Protected validProtected validDetermines if the value and lookupKey for the result should be handled by this class. When true, convert() supports these parameters.
Let's suppose you want to convert a Date object into a number of days, without taking the time into account.
supportsValue(value, LookupKey.Date, LookupKey.Number) may be appropriate. However, LookupKey.Number
may be too broad, since you might want a converter that handles the number of hours or weeks.
In that case, create a LookupKey for those new cases, and expect the user to supply it
in conditionConfig.conversionLookupKey.
supportsValue(value, LookupKey.Date, "Weeks");
If you don't supply the second parameter, the value will be evaluated through a DataTypeIdentifier.
In the case of a Date object, it will be evaluated as a LookupKey.Date because that's what
DateDataTypeIdentifier returns for a Date object.
// supports a date object using LookupKey.Date or LocalDate
// and converts it to a number of days using resultLookupKey of LookupKey.Number
// or to a number of weeks using resultLookupKey of "Weeks".
class DateToNumberConverter implements IDataTypeConverter {
supportsValue(value: any, sourceLookupKey: string | null, resultLookupKey: string): boolean {
if (value instanceof Date)
{
if (resultLookupKey !== LookupKey.Number && resultLookupKey !== "Weeks")
return false;
if (!sourceLookupKey)
return true;
if (sourceLookupKey === LookupKey.Date || sourceLookupKey === LookupKey.LocalDate)
return true;
}
return false;
}
let dateValue = new Date();
let converter = new DateToNumberConverter();
converter.supportsValue(dateValue, null, LookupKey.Number); // = true
converter.supportsValue(dateValue, LookupKey.Date, LookupKey.Number); // = true
converter.supportsValue(dateValue, LookupKey.LocalDate, LookupKey.Number); // = true
converter.supportsValue(dateValue, LookupKey.Date, "Weeks"); // = true
converter.supportsValue(dateValue, LookupKey.LocalDate, "Weeks"); // = true
converter.supportsValue(dateValue, LookupKey.TimeOfDay, LookupKey.Number); // = false
Don't look for valid data within the object. The convert() function is responsible for reporting invalid data in supported values.
The value to be converted. Check its type and possibly its content.
The value can represent several other values, such as a Date represents date, time, etc. Use this when you need to distinguish between them. If null or '', evaluate the value itself, such as checking its class (using 'instanceof') or for properties of an interface that you are using. This is often the dataType property of the ValueHost.
true when its own convert() method should handle the value.
Determines if the value and sourceLookupKey for the result are supported by this class. This is not enough to convert, because it doesn't specify the resultLookupKey. Use canConvert() for that. Instead, this is used to export the supportedResultLookupKeys as you work through a list of close matches.
Perform the conversion of the value to the resultLookupKey.
The value to be converted. Check its type and possibly its content.
The value can represent several other values, such as a Date represents date, time, etc. Use this when you need to distinguish between them. If null or '', evaluate the value itself, such as checking its class (using 'instanceof') or for properties of an interface that you are using. This is often the dataType property of the ValueHost.
The converted value. If the value is not convertable, return undefined.
Identifies lookup keys that can be passed into the sourceLookupKey parameter of canConvert() to identify the value.
SourceLookupKey is used to distinguish between different types of values that can be derived from the same object. If this class allows sourceLookupKey to be null, include null in the array. When null, we are saying that this converter is the default for the data type of the expected value.
Identifies lookup keys that are the resulting value of the conversion supported. supportsValue() will only return true with one of these keys in its resultLookupKey parameter. While the actual data type output may be a number, string, boolean, or Date, do not use those as lookup keys unless that is the preferred lookup key. Instead, use the LookupKey for the data type that the value represents. For example, a Date object converted to a number of seconds should use LookupKey.TimeOfDay, not LookupKey.Number. If you made it return LookupKey.Number, it would be ambiguous with another converter that generically converts a Date to a number.
Generated using TypeDoc v0.25.12
For JavaScript Date objects to convert just the time of day into a number of minutes. See also TimeOfDayHMSOnlyConverter. It assumes the Date object is in UTC and returns a UTC date.
value - expected to be a Date object in UTC sourceLookupKey = LookupKey.TimeOfDay resultLookupKey = "Number" or "Minutes"