fix: bug with improperly placed discriminators (#1211)

packages/api-explorer/__tests__/__fixtures__/polymorphism/discriminators.json

@@ -72,6 +72,44 @@
           }
         }
       },
+      "/oneOfWithImproperlyPlacedDiscriminator": {
+        "patch": {
+          "summary": "oneOf with a discriminator that is referencing a property up a level",
+          "description": "This is an improper use of discriminators, but we should ignore the discriminator if this happens instead of failing to render the operation.",
+          "requestBody": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "connector_type": {
+                      "type": "string",
+                      "enum": [
+                        "s3Import",
+                        "gcsImport"
+                      ]
+                    },
+                    "connector_properties": {
+                      "type": "object",
+                      "oneOf": [
+                        {
+                          "$ref": "#/components/schemas/gcsImport"
+                        },
+                        {
+                          "$ref": "#/components/schemas/s3Import"
+                        }
+                      ],
+                      "discriminator": {
+                        "propertyName": "connector_type"
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      },
       "/pets": {
         "patch": {
           "summary": "oneOf request with a nested allOf and embedded discriminator",
@@ -359,6 +397,28 @@
               }
             }
           ]
+        },
+        "gcsImport": {
+          "type": "object",
+          "properties": {
+            "gcs_bucket": {
+              "type": "string"
+            },
+            "gcs_prefix": {
+              "type": "string"
+            }
+          }
+        },
+        "s3Import": {
+          "type": "object",
+          "properties": {
+            "s3_bucket": {
+              "type": "string"
+            },
+            "s3_prefix": {
+              "type": "string"
+            }
+          }
         }
       }
     }

packages/api-explorer/__tests__/form-components/MultiSchemaField.test.jsx

@@ -194,4 +194,19 @@ describe('discriminator', () => {
     expect(secondChangeParamsText).toContain('bark');
     expect(secondChangeParamsText).not.toContain('hunts');
   });
+
+  it('should ignore the discriminator if it is improperly placed', async () => {
+    const testOas = new Oas(discriminators);
+    await testOas.dereference();
+    const operation = testOas.operation('/oneOfWithImproperlyPlacedDiscriminator', 'patch');
+    const Params = createParams(oas, operation);
+
+    expect(() => {
+      return mount(
+        <div>
+          <Params {...props} formData={{}} oas={testOas} operation={operation} />
+        </div>
+      );
+    }).not.toThrow("Cannot use 'in' operator to search for '$ref' in null");
+  });
 });

packages/api-explorer/src/form-components/MultiSchemaField.jsx

@@ -241,9 +241,10 @@ class MultiSchemaField extends Component {
     const SchemaField = registry.fields.SchemaField;
     const { selectedIndex, selectedValue, discriminatorSchema, discriminatorFieldSchema, enumOptions } = this.state;
 
-    // We've got a custom path if there's a discriminator, otherwise we fall back ot the old multischema field
-    if (discriminatorSchema) {
-      // Find which schema we wnat to render by looking at the options prop. The order of these options matches the
+    // We've got a custom path if there's a properly-formed discriminator, otherwise we fall back ot the old MultiSchema
+    // field.
+    if (discriminatorFieldSchema && discriminatorSchema) {
+      // Find which schema we want to render by looking at the options prop. The order of these options matches the
       // order of the dropdown options, and so we can just stick with matching indicies.
       const option = options[selectedIndex] || null;
       let optionSchema;