rustyroad 1.8.6

Rusty Road is a framework written in Rust that is based on Ruby on Rails. It is designed to provide the familiar conventions and ease of use of Ruby on Rails, while also taking advantage of the performance and efficiency of Rust.
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//! Atomic selective updates through verified unique selectors.

use super::super::naming::{pascal, snake, sql};
use super::{patch, selector, targets, where_key};
use crate::database::introspection::{Schema, Table};

/// Emits `update_sessions_by_session_token(pool, key, input)` with a generated Patch.
/// Missing rows return SQLx RowNotFound; an empty patch only looks up the row.
pub(super) fn render(table: &Table, schema: &Schema, key: &[String]) -> (String, bool) {
    let function = format!("update_{}_by_{}", snake(&table.name), targets::suffix(key));
    let model = pascal(&table.name);
    let patch::Patch { parameter, changed, assignments } = patch::render(table, "input");
    let selector::Selector { parameters, predicate, binds, arguments } = selector::update(table, schema, key);
    let select = format!("SELECT * FROM {} WHERE {predicate} LIMIT 1", sql(&table.name));
    let lookup = format!("sqlx::query_as::<_, {model}>({select:?}){binds}.fetch_one(pool).await");
    let builder = !assignments.is_empty();
    let body = if !builder {
        lookup
    } else {
        let prefix = format!("UPDATE {} SET ", sql(&table.name));
        let filter = where_key::render(key);
        format!(
            "    if !({changed}) {{ return {lookup}; }}\n\
                 let mut query = QueryBuilder::<Postgres>::new({prefix:?});\n\
                 {{\n\
                     let mut set = query.separated(\", \");\n\
             {assignments}\n\
                 }}\n\
             {filter}\
                 query.push(\" RETURNING *\");\n\
                 query.build_query_as::<{model}>().fetch_one(pool).await"
        )
    };
    let output = format!(
        "/// Selective update; e.g. `{function}(pool, {arguments}, input).await`.\n\
         /// Unspecified fields remain unchanged; missing rows return SQLx RowNotFound.\n\
         pub async fn {function}(pool: &PgPool, {parameters}, {parameter}) -> Result<{model}, sqlx::Error> {{\n\
         {body}\n\
         }}\n\n"
    );
    (output, builder)
}