value);
}
catch (EvaluationException ex)
{
singleResult = new CalculatedFieldSingleResult(entity.Id, ex);
}
results.Add(singleResult);
}
return(results);
}
