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#![allow(dead_code)]
use sqlx::database::HasArguments;
use sqlx::encode::Encode;
use sqlx::types::Type;
use sqlx::{Arguments, Database};
use std::fmt::Display;
pub struct UpdateBuilder<'args, DB>
where
DB: Database,
{
table: Option<String>,
names: Option<Vec<(String, String)>>,
where_: Option<Vec<(String, String, String)>>,
values: Option<<DB as HasArguments<'args>>::Arguments>,
}
impl<'args, DB: Database> UpdateBuilder<'args, DB>
where
DB: Database,
{
pub fn new() -> Self
where
<DB as HasArguments<'args>>::Arguments: Default,
{
UpdateBuilder {
table: None,
names: Some(Vec::new()),
where_: Some(Vec::new()),
values: Some(Default::default()),
}
}
#[inline]
fn sanity_check(&self) {
assert!(
self.values.is_some(),
"UpdateBuilder must be reset before reuse after `.build()`"
);
}
pub fn table(&mut self, table: impl Display) -> &mut Self {
self.sanity_check();
self.table = Some(format!("{table}"));
self
}
pub fn and_where<T>(&mut self, name: impl Display, op: impl Display, value: T) -> &mut Self
where
T: 'args + Encode<'args, DB> + Send + Type<DB>,
{
self.sanity_check();
let values = self.values.as_mut().expect("BUG: Values taken already");
values.add(value);
let mut placeholder = String::new();
values
.format_placeholder(&mut placeholder)
.expect("error in format_placeholder");
let where_ = self.where_.as_mut().expect("BUG: Where taken already");
where_.push((format!("{name}"), format!("{op}"), placeholder));
self
}
pub fn set<T>(&mut self, name: impl Display, value: T) -> &mut Self
where
T: 'args + Encode<'args, DB> + Send + Type<DB>,
{
self.sanity_check();
assert!(
self.where_.as_ref().unwrap().is_empty(),
"set must not be called after add_where"
);
let names = self.names.as_mut().expect("BUG: Names taken already");
let values = self.values.as_mut().expect("BUG: Values taken already");
values.add(value);
let mut placeholder = String::new();
values
.format_placeholder(&mut placeholder)
.expect("error in format_placeholder");
names.push((format!("{name}"), placeholder));
self
}
pub fn build(&mut self) -> (String, <DB as HasArguments<'args>>::Arguments) {
self.sanity_check();
let table = self.table.take().unwrap();
let mut query = format!("UPDATE {table} SET");
let mut first = true;
for (name, placeholder) in self.names.take().unwrap() {
if first {
first = false;
} else {
query.push(',');
}
query.push_str(&format!(" {name}={placeholder}"));
}
let where_ = self.where_.take().unwrap();
if !where_.is_empty() {
query.push_str(" WHERE");
first = true;
for (name, op, placeholder) in where_ {
if first {
first = false;
} else {
query.push_str(" AND");
}
query.push_str(&format!(" {name}{op}{placeholder}"));
}
}
// TODO: This method should return a Query, constructed by QueryBuilder, but I can't
// figure out how to create QueryBuilder::with_arguments in this generic method,
// where DB isn't "known".
(query, self.values.take().unwrap())
}
pub fn reset(&mut self) -> &mut Self {
self.names = Some(Vec::new());
self.where_ = Some(Vec::new());
self.values = Some(Default::default());
self
}
}
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