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Support $this, $args, $ and other $variable expressions.
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@benjamn
benjamn committed May 10, 2024
1 parent 92bdf1d commit df59279
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Showing 3 changed files with 398 additions and 29 deletions.
136 changes: 120 additions & 16 deletions apollo-federation/src/sources/connect/json_selection/apply_to.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
use std::hash::Hash;
use std::hash::Hasher;

use indexmap::IndexMap;
use indexmap::IndexSet;
use itertools::Itertools;
use serde_json_bytes::json;
Expand All @@ -19,10 +20,18 @@ pub trait ApplyTo {
// explicitly support), which are distinct from null values (which it does
// support).
fn apply_to(&self, data: &JSON) -> (Option<JSON>, Vec<ApplyToError>) {
self.apply_with_vars(data, &IndexMap::new())
}

fn apply_with_vars(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
) -> (Option<JSON>, Vec<ApplyToError>) {
let mut input_path = vec![];
// Using IndexSet over HashSet to preserve the order of the errors.
let mut errors = IndexSet::new();
let value = self.apply_to_path(data, &mut input_path, &mut errors);
let value = self.apply_to_path(data, vars, &mut input_path, &mut errors);
(value, errors.into_iter().collect())
}

Expand All @@ -31,6 +40,7 @@ pub trait ApplyTo {
fn apply_to_path(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON>;
Expand All @@ -40,14 +50,15 @@ pub trait ApplyTo {
fn apply_to_array(
&self,
data_array: &[JSON],
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON> {
let mut output = Vec::with_capacity(data_array.len());

for (i, element) in data_array.iter().enumerate() {
input_path.push(Key::Index(i));
let value = self.apply_to_path(element, input_path, errors);
let value = self.apply_to_path(element, vars, input_path, errors);
input_path.pop();
// When building an Object, we can simply omit missing properties
// and report an error, but when building an Array, we need to
Expand Down Expand Up @@ -129,11 +140,12 @@ impl ApplyTo for JSONSelection {
fn apply_to_path(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON> {
let data = match data {
JSON::Array(array) => return self.apply_to_array(array, input_path, errors),
JSON::Array(array) => return self.apply_to_array(array, vars, input_path, errors),
JSON::Object(_) => data,
_ => {
errors.insert(ApplyToError::new("not an object", input_path));
Expand All @@ -149,9 +161,11 @@ impl ApplyTo for JSONSelection {
// need to create a temporary SubSelection to wrap the selections
// Vec.
Self::Named(named_selections) => {
named_selections.apply_to_path(data, input_path, errors)
named_selections.apply_to_path(data, vars, input_path, errors)
}
Self::Path(path_selection) => {
path_selection.apply_to_path(data, vars, input_path, errors)
}
Self::Path(path_selection) => path_selection.apply_to_path(data, input_path, errors),
}
}
}
Expand All @@ -160,11 +174,12 @@ impl ApplyTo for NamedSelection {
fn apply_to_path(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON> {
let data = match data {
JSON::Array(array) => return self.apply_to_array(array, input_path, errors),
JSON::Array(array) => return self.apply_to_array(array, vars, input_path, errors),
JSON::Object(_) => data,
_ => {
errors.insert(ApplyToError::new("not an object", input_path));
Expand All @@ -184,7 +199,7 @@ impl ApplyTo for NamedSelection {
if let Some(child) = data.get(name) {
let output_name = alias.map_or(name, |alias| &alias.name);
if let Some(selection) = selection {
let value = selection.apply_to_path(child, input_path, errors);
let value = selection.apply_to_path(child, vars, input_path, errors);
if let Some(value) = value {
output.insert(output_name.clone(), value);
}
Expand All @@ -211,13 +226,13 @@ impl ApplyTo for NamedSelection {
input_path.pop();
}
Self::Path(alias, path_selection) => {
let value = path_selection.apply_to_path(data, input_path, errors);
let value = path_selection.apply_to_path(data, vars, input_path, errors);
if let Some(value) = value {
output.insert(alias.name.clone(), value);
}
}
Self::Group(alias, sub_selection) => {
let value = sub_selection.apply_to_path(data, input_path, errors);
let value = sub_selection.apply_to_path(data, vars, input_path, errors);
if let Some(value) = value {
output.insert(alias.name.clone(), value);
}
Expand All @@ -232,14 +247,31 @@ impl ApplyTo for PathSelection {
fn apply_to_path(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON> {
if let JSON::Array(array) = data {
return self.apply_to_array(array, input_path, errors);
return self.apply_to_array(array, vars, input_path, errors);
}

