public static LambdaExpression BuildPredicate(this IEnumerable <FilterGroup> filterGroups, Type type, VariableResolver variableResolver = null, IEnumerable <string> validProperties = null, IDictionary <string, string> propertyMapping = null)
{
if (filterGroups == null)
{
throw new ArgumentNullException(nameof(filterGroups));
}
if (type == null)
{
throw new ArgumentNullException(nameof(type));
}
var arg = new BuildArgument
{
ValidProperties = validProperties,
EvaluationType = type,
VariableResolver = variableResolver,
PropertyMapping = propertyMapping
};
if (!IsValid(filterGroups, arg))
{
throw new InvalidOperationException("The operator or property name is not valid");
}
var allFilterGroups = filterGroups as FilterGroup[] ?? filterGroups.ToArray();
allFilterGroups = allFilterGroups.Where(p => p?.Filters?.Any() == true).ToArray();
if (!allFilterGroups.Any())
{
return(FilterExtensions.AlwaysTruePredicate(type));
}
var param = type.CreateParameterExpression();
var body = allFilterGroups.Aggregate((Expression)null, (current, next) => current == null
? FilterExtensions.BuildBody(next.Filters.ToArray(), param, arg)
: Expression.OrElse(current, FilterExtensions.BuildBody(next.Filters.ToArray(), param, arg)));
return(Expression.Lambda(body, param));
}
internal static EvaluationResult TryBuildPredicate(this IEnumerable <FilterGroup> filterGroups, Type type, BuildArgument arg)
{
if (!filterGroups.Any())
{
return new EvaluationResult
{
Succeeded = true,
Result = FilterExtensions.AlwaysTruePredicate(type)
}
}
;
var allFilterGroups = filterGroups as FilterGroup[] ?? filterGroups.ToArray();
foreach (var filterGroup in allFilterGroups)
{
if (filterGroup is null)
{
throw new InvalidOperationException("FilterGroup can not be null");
}
if (filterGroup.Filters is null)
{
throw new InvalidOperationException("Filters of FilterGroup can not be null");
}
foreach (var filter in filterGroup.Filters)
{
arg.IsValidProperty(filter.Property);
arg.IsValidOperator(filter.Operator);
}
}
if (arg.InvalidOperators.Any() || arg.InvalidProperties.Any())
{
return(new EvaluationResult
{
InvalidProperties = arg.InvalidProperties,
InvalidOperators = arg.InvalidOperators
});
}
try
{
var param = type.CreateParameterExpression();
var body = allFilterGroups.Aggregate((Expression)null, (current, next) => current == null
? FilterExtensions.BuildBody(next.Filters.ToArray(), param, arg)
: Expression.OrElse(current, FilterExtensions.BuildBody(next.Filters.ToArray(), param, arg)));
return(new EvaluationResult
{
Succeeded = true,
Result = Expression.Lambda(body, param)
});
}
catch (Exception ex)
{
return(new EvaluationResult
{
Exception = ex
});
}
}
