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1.5 KiB
1.5 KiB
User Defined Functions
Extend BaraQL with custom functions.
Usage
import barabadb/query/udf
var reg = newUDFRegistry()
# Register standard library
reg.registerStdlib() # abs, sqrt, pow, lower, upper, len, trim, substr, toString, toInt
# Custom function
reg.register("greet", @[UDFParam(name: "name", typeName: "str")],
"str", proc(args: seq[Value]): Value =
return Value(kind: vkString, strVal: "Hello, " & args[0].strVal & "!"))
Standard Library Functions
| Function | Description | Example |
|---|---|---|
abs(n) |
Absolute value | abs(-5) → 5 |
sqrt(n) |
Square root | sqrt(16) → 4 |
pow(n, e) |
Power | pow(2, 3) → 8 |
lower(s) |
Lowercase | lower('ABC') → 'abc' |
upper(s) |
Uppercase | upper('abc') → 'ABC' |
len(s) |
Length | len('hello') → 5 |
trim(s) |
Trim whitespace | trim(' hello ') → 'hello' |
substr(s, start, len) |
Substring | substr('hello', 0, 3) → 'hel' |
toString(n) |
Convert to string | toString(123) → '123' |
toInt(s) |
Convert to integer | toInt('123') → 123 |
Function Registration
reg.register(
name: "my_function",
params: @[
UDFParam(name: "arg1", typeName: "str"),
UDFParam(name: "arg2", typeName: "int32")
],
returnType: "str",
body: proc(args: seq[Value]): Value =
# Implementation
result = Value(kind: vkString, strVal: "")
)
Using UDFs in Queries
SELECT greet(name) FROM users;