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use super::Schema;
use crate::{
extension::{JsonObjectExt, JsonValueExt},
model::EncodeColumn,
JsonValue, Map, SharedString,
};
use std::{borrow::Cow, fmt::Display};
/// Extension trait for [`Query`](crate::model::Query).
pub(super) trait QueryExt<DB> {
/// Query result type.
type QueryResult;
/// Parses the query result to get `last_insert_id` and `rows_affected`.
fn parse_query_result(query_result: Self::QueryResult) -> (Option<i64>, u64);
/// Returns a reference to the projection fields.
fn query_fields(&self) -> &[String];
/// Returns a reference to the filters.
fn query_filters(&self) -> ⤅
/// Returns the sort order.
fn query_order(&self) -> &[(SharedString, bool)];
/// Returns the query offset.
fn query_offset(&self) -> usize;
/// Returns the query limit.
fn query_limit(&self) -> usize;
/// Returns a placeholder for the n-th parameter.
fn placeholder(n: usize) -> SharedString;
/// Prepares the SQL query for binding parameters.
fn prepare_query<'a>(
query: &'a str,
params: Option<&'a Map>,
) -> (Cow<'a, str>, Vec<&'a JsonValue>);
/// Formats a field for the query.
fn format_field(field: &str) -> Cow<'_, str>;
/// Formats table fields.
fn format_table_fields<M: Schema>(&self) -> Cow<'_, str>;
/// Formats the table name.
fn format_table_name<M: Schema>(&self) -> String;
/// Parses text search filter.
fn parse_text_search(filter: &Map) -> Option<String>;
/// Escapes a string.
#[inline]
fn escape_string(value: impl Display) -> String {
format!("'{}'", value.to_string().replace('\'', "''"))
}
/// Formats projection fields.
fn format_projection(&self) -> Cow<'_, str> {
let fields = self.query_fields();
if fields.is_empty() {
"*".into()
} else {
fields
.iter()
.map(|field| {
if let Some((alias, expr)) = field.split_once(':') {
let alias = Self::format_field(alias.trim());
format!(r#"{expr} AS {alias}"#).into()
} else {
Self::format_field(field)
}
})
.collect::<Vec<_>>()
.join(", ")
.into()
}
}
/// Formats the query filters to generate SQL `WHERE` expression.
fn format_filters<M: Schema>(&self) -> String {
let filters = self.query_filters();
if filters.is_empty() {
return String::new();
}
let mut expression = String::new();
let mut conditions = Vec::with_capacity(filters.len());
for (key, value) in filters {
match key.as_str() {
"$and" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " AND ");
conditions.push(condition);
}
}
"$not" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " AND ");
conditions.push(format!("(NOT {condition})"));
}
}
"$or" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " OR ");
conditions.push(condition);
}
}
"$rand" => {
if let Some(Ok(value)) = value.parse_f64() {
let condition = if cfg!(any(
feature = "orm-mariadb",
feature = "orm-mysql",
feature = "orm-tidb"
)) {
format!("rand() < {value}")
} else if cfg!(feature = "orm-postgres") {
format!("random() < {value}")
} else {
let value = (value * i64::MAX as f64) as i64;
format!("abs(random()) < {value}")
};
conditions.push(condition);
}
}
"$text" => {
if let Some(value) = value.as_object() {
if let Some(condition) = Self::parse_text_search(value) {
conditions.push(condition);
}
}
}
"$ovlp" => {
if let Some(value) = value.parse_str_array()
&& let &[start_field, end_field, start_value, end_value] = value.as_slice()
{
let start_field = Self::format_field(start_field);
let end_field = Self::format_field(end_field);
let start_value = Self::escape_string(start_value);
let end_value = Self::escape_string(end_value);
let condition = if cfg!(any(
feature = "orm-mariadb",
feature = "orm-mysql",
feature = "orm-tidb"
)) {
format!(
r#"overlaps({start_field}, {end_field}, {start_value}, {end_value})"#
)
} else if cfg!(feature = "orm-postgres") {
format!(
r#"({start_field}, {end_field}) OVERLAPS ({start_value}, {end_value})"#
)
} else {
format!(
r#"({start_field} <= {end_value} AND {end_field} >= {start_value})"#
)
};
conditions.push(condition);
}
}
_ => {
if let Some(col) = M::get_column(key) {
let condition = col.format_filter(key, value);
if !condition.is_empty() {
conditions.push(condition);
}
} else if key.contains('.') {
let condition = Self::format_filter(key, value);
if !condition.is_empty() {
conditions.push(condition);
}
}
}
}
}
if !conditions.is_empty() {
expression += &format!("WHERE {}", conditions.join(" AND "));
};
if let Some(groups) = filters.parse_str_array("$group") {
let groups = groups
.into_iter()
.map(Self::format_field)
.collect::<Vec<_>>()
.join(", ");
expression += &format!(" GROUP BY {groups}");
if let Some(filters) = filters.get_array("$having") {
let condition = Self::format_logical_filters::<M>(filters, " AND ");
expression += &format!(" HAVING {condition}");
}
}
expression
}
// Formats the filters with a logic operator.
