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use crate::{
error::TitoError,
types::{FieldValue, TitoEngine, TitoModelTrait, TitoRelationshipConfig},
TitoModel,
};
use serde::{de::DeserializeOwned, Serialize};
use serde_json::Value;
use std::collections::HashMap;
impl<
E: TitoEngine,
T: Default
+ Clone
+ Serialize
+ DeserializeOwned
+ Unpin
+ std::marker::Send
+ Sync
+ TitoModelTrait,
> TitoModel<E, T>
{
/// Public entry point for stitching a relationship into a JSON Value.
pub fn stitch_relationship(
&self,
item: &mut Value,
rel_map: &HashMap<String, Value>,
config: &TitoRelationshipConfig,
) {
let source_parts: Vec<&str> = config.source_field_name.split('.').collect();
let dest_parts: Vec<&str> = config.destination_field_name.split('.').collect();
// Calls the robust iterative helper function.
Self::_stitch_iterative_helper(item, &source_parts, &dest_parts, rel_map, config);
}
/// Iteratively traverses a JSON structure to embed related data, avoiding recursion.
fn _stitch_iterative_helper(
root_node: &mut Value,
source_path: &[&str],
dest_path: &[&str],
rel_map: &HashMap<String, Value>,
config: &TitoRelationshipConfig,
) {
// Use a stack to manage traversal, mimicking a recursive call stack safely.
let mut stack: Vec<(&mut Value, &[&str], &[&str])> = Vec::new();
stack.push((root_node, source_path, dest_path));
while let Some((current_node, source_path_remaining, dest_path_remaining)) = stack.pop() {
// Base case: We've reached the target object for stitching.
if source_path_remaining.len() == 1 && dest_path_remaining.len() == 1 {
let source_key = source_path_remaining[0];
let dest_key = dest_path_remaining[0];
if let Some(obj_to_modify) = current_node.as_object_mut() {
if let Some(id_val_at_source_key) = obj_to_modify.get(source_key) {
// Handle a single ID string.
if let Some(id_str) = id_val_at_source_key.as_str() {
let rel_lookup_key = format!("table:{}:{}", config.model, id_str);
if let Some(related_data) = rel_map.get(&rel_lookup_key) {
obj_to_modify.insert(dest_key.to_string(), related_data.clone());
}
// Handle an array of ID strings.
} else if let Some(ids_array) = id_val_at_source_key.as_array() {
let mut stitched_related_items_array = Vec::new();
for id_elem_in_array in ids_array {
if let Some(id_str_elem) = id_elem_in_array.as_str() {
let rel_lookup_key =
format!("table:{}:{}", config.model, id_str_elem);
if let Some(related_data) = rel_map.get(&rel_lookup_key) {
stitched_related_items_array.push(related_data.clone());
}
}
}
obj_to_modify.insert(
dest_key.to_string(),
Value::Array(stitched_related_items_array),
);
}
}
}
continue; // Finished with this branch, process next item on stack.
}
// Traversal step: Navigate deeper if paths have a common prefix.
if !source_path_remaining.is_empty()
&& !dest_path_remaining.is_empty()
&& source_path_remaining[0] == dest_path_remaining[0]
{
let common_key = source_path_remaining[0];
if let Some(next_node_candidate) = current_node.get_mut(common_key) {
match next_node_candidate {
Value::Object(_) => {
stack.push((
next_node_candidate,
&source_path_remaining[1..],
&dest_path_remaining[1..],
));
}
Value::Array(arr) => {
// If it's an array, push each element onto the stack to be processed.
for element_in_array in arr.iter_mut() {
stack.push((
element_in_array,
&source_path_remaining[1..],
&dest_path_remaining[1..],
));
}
}
_ => {} // Not an object or array, cannot traverse further down this path.
}
}
}
}
}
/// Gathers all relationship keys that need to be fetched from a list of items.
pub fn get_relationship_data(
&self,
items: &Vec<(String, Value)>,
rels_config: &[TitoRelationshipConfig],
rels: &Vec<String>, // List of destination_field_names to populate
) -> Vec<(TitoRelationshipConfig, String)> {
let mut relationship_keys_to_fetch = Vec::new();
for (_, item_value) in items {
for config in rels_config {
// Check if this relationship is requested for population.
if rels.contains(&config.destination_field_name) {
if let Some(found_values_at_source_path) =
self.get_nested_values(item_value, &config.source_field_name)
{
for field_value in found_values_at_source_path {
// Extract the actual value from FieldValue enum
let actual_value = match field_value {
FieldValue::Simple(v) => v,
FieldValue::HashMapEntry { value, .. } => value,
};
if let Some(id_str) = actual_value.as_str() {
if id_str != "__null__" {
relationship_keys_to_fetch.push((
config.clone(),
format!("table:{}:{}", config.model, id_str),
));
}
} else if let Some(id_array) = actual_value.as_array() {
for id_element in id_array {
if let Some(id_str) = id_element.as_str() {
if id_str != "__null__" {
relationship_keys_to_fetch.push((
config.clone(),
format!("table:{}:{}", config.model, id_str),
));
}
}
}
}
}
}
}
}
}
relationship_keys_to_fetch
}
/// Fetches and stitches all requested relationships for a vector of items.
pub async fn fetch_and_stitch_relationships(
&self,
items: Vec<(String, Value)>,
rels: Vec<String>,
tx: &E::Transaction,
) -> Result<Vec<(String, Value)>, TitoError> {
if rels.is_empty() {
return Ok(items);
}
let rels_config = self.relationships();
let relationship_data = self.get_relationship_data(&items, &rels_config, &rels);
let rel_keys: Vec<String> = relationship_data.into_iter().map(|item| item.1).collect();
// Fetch all related items in a batch.
let rel_items = self.batch_get(rel_keys, 10, 2, tx).await?;
let mut rel_map: HashMap<String, Value> = HashMap::new();
for kv in rel_items {
rel_map.insert(kv.0, kv.1);
}
// Map over the original items and stitch the fetched data into each one.
let final_items = items
.into_iter()
.map(|mut item| {
for config in &rels_config {
if rels.contains(&config.destination_field_name) {
self.stitch_relationship(&mut item.1, &rel_map, config);
}
}
item
})
.collect();
Ok(final_items)
}
/// A helper function to extract a relationship string.
pub fn extract_relationship(&self, input: &str) -> Option<String> {
if let (Some(start), Some(end)) = (input.find('-').map(|idx| idx + 1), input.rfind('-')) {
if start < end {
return Some(input[start..end].trim().to_string());
}
}
None
}
}