graph, graphql: Resolve variables before executing query

Author: lutter

graph/src/data/graphql/mod.rs

@@ -31,3 +31,4 @@ pub use object_or_interface::ObjectOrInterface;
 pub mod object_macro;
 pub use crate::object;
 pub use object_macro::{object_value, IntoValue};
+pub mod visitor;

graph/src/data/value.rs

@@ -5,7 +5,7 @@ use std::collections::BTreeMap;
 use std::convert::TryFrom;
 use std::iter::FromIterator;
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Clone, PartialEq)]
 pub struct Object(BTreeMap<String, Value>);
 
 impl Object {
@@ -76,6 +76,12 @@ impl Default for Object {
     }
 }
 
+impl std::fmt::Debug for Object {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum Value {
     Int(i64),

graph/src/lib.rs

@@ -184,7 +184,7 @@ pub mod prelude {
     static_graphql!(q, query, {
         Document, Value, OperationDefinition, InlineFragment, TypeCondition,
         FragmentSpread, Field, Selection, SelectionSet, FragmentDefinition,
-        Directive, VariableDefinition, Type,
+        Directive, VariableDefinition, Type, Query,
     });
     static_graphql!(s, schema, {
         Field, Directive, InterfaceType, ObjectType, Value, TypeDefinition,

graphql/src/execution/query.rs

@@ -18,6 +18,7 @@ use graph::data::schema::ApiSchema;
 use graph::prelude::{info, o, q, r, s, BlockNumber, CheapClone, Logger, TryFromValue};
 
 use crate::introspection::introspection_schema;
+use crate::query::ext::ValueExt;
 use crate::query::{ast as qast, ext::BlockConstraint};
 use crate::schema::ast as sast;
 use crate::{
@@ -214,7 +215,7 @@ impl Query {
         let start = Instant::now();
         // Use an intermediate struct so we can modify the query before
         // enclosing it in an Arc
-        let raw_query = RawQuery {
+        let mut raw_query = RawQuery {
             schema,
             variables,
             selection_set,
@@ -226,6 +227,7 @@ impl Query {
         // overflow from invalid queries.
         let complexity = raw_query.check_complexity(max_complexity, max_depth)?;
         raw_query.validate_fields()?;
+        raw_query.expand_variables()?;
 
         let query = Self {
             schema: raw_query.schema,
@@ -726,4 +728,97 @@ impl RawQuery {
                 errors
             })
     }
+
+    fn expand_variables(&mut self) -> Result<(), QueryExecutionError> {
+        fn expand_field(
+            field: &mut q::Field,
+            vars: &HashMap<String, r::Value>,
+        ) -> Result<(), QueryExecutionError> {
+            expand_arguments(&mut field.arguments, &field.position, vars)?;
+            expand_directives(&mut field.directives, vars)?;
+            expand_selection_set(&mut field.selection_set, vars)
+        }
+
+        fn expand_selection_set(
+            set: &mut q::SelectionSet,
+            vars: &HashMap<String, r::Value>,
+        ) -> Result<(), QueryExecutionError> {
+            for sel in &mut set.items {
+                match sel {
+                    q::Selection::Field(field) => expand_field(field, vars)?,
+                    q::Selection::FragmentSpread(spread) => {
+                        expand_directives(&mut spread.directives, vars)?;
+                    }
+                    q::Selection::InlineFragment(frag) => {
+                        expand_directives(&mut frag.directives, vars)?;
+                        expand_selection_set(&mut frag.selection_set, vars)?;
+                    }
+                }
+            }
+            Ok(())
+        }
+
+        fn expand_directives(
+            dirs: &mut Vec<q::Directive>,
+            vars: &HashMap<String, r::Value>,
+        ) -> Result<(), QueryExecutionError> {
+            for dir in dirs {
+                expand_arguments(&mut dir.arguments, &dir.position, vars)?;
+            }
+            Ok(())
+        }
+
+        fn expand_arguments(
+            args: &mut Vec<(String, q::Value)>,
+            pos: &Pos,
+            vars: &HashMap<String, r::Value>,
+        ) -> Result<(), QueryExecutionError> {
+            for arg in args {
+                expand_value(&mut arg.1, pos, vars)?;
+            }
+            Ok(())
+        }
+
+        fn expand_value(
+            val: &mut q::Value,
+            pos: &Pos,
+            vars: &HashMap<String, r::Value>,
+        ) -> Result<(), QueryExecutionError> {
+            match val {
+                q::Value::Variable(ref var) => {
+                    let newval = match vars.get(var) {
+                        Some(val) => q::Value::from(val.clone()),
+                        None => {
+                            return Err(QueryExecutionError::MissingVariableError(
+                                pos.clone(),
+                                var.to_string(),
+                            ))
+                        }
+                    };
+                    *val = newval;
+                    Ok(())
+                }
+                q::Value::Int(_)
+                | q::Value::Float(_)
+                | q::Value::String(_)
+                | q::Value::Boolean(_)
+                | q::Value::Null
+                | q::Value::Enum(_) => Ok(()),
+                q::Value::List(ref mut vals) => {
+                    for mut val in vals.iter_mut() {
+                        expand_value(&mut val, pos, vars)?;
+                    }
+                    Ok(())
+                }
+                q::Value::Object(obj) => {
+                    for mut val in obj.values_mut() {
+                        expand_value(&mut val, pos, vars)?;
+                    }
+                    Ok(())
+                }
+            }
+        }
+
+        expand_selection_set(&mut self.selection_set, &self.variables)
+    }
 }