match self {
Self::Var(var_name, tail) => {
if var_name == "$" {
// Because $ refers to the current value, we keep using
// input_path instead of creating a new var_path here.
tail.apply_to_path(data, vars, input_path, errors)
} else if let Some(var_data) = vars.get(var_name) {
let mut var_path = vec![Key::Field(var_name.clone())];
tail.apply_to_path(var_data, vars, &mut var_path, errors)
} else {
errors.insert(ApplyToError::new(
format!("Variable {} not found", var_name).as_str(),
&[Key::Field(var_name.clone())],
));
None
}
}
Self::Key(key, tail) => {
match data {
JSON::Object(_) => {}
Expand All @@ -262,7 +294,7 @@ impl ApplyTo for PathSelection {
Key::Quoted(name) => data.get(name),
Key::Index(index) => data.get(index),
} {
let result = tail.apply_to_path(child, input_path, errors);
let result = tail.apply_to_path(child, vars, input_path, errors);
input_path.pop();
result
} else {
Expand All @@ -279,7 +311,7 @@ impl ApplyTo for PathSelection {
Self::Selection(selection) => {
// If data is not an object here, this recursive apply_to_path
// call will handle the error.
selection.apply_to_path(data, input_path, errors)
selection.apply_to_path(data, vars, input_path, errors)
}
Self::Empty => {
// If data is not an object here, we want to preserve its value
Expand All @@ -294,11 +326,12 @@ impl ApplyTo for SubSelection {
fn apply_to_path(
&self,
data: &JSON,
vars: &IndexMap<String, JSON>,
input_path: &mut Vec<Key>,
errors: &mut IndexSet<ApplyToError>,
) -> Option<JSON> {
let data_map = match data {
JSON::Array(array) => return self.apply_to_array(array, input_path, errors),
JSON::Array(array) => return self.apply_to_array(array, vars, input_path, errors),
JSON::Object(data_map) => data_map,
_ => {
errors.insert(ApplyToError::new(
Expand All @@ -317,7 +350,7 @@ impl ApplyTo for SubSelection {
let mut input_names = IndexSet::new();

for named_selection in &self.selections {
let value = named_selection.apply_to_path(data, input_path, errors);
let value = named_selection.apply_to_path(data, vars, input_path, errors);

// If value is an object, extend output with its keys and their values.
if let Some(JSON::Object(key_and_value)) = value {
Expand Down Expand Up @@ -378,7 +411,9 @@ impl ApplyTo for SubSelection {
let mut star_output = Map::new();
for (key, value) in data_map {
if !input_names.contains(key.as_str()) {
if let Some(selected) = selection.apply_to_path(value, input_path, errors) {
if let Some(selected) =
selection.apply_to_path(value, vars, input_path, errors)
{
star_output.insert(key.clone(), selected);
}
}
Expand All @@ -389,7 +424,9 @@ impl ApplyTo for SubSelection {
Some(StarSelection(None, Some(selection))) => {
for (key, value) in data_map {
if !input_names.contains(key.as_str()) {
if let Some(selected) = selection.apply_to_path(value, input_path, errors) {
if let Some(selected) =
selection.apply_to_path(value, vars, input_path, errors)
{
output.insert(key.clone(), selected);
}
}
Expand Down Expand Up @@ -1041,6 +1078,73 @@ mod tests {
);
}

#[test]
fn test_apply_to_variable_expressions() {
let id_object = selection!("id: $").apply_to(&json!(123));
assert_eq!(id_object, (Some(json!({"id": 123})), vec![]));

let data = json!({
"id": 123,
"name": "Ben",
"friend_ids": [234, 345, 456]
});

assert_eq!(
selection!("id name friends: friend_ids { id: $ }").apply_to(&data),
(
Some(json!({
"id": 123,
"name": "Ben",
"friends": [
{ "id": 234 },
{ "id": 345 },
{ "id": 456 },
],
})),
vec![],
),
);

let mut vars = IndexMap::new();
vars.insert("$args".to_string(), json!({ "id": "id from args" }));
assert_eq!(
selection!("id: $args.id name").apply_with_vars(&data, &vars),
(
Some(json!({
"id": "id from args",
"name": "Ben"
})),
vec![],
),
);
assert_eq!(
selection!("id: $args.id name").apply_to(&data),
(
Some(json!({
"name": "Ben"
})),
vec![ApplyToError::from_json(&json!({
"message": "Variable $args not found",
"path": ["$args"],
}))],
),
);
let mut vars_without_args_id = IndexMap::new();
vars_without_args_id.insert("$args".to_string(), json!({ "unused": "ignored" }));
assert_eq!(
selection!("id: $args.id name").apply_with_vars(&data, &vars_without_args_id),
(
Some(json!({
"name": "Ben"
})),
vec![ApplyToError::from_json(&json!({
"message": "Property .id not found in object",
"path": ["$args", "id"],
}))],
),
);
}

#[test]
fn test_apply_to_non_identifier_properties() {
let data = json!({
Expand Down
4 changes: 4 additions & 0 deletions apollo-federation/src/sources/connect/json_selection/graphql.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,10 @@ impl From<NamedSelection> for Vec<GraphQLSelection> {
impl From<PathSelection> for Vec<GraphQLSelection> {
fn from(val: PathSelection) -> Vec<GraphQLSelection> {
match val {
PathSelection::Var(_, _) => {
// Variable references do not correspond to GraphQL fields.
vec![]
}
PathSelection::Key(_, tail) => {
let tail = *tail;
tail.into()
Expand Down
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