DATE, DATETIME, and INTERVAL conversions

GWS serializes DATE, DATETIME, and INTERVAL values as JSON strings using either the Genero BDL native format or standard RFC 3339 / ISO 8601 formats.

The output format depends on how the client stub is generated or how the serializer is configured. Three output modes apply to DATETIME, two apply to INTERVAL, and DATE is unaffected by the mode.

The iso8601-local mode includes the time zone offset of the server process at runtime. As a result, the same DATETIME value can produce different output on servers configured with different time zones.

Table 1. JSON string representations by output mode
BDL type	`native` (BDL default)	`iso8601` (RFC 3339 UTC)	`iso8601-local` (RFC 3339 local offset)
`DATE`	`"2024-11-05"`	`"2024-11-05"`	`"2024-11-05"`
`DATETIME YEAR TO DAY`	`"2024-11-05"`	`"2024-11-05"`	`"2024-11-05"`
`DATETIME YEAR TO SECOND`	`"2024-11-05 09:15:58"`	`"2024-11-05T08:15:58Z"`	`"2024-11-05T09:15:58+01:00"`
`DATETIME YEAR TO FRACTION(3)`	`"2024-11-05 09:15:58.123"`	`"2024-11-05T08:15:58.123Z"`	`"2024-11-05T09:15:58.123+01:00"`
`INTERVAL YEAR TO MONTH`	`" 2-03"`	`"P2Y03M"`	`"P2Y03M"`
`INTERVAL DAY(9) TO FRACTION(5)`	`" 2 10:30:00.00000"`	`"P2DT10H30M00.00000S"`	`"P2DT10H30M00.00000S"`

DATE and DATETIME

OpenAPI represents date and time values as strings. The format keyword distinguishes between date-only and date-time values.

DATE

A DATE value is represented as a string with the date format:

schema
type         "string"
format       "date"

In this case, fglrestful generates a Genero BDL DATE type in the client stub.

DATETIME

For DATETIME values, GWS sets the format keyword based on the qualifier:

A DATETIME YEAR TO DAY is mapped to:
```
schema
type         "string"
format       "date"
```
because the value has no time component.
A DATETIME ending at MINUTE, SECOND, or FRACTION(n) is mapped to:
```
schema
type         "string"
format       "date-time"
```
A DATETIME with other qualifiers (for example, YEAR TO MONTH or HOUR TO MINUTE) is mapped to a plain string with no format, because no RFC 3339 representation is available:
```
schema
type         "string"
```

By default, fglrestful generates a DATETIME YEAR TO SECOND type in the client stub.

You can control the fractional precision by setting the --datetime-fraction option in the fglrestful command. For example:

--datetime-fraction=3

This generates a DATETIME YEAR TO FRACTION(3) type.

fglrestful generates the data type in the client stub, mapping it to a Genero BDL DATETIME YEAR TO SECOND type.

INTERVAL

OpenAPI represents durations as strings using the duration format:

schema
type         "string"
format       "duration"

GWS maps INTERVAL values (both DAY TO SECOND and YEAR TO MONTH) to this representation.

By default, fglrestful generates a INTERVAL DAY(9) TO FRACTION(5) type in the client stub.

You can override this behavior by using the --interval option to select a different qualifier or to restore the previous mapping to STRING.

The duration format is defined in the OpenAPI Format Registry (JSON Schema 2019-09 / OpenAPI 3.1). Tools that do not support this format treat the value as a plain string.