fn format_logical_filters<M: Schema>(filters: &[JsonValue], operator: &str) -> String {
let mut conditions = Vec::with_capacity(filters.len());
for filter in filters {
if let JsonValue::Object(filter) = filter {
for (key, value) in filter {
match key.as_str() {
"$and" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " AND ");
conditions.push(condition);
}
}
"$not" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " AND ");
conditions.push(format!("(NOT {condition})"));
}
}
"$nor" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " OR ");
conditions.push(format!("(NOT {condition})"));
}
}
"$or" => {
if let Some(filters) = value.as_array() {
let condition = Self::format_logical_filters::<M>(filters, " OR ");
conditions.push(condition);
}
}
"$ovlp" => {
if let Some(value) = value.parse_str_array()
&& let &[start_field, end_field, start_value, end_value] =
value.as_slice()
{
let start_field = Self::format_field(start_field);
let end_field = Self::format_field(end_field);
let start_value = Self::escape_string(start_value);
let end_value = Self::escape_string(end_value);
let condition = if cfg!(any(
feature = "orm-mariadb",
feature = "orm-mysql",
feature = "orm-tidb"
)) {
format!(
r#"overlaps({start_field}, {end_field}, {start_value}, {end_value})"#
)
} else if cfg!(feature = "orm-postgres") {
format!(
r#"({start_field}, {end_field}) OVERLAPS ({start_value}, {end_value})"#
)
} else {
format!(
r#"({start_field} <= {end_value} AND {end_field} >= {start_value})"#
)
};
conditions.push(condition);
}
}
_ => {
if let Some(col) = M::get_column(key) {
let condition = col.format_filter(key, value);
if !condition.is_empty() {
conditions.push(condition);
}
} else if key.contains('.') {
let condition = Self::format_filter(key, value);
if !condition.is_empty() {
conditions.push(condition);
}
}
}
}
}
}
}
if conditions.is_empty() {
String::new()
} else {
format!("({})", conditions.join(operator))
}
}
/// Formats a query filter.
fn format_filter(key: &str, value: &JsonValue) -> String {
if let Some(filter) = value.as_object() {
let mut conditions = Vec::with_capacity(filter.len());
for (name, value) in filter {
if let Some(value) = value.parse_string() {
let operator = match name.as_str() {
"$eq" => "=",
"$ne" => "<>",
"$lt" => "<",
"$le" => "<=",
"$gt" => ">",
"$ge" => ">=",
_ => "=",
};
let field = Self::format_field(key);
let value = Self::escape_string(value);
let condition = format!(r#"{field} {operator} {value}"#);
conditions.push(condition);
}
}
if conditions.is_empty() {
String::new()
} else {
format!("({})", conditions.join(" AND "))
}
} else if let Some(value) = value.parse_string() {
let key = Self::format_field(key);
let value = Self::escape_string(value);
format!(r#"{key} = {value}"#)
} else {
String::new()
}
}
/// Formats the query sort to generate SQL `ORDER BY` expression.
fn format_sort(&self) -> String {
let sort_order = self.query_order();
if sort_order.is_empty() {
String::new()
} else {
let sort_order = sort_order
.iter()
.map(|(sort, descending)| {
if *descending {
format!("{sort} DESC")
} else {
format!("{sort} ASC")
}
})
.collect::<Vec<_>>();
format!("ORDER BY {}", sort_order.join(", "))
}
}
/// Formats the query pagination to generate SQL `LIMIT` expression.
fn format_pagination(&self) -> String {
let limit = self.query_limit();
if limit == 0 || limit == usize::MAX {
return String::new();
}
let offset = self.query_offset();
format!("LIMIT {limit} OFFSET {offset}")
}
}