Deduping of new variable definitions when delegating to schemas (#607)

* add tests demonstrating bug with var generation * add deduping of new variable definitions when delegating to schemas * update changelog.md
ardatan · Feb 5, 2018 · 90838c1 · 90838c1
1 parent 2868fe2
commit 90838c1
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Change log
 
 ### vNEXT
+* Fix `delegateToSchema.ts` to remove duplicate new variable definitions when delegating to schemas [PR #607](https://github.com/apollographql/graphql-tools/pull/607)
 
 ### v2.19.1
 * Fix duplicate subscriptions for schema stitching [PR #609](https://github.com/apollographql/graphql-tools/pull/609)

diff --git a/src/stitching/delegateToSchema.ts b/src/stitching/delegateToSchema.ts
@@ -139,14 +139,17 @@ export function createDocument(
       }
     }),
   };
-
-  const newVariableDefinitions = newVariables.map(({ arg, variable }) => {
+  const newVariableDefinitions: VariableDefinitionNode[] = [];
+  newVariables.forEach(({ arg, variable }) => {
+    if (newVariableDefinitions.find(newVarDef => newVarDef.variable.name.value === variable)) {
+      return;
+    }
     const argDef = rootField.args.find(rootArg => rootArg.name === arg);
     if (!argDef) {
       throw new Error('Unexpected missing arg');
     }
     const typeName = typeToAst(argDef.type);
-    return {
+    newVariableDefinitions.push({
       kind: Kind.VARIABLE_DEFINITION,
       variable: {
         kind: Kind.VARIABLE,
@@ -156,7 +159,7 @@ export function createDocument(
         },
       },
       type: typeName,
-    };
+    });
   });
 
   const {
@@ -179,7 +182,7 @@ export function createDocument(
         variableDefinition =>
           usedVariables.indexOf(variableDefinition.variable.name.value) !== -1,
       ),
-      ...newVariableDefinitions,
+      ...newVariableDefinitions
     ],
     selectionSet,
   };