handle graphql exists type

src/graphql/schema/withOperators.js

@@ -1,23 +1,30 @@
-const { GraphQLList, GraphQLInputObjectType } = require('graphql');
+const { GraphQLList, GraphQLInputObjectType, GraphQLBoolean } = require('graphql');
 const combineParentName = require('../utilities/combineParentName');
 
 const withOperators = (field, type, parent, operators) => {
   const name = `${combineParentName(parent, field.name)}_operator`;
   const listOperators = ['in', 'not_in', 'all'];
 
-  if (!field.required) {
-    console.log('name', field.name);
-    operators.push('exists');
-  }
+  if (!field.required) operators.push('exists');
 
   return new GraphQLInputObjectType({
     name,
-    fields: operators.reduce((fields, operator) => ({
-      ...fields,
-      [operator]: {
-        type: listOperators.indexOf(operator) > -1 ? new GraphQLList(type) : type,
-      },
-    }), {}),
+    fields: operators.reduce((fields, operator) => {
+      let gqlType;
+      if (listOperators.indexOf(operator) > -1) {
+        gqlType = new GraphQLList(type);
+      } else if (operator === 'exists') {
+        gqlType = GraphQLBoolean;
+      } else {
+        gqlType = type;
+      }
+      return {
+        ...fields,
+        [operator]: {
+          type: gqlType,
+        },
+      };
+    }, {}),
   });
 };