public static Filter <T> Create(string columnName, string filter, ILogger log)
{
// Use the column name to find the target property
var targetProperty = TypeProperties.FirstOrDefault(p => p.Name.ToLower() == columnName?.ToLower());
//TypeProperties.Select(p => p.Name.ToLower());
// First validate the property exists on the target type
if (targetProperty == null)
{
var error = $"The filter column '{columnName ?? "null"}' does not exist. Filter columns must be one of the following: {FilterableProperties}.";
log?.LogWarning(error);
return(new Filter <T>
{
PropertyName = columnName,
ErrorMessage = error
});
}
// Now validate and split the filter string
var operatorRegex = new Regex("^(eq|ne|lt|gt|le|ge|like):(.+)$");
var operatorMatches = operatorRegex.Matches(filter ?? string.Empty);
if (operatorMatches.Count != 1 && operatorMatches.FirstOrDefault()?.Groups.Count != 3)
{
var error = $"The filter string '{filter ?? "null"}' for column '{columnName}' is not valid. It should match the format '{operatorRegex}'";
log?.LogWarning(error);
return(new Filter <T>
{
PropertyName = columnName,
ErrorMessage = error
});
}
var op = operatorMatches.FirstOrDefault().Groups[1].Value;
var val = operatorMatches.FirstOrDefault().Groups[2].Value;
// If the operator is like, but it's not a string type it's not a valid filter
var propertyType = targetProperty.PropertyType;
if (propertyType.Name != nameof(String) && op == "like")
{
var error = $"The filter column '{columnName}' is not a string, and cannot be use with the 'like' operator.";
log?.LogWarning(error);
return(new Filter <T>
{
PropertyName = columnName,
ErrorMessage = error
});
}
// Now we check the filter string can be parsed into the correct type
var isValueParseable = false;
switch (propertyType.Name)
{
case nameof(String):
isValueParseable = true;
break;
case nameof(Boolean):
bool boolVal;
isValueParseable = bool.TryParse(val, out boolVal);
break;
case nameof(Int16):
case nameof(Int32):
case nameof(Int64):
long longVal;
isValueParseable = long.TryParse(val, out longVal);
break;
case nameof(Decimal):
case nameof(Double):
double doubleVal;
isValueParseable = double.TryParse(val, out doubleVal);
break;
case nameof(DateTime):
DateTime dateTimeVal;
isValueParseable = DateTime.TryParse(val, out dateTimeVal);
break;
case nameof(DateTimeOffset):
DateTimeOffset dateTimeOffsetVal;
isValueParseable = DateTimeOffset.TryParse(val, out dateTimeOffsetVal);
break;
}
var parseError = isValueParseable ? null : $"The filter '{val}' cannot be applied to the property '{columnName}' as it cannot be cast to a '{propertyType.Name}'";
if (!isValueParseable)
{
log?.LogWarning(parseError);
}
return(new Filter <T>
{
PropertyName = columnName,
PropertyType = propertyType,
Operator = op,
Value = val,
IsValid = isValueParseable,
ErrorMessage = parseError
});
}