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use crate::extensions::{ErrorLogger, ExtensionContext, ResolveInfo};
use crate::parser::types::Selection;
use crate::registry::MetaType;
use crate::{
Context, ContextSelectionSet, Name, OutputValueType, PathSegment, ServerError, ServerResult,
Value,
};
use std::collections::BTreeMap;
use std::future::Future;
use std::pin::Pin;
/// Represents a GraphQL container object.
///
/// This helper trait allows the type to call `resolve_container` on itself in its
/// `OutputValueType::resolve` implementation.
#[async_trait::async_trait]
pub trait ContainerType: OutputValueType {
/// This function returns true of type `EmptyMutation` only.
#[doc(hidden)]
fn is_empty() -> bool {
false
}
/// Resolves a field value and outputs it as a json value `async_graphql::Value`.
///
/// If the field was not found returns None.
async fn resolve_field(&self, ctx: &Context<'_>) -> ServerResult<Option<Value>>;
/// Collect all the fields of the container that are queried in the selection set.
///
/// Objects do not have to override this, but interfaces and unions must call it on their
/// internal type.
fn collect_all_fields<'a>(
&'a self,
ctx: &ContextSelectionSet<'a>,
fields: &mut Fields<'a>,
) -> ServerResult<()>
where
Self: Sized + Send + Sync,
{
fields.add_set(ctx, self)
}
/// Find the GraphQL entity with the given name from the parameter.
///
/// Objects should override this in case they are the query root.
async fn find_entity(&self, _: &Context<'_>, _params: &Value) -> ServerResult<Option<Value>> {
Ok(None)
}
}
#[async_trait::async_trait]
impl<T: ContainerType + Send + Sync> ContainerType for &T {
async fn resolve_field(&self, ctx: &Context<'_>) -> ServerResult<Option<Value>> {
T::resolve_field(*self, ctx).await
}
}
// TODO: reduce code duplication between the two below functions?
/// Resolve an container by executing each of the fields concurrently.
pub async fn resolve_container<'a, T: ContainerType + Send + Sync>(
ctx: &ContextSelectionSet<'a>,
root: &'a T,
) -> ServerResult<Value> {
let mut fields = Fields(Vec::new());
fields.add_set(ctx, root)?;
let futures = fields.0;
let res = futures::future::try_join_all(futures).await?;
let mut map = BTreeMap::new();
for (name, value) in res {
if let Value::Object(b) = value {
if let Some(Value::Object(a)) = map.get_mut(&name) {
a.extend(b);
} else {
map.insert(name, Value::Object(b));
}
} else {
map.insert(name, value);
}
}
Ok(Value::Object(map))
}
/// Resolve an container by executing each of the fields serially.
pub async fn resolve_container_serial<'a, T: ContainerType + Send + Sync>(
ctx: &ContextSelectionSet<'a>,
root: &'a T,
) -> ServerResult<Value> {
let mut fields = Fields(Vec::new());
fields.add_set(ctx, root)?;
let futures = fields.0;
let mut map = BTreeMap::new();
for field in futures {
let (name, value) = field.await?;
if let Value::Object(b) = value {
if let Some(Value::Object(a)) = map.get_mut(&name) {
a.extend(b);
} else {
map.insert(name, Value::Object(b));
}
} else {
map.insert(name, value);
}
}
Ok(Value::Object(map))
}
type BoxFieldFuture<'a> = Pin<Box<dyn Future<Output = ServerResult<(Name, Value)>> + 'a + Send>>;
/// A set of fields on an container that are being selected.
pub struct Fields<'a>(Vec<BoxFieldFuture<'a>>);
impl<'a> Fields<'a> {
/// Add another set of fields to this set of fields using the given container.
