use super::TokioPostgresCodeGenerator;
use quote::quote;
impl TokioPostgresCodeGenerator {
pub fn generate_query_opt(self) -> proc_macro2::TokenStream {
let TokioPostgresCodeGenerator {
row_type,
error_type,
client_arg_name,
sql_str,
placeholders,
result_columns,
collector_arg: _,
handler_arg: _,
} = self;
let error_type = error_type.unwrap();
let mut parameters = Vec::new();
for placeholder in &placeholders {
let ident = syn::Ident::new(placeholder, proc_macro::Span::call_site().into());
let parameter = quote! { &#ident };
parameters.push(parameter);
}
let mut check_column_names = Vec::new();
let mut set_field_values = Vec::new();
for (index, column) in result_columns.iter().enumerate() {
check_column_names.push(Self::generate_check_column_existing(index, column));
set_field_values.push(Self::generate_set_filed_value(index, column));
}
let result_field_count = check_column_names.len();
quote! {
{
use std::sync::atomic::{AtomicBool, Ordering};
static CHECKED: AtomicBool = AtomicBool::new(false);
if !CHECKED.load(Ordering::Relaxed) {
let statement = #client_arg_name.prepare(#sql_str).await?;
let columns = statement.columns();
if columns.len() != #result_field_count {
Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "result set column count missmatch"))?;
}
#(#check_column_names)*;
CHECKED.store(true, Ordering::Relaxed);
}
let row = #client_arg_name.query_opt(#sql_str, &[#(#parameters),*]).await?;
let mut row_builder = #row_type::builder();
#(#set_field_values)*;
Ok::<_, #error_type>(row_builder.build()?)
}
}
}
}