Struct pgrx::callconv::FcInfo

pub struct FcInfo<'fcx>(/* private fields */);

Implementations

impl<'fcx> FcInfo<'fcx>

pub unsafe fn from_ptr(fcinfo: FunctionCallInfo) -> FcInfo<'fcx>

Constructor, used to wrap a raw FunctionCallInfo provided by Postgres.

Safety

This function is unsafe as we cannot ensure the fcinfo argument is a valid pg_sys::FunctionCallInfo pointer. This is your responsibility.

pub fn raw_args(&self) -> &[NullableDatum]

Retrieve the arguments to this function call as a slice of pgrx_pg_sys::NullableDatum

pub unsafe fn as_mut_ptr(&self) -> FunctionCallInfo

Retrieves the internal pg_sys::FunctionCallInfo wrapped by this type. A FunctionCallInfo is a mutable pointer to a FunctionCallInfoBaseData already, and so that type is sufficient.

pub unsafe fn set_return_is_null(&mut self) -> &mut bool

Accessor for the “is null” flag

Safety

If this flag is set to “false”, then the resulting return must be a valid Datum for the function call’s result type.

pub fn return_null(&mut self) -> Datum<'fcx>

Modifies the function call’s return to be null

Returns a null-pointer Datum for use as the calling function’s return value.

If this flag is set, regardless of what your function actually returns, Postgres will presume it is null and discard it. This means that, if you call this method and then return a value anyway, your extension will leak memory. Please ensure this method is only called for functions which, very definitely, return null.

Examples

use pgrx::callconv::FcInfo;
use pgrx::datum::Datum;
use pgrx::prelude::*;
fn foo<'a>(mut fcinfo: FcInfo<'a>) -> Datum<'a> {
    unsafe { fcinfo.return_null() }
}

pub unsafe fn return_raw_datum(&mut self, datum: Datum) -> Datum<'fcx>

Set the return to be non-null and assign a raw Datum the correct lifetime.

Safety

• If the function call expects a by-reference return, and the pg_sys::Datum does not point to a valid object of the correct type, this is undefined behavior.
• If the function call expects a by-reference return, and the pg_sys::Datum points to an object that will not last for the caller’s lifetime, this is undefined behavior.
• If the function call expects a by-value return, and the pg_sys::Datum is not a valid instance of that type when interpreted as such, this is undefined behavior.
• If the return must be the SQL null, then calling this function is undefined behavior.

Functionally, this can be thought of as a convenience for a mem::transmute from pg_sys::Datum to pgrx::datum::Datum<'fcx>. This gives it similar constraints.

pub fn get_collation(&self) -> Option<Oid>

Get the collation the function call should use. If the OID is 0 (invalid or no-type) this method will return None, otherwise it will return Some(oid).

pub fn get_arg_type(&self, num: usize) -> Option<Oid>

Retrieve the type (as an Oid) of argument number num. In other words, the type of self.raw_args()[num]

pub fn get_or_init_func_extra<DefaultValue: FnOnce() -> *mut FuncCallContext>( &self, default: DefaultValue, ) -> NonNull<FuncCallContext>

Retrieve the .flinfo.fn_extra pointer (as a PgBox’d type) from pg_sys::FunctionCallInfo. If it was not already initialized, initialize it with default

pub fn srf_is_initialized(&self) -> bool

pub unsafe fn init_multi_func_call(&mut self) -> &'fcx mut FuncCallContext

Thin wrapper around pg_sys::init_MultiFuncCall, made necessary because this structure’s FunctionCallInfo is a private field.

This should initialize self.0.flinfo.fn_extra

pub unsafe fn srf_return_next(&mut self)

Safety: Assumes self.0.flinfo.fn_extra is non-null i.e. FcInfo::srf_is_initialized() would be true.

pub unsafe fn srf_return_done(&mut self)

Safety: Assumes self.0.flinfo.fn_extra is non-null i.e. FcInfo::srf_is_initialized() would be true.

pub unsafe fn get_result_info(&self) -> ReturnSetInfoWrapper<'fcx>

Safety

Do not corrupt the pg_sys::ReturnSetInfo struct’s data.

pub fn args<'arg>(&'arg self) -> Args<'arg, 'fcx>

Trait Implementations

impl<'fcx> Clone for FcInfo<'fcx>

fn clone(&self) -> FcInfo<'fcx>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.