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Custom JQ Functions

Hugr extends the standard jq language with custom functions for common server-side tasks. These functions are available in all JQ contexts — inline jq() queries, the /jq-query REST endpoint, and _jq variable input transformations.

Custom functions are organized into three categories:

Time Functions​

localTime​

Returns the current local time (server timezone).

Signature: localTime (no arguments, no input required)

localTime
# "2024-06-15T16:30:45+02:00" (example, depends on server timezone)

utcTime​

Returns the current UTC time.

Signature: utcTime (no arguments, no input required)

utcTime
# "2024-06-15T14:30:45Z"

unixTime​

Converts a time value to a Unix timestamp in seconds. When the input is null, returns the current UTC Unix timestamp.

Signature: <time_value> | unixTime

"2024-06-15T14:30:45Z" | unixTime
# 1718457045

"2024-06-15T14:30:45Z" | roundTime("day"; "UTC") | unixTime
# 1718409600

null | unixTime
# (current UTC unix timestamp)

roundTime​

Truncates or rounds a time value to the given period.

Signatures:

  • <time_value> | roundTime(period)
  • <time_value> | roundTime(period; timezone)

The optional timezone parameter is an IANA timezone string (e.g. "America/New_York").

Named Periods​

PeriodResult
"second" / "seconds"Round to nearest second
"minute" / "minutes"Round to nearest minute
"hour" / "hours"Truncate to start of hour
"day"Truncate to start of day
"month" / "months"Truncate to first of the month
"year" / "years"Truncate to January 1st
"monday" .. "saturday"Truncate to the given weekday

Any Go time.Duration string (e.g. "15m", "2h30m") is also accepted and rounds using time.Round.

"2024-06-15T14:30:45Z" | roundTime("day")
# "2024-06-15T00:00:00Z"

"2024-06-15T14:30:45Z" | roundTime("month"; "UTC")
# "2024-06-01T00:00:00Z"

"2024-06-15T14:30:45Z" | roundTime("monday")
# "2024-06-10T00:00:00Z" (previous Monday)

"2024-06-15T14:30:45Z" | roundTime("15m")
# "2024-06-15T14:30:00Z"

timeAdd​

Adds a Go duration string to a time value.

Signatures:

  • <time_value> | timeAdd(duration)
  • <time_value> | timeAdd(duration; timezone)

Duration format follows Go's time.Duration syntax: "1h", "30m", "2h30m", "-1h" (negative to subtract).

"2024-06-15T14:30:45Z" | timeAdd("2h")
# "2024-06-15T16:30:45Z"

"2024-06-15T14:30:45Z" | timeAdd("-30m"; "UTC")
# "2024-06-15T14:00:45Z"

datePart​

Extracts a component from a time value as an integer.

Signatures:

  • <time_value> | datePart(part)
  • <time_value> | datePart(part; timezone)

Part Reference​

PartReturns
"second"0–59
"minute"0–59
"hour"0–23
"day"1–31
"month"1–12
"year"e.g. 2024
"weekday"1 (Monday) – 7 (Sunday)
"yearday"1–366
"2024-06-15T14:30:45Z" | datePart("hour")
# 14

"2024-06-15T14:30:45Z" | datePart("weekday")
# 6 (Saturday)

Time Input Formats​

All time functions accept the following input formats:

FormatExampleNotes
RFC 3339 string"2024-06-15T14:30:45Z"Standard date-time format
Unix timestamp (float64)1718457045Timezone parameter applies only to this format
time.Time valueOutput of localTime, utcTime, or other time functionsFor piping/chaining

Chaining Examples​

Time functions can be piped together for complex operations:

# Get start of day, then add 9 hours (business hours start)
"2024-06-15T14:30:45Z" | roundTime("day") | timeAdd("9h") | {
    hour: datePart("hour"),
    day:  datePart("day")
}
# {"hour": 9, "day": 15}
# Get first day of current year in UTC
utcTime | roundTime("year"; "UTC") | {
    month: datePart("month"; "UTC"),
    day:   datePart("day"; "UTC")
}
# {"month": 1, "day": 1}

Query Engine Functions​

queryHugr​

Executes a GraphQL query against the hugr query engine from within a JQ expression. This enables data enrichment, lookups, and cross-referencing inside transformations.

Signatures:

  • queryHugr(query)
  • queryHugr(query; variables)

The result can be bound to a variable using as:

queryHugr("{ users { name } }").users
# [{"name": "alice"}, {"name": "bob"}]

queryHugr("{ config { multiplier } }") as $cfg | .value * $cfg.config.multiplier
tip

queryHugr is extensively documented with 20+ examples in the JQ Transformations — queryHugr() Function section, including variable passing, the as binding pattern, nested queries, and error handling.

Authentication Functions​

authInfo​

Returns the current authentication context as an object, or null if the request is not authenticated.

Signature: authInfo (no arguments, no input required)

Return structure (when authenticated):

{
  "userId": "user-123",
  "userName": "alice",
  "role": "admin"
}

When not authenticated: returns null.

# Get current user's role
authInfo.role
# "admin"

# Conditional logic based on authentication
if authInfo then
  "Hello, " + authInfo.userName
else
  "Anonymous"
end