pub fn add_set<T: ContainerType + Send + Sync>(
&mut self,
ctx: &ContextSelectionSet<'a>,
root: &'a T,
) -> ServerResult<()> {
for selection in &ctx.item.node.items {
if ctx.is_skip(&selection.node.directives())? {
continue;
}
match &selection.node {
Selection::Field(field) => {
if field.node.name.node == "__typename" {
// Get the typename
let ctx_field = ctx.with_field(field);
let field_name = ctx_field.item.node.response_key().node.clone();
let typename = root.introspection_type_name().into_owned();
self.0.push(Box::pin(async move {
Ok((field_name, Value::String(typename)))
}));
continue;
}
if ctx.is_ifdef(&field.node.directives) {
if let Some(MetaType::Object { fields, .. }) =
ctx.schema_env.registry.types.get(T::type_name().as_ref())
{
if !fields.contains_key(field.node.name.node.as_str()) {
continue;
}
}
}
self.0.push(Box::pin({
// TODO: investigate removing this
let ctx = ctx.clone();
async move {
let ctx_field = ctx.with_field(field);
let field_name = ctx_field.item.node.response_key().node.clone();
let ctx_extension = ExtensionContext {
schema_data: &ctx.schema_env.data,
query_data: &ctx.query_env.ctx_data,
};
if ctx_field.query_env.extensions.is_empty() {
match root.resolve_field(&ctx_field).await {
Ok(value) => Ok((field_name, value.unwrap())),
Err(e) => {
Err(e.path(PathSegment::Field(field_name.to_string())))
}
}
.log_error(&ctx_extension, &ctx_field.query_env.extensions)
} else {
let resolve_info = ResolveInfo {
resolve_id: ctx_field.resolve_id,
path_node: ctx_field.path_node.as_ref().unwrap(),
parent_type: &T::type_name(),
return_type: match ctx_field
.schema_env
.registry
.types
.get(T::type_name().as_ref())
.and_then(|ty| {
ty.field_by_name(field.node.name.node.as_str())
})
.map(|field| &field.ty)
{
Some(ty) => &ty,
None => {
return Err(ServerError::new(format!(
r#"Cannot query field "{}" on type "{}"."#,
field_name,
T::type_name()
))
.at(ctx_field.item.pos)
.path(PathSegment::Field(field_name.to_string())));
}
},
};
ctx_field
.query_env
.extensions
.resolve_start(&ctx_extension, &resolve_info);
let res = match root.resolve_field(&ctx_field).await {
Ok(value) => Ok((field_name, value.unwrap())),
Err(e) => {
Err(e.path(PathSegment::Field(field_name.to_string())))
}
}
.log_error(&ctx_extension, &ctx_field.query_env.extensions)?;
ctx_field
.query_env
.extensions
.resolve_end(&ctx_extension, &resolve_info);
Ok(res)
}
}
}));
}
selection => {
let (type_condition, selection_set) = match selection {
Selection::Field(_) => unreachable!(),
Selection::FragmentSpread(spread) => {
let fragment =
ctx.query_env.fragments.get(&spread.node.fragment_name.node);
let fragment = match fragment {
Some(fragment) => fragment,
None => {
return Err(ServerError::new(format!(
r#"Unknown fragment "{}"."#,
spread.node.fragment_name.node
))
.at(spread.pos));
}
};
(
Some(&fragment.node.type_condition),
&fragment.node.selection_set,
)
}
Selection::InlineFragment(fragment) => (
fragment.node.type_condition.as_ref(),
&fragment.node.selection_set,
),
};
let type_condition =
type_condition.map(|condition| condition.node.on.node.as_str());
let introspection_type_name = root.introspection_type_name();
let applies_concrete_object = type_condition.map_or(false, |condition| {
introspection_type_name == condition
|| ctx
.schema_env
.registry
.implements
.get(&*introspection_type_name)
.map_or(false, |interfaces| interfaces.contains(condition))
});
if applies_concrete_object {
// The fragment applies to the concrete object type.
// TODO: This solution isn't ideal. If there are two interfaces InterfaceA
// and InterfaceB and one type MyObj that implements both, then if you have
// a type condition for `InterfaceA` on an `InterfaceB` and when resolving,
// the `InterfaceB` is actually a `MyObj` then the contents of the fragment
// will be treated as a `MyObj` rather than an `InterfaceB`. Example:
//
// myObjAsInterfaceB {
// ... on InterfaceA {
// # here you can query MyObj fields even when you should only be
// # able to query InterfaceA fields.
// }
// }
root.collect_all_fields(&ctx.with_selection_set(selection_set), self)?;
} else if type_condition.map_or(true, |condition| T::type_name() == condition) {
// The fragment applies to an interface type.
self.add_set(&ctx.with_selection_set(selection_set), root)?;
}
}
}
}
Ok(())
}
}