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/**
* Represent a set of values, a row of results.
*/
#[derive(Clone, Debug)]
pub struct Tuple<'a> {
result: &'a libpq::Result,
index: usize,
}
impl<'a> Tuple<'a> {
pub(crate) fn from(result: &'a libpq::Result, index: usize) -> Self {
Self { result, index }
}
/**
* Retreive the value of field `name` of the tuple.
*
* # Panics
*
* Panics if `n` is greater than or equal to tuple length.
*/
#[must_use]
pub fn get<T>(&self, name: &str) -> T
where
T: crate::FromSql,
{
self.try_get(name)
.unwrap_or_else(|err| panic!("Unable to retreive '{name}' field: {err}"))
}
/**
* Retreive the value of field `name` of the tuple, or `None` if `n` is
* greater than or equal to the length of the tuple.
*/
pub fn try_get<T>(&self, name: &str) -> crate::Result<T>
where
T: crate::FromSql,
{
let n = match self.result.field_number(name) {
Some(n) => n,
None => return Err(crate::Error::MissingField(name.to_string())),
};
self.try_nth(n)
}
/**
* Retreive the nth field.
*
* # Panics
*
* Panics if `n` is greater than or equal to the length of the tuple.
*/
#[must_use]
pub fn nth<T>(&self, n: usize) -> T
where
T: crate::FromSql,
{
self.try_nth(n)
.unwrap_or_else(|err| panic!("Unable to retreive field {n}: {err}"))
}
/**
* Retreive the nth field, or `None` if `n` is greater than or equal to the
* length of the tuple.
*/
pub fn try_nth<T>(&self, n: usize) -> crate::Result<T>
where
T: crate::FromSql,
{
let ty = self.field_type(n);
let format = self.result.field_format(n);
let value = self.result.value(self.index, n);
crate::FromSql::from_sql(&ty, format, value)
}
/**
* Number of field.
*/
#[must_use]
pub fn len(&self) -> usize {
self.result.nfields()
}
/**
* Is the tuple is empty (doesn’t contain field)?
*/
#[must_use]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/**
* Retreive the name of field at position `n`, or `None` if `n` is greater
* than or equal to the length of the tuple.
*/
pub fn field_name(&self, n: usize) -> crate::Result<Option<String>> {
Ok(self.result.field_name(n)?)
}
fn field_type(&self, n: usize) -> crate::pq::Type {
let oid = self.result.field_type(n);
match crate::pq::Type::try_from(oid) {
Ok(ty) => ty,
Err(_) => crate::pq::Type {
oid,
name: "unknow",
descr: "Unknow type",
kind: libpq::types::Kind::Composite,
},
}
}
}