Fix support for using $ref in a component definition

packages/openapi3-parser/CHANGELOG.md

@@ -9,6 +9,19 @@
   or any annotation.  It is not supported in the case when one of is used in
   conjunction with other constraints in the same schema object.
 
+### Bug Fixes
+
+- Supports using `$ref` in the root of a component, for example:
+
+    ```yaml
+    components:
+      schemas:
+        UserAlias:
+          $ref: '#/components/schemas/User'
+        User:
+          type: object
+    ```
+
 ## 0.13.1 (2020-06-22)
 
 ### Bug Fixes

packages/openapi3-parser/lib/parser/oas/parseComponentsObject.js

@@ -8,6 +8,7 @@ const {
   createInvalidMemberWarning,
 } = require('../annotations');
 const parseObject = require('../parseObject');
+const parseReference = require('../parseReference');
 const pipeParseResult = require('../../pipeParseResult');
 const parseSchemaObject = require('./parseSchemaObject');
 const parseParameterObject = require('./parseParameterObject');
@@ -71,6 +72,36 @@ const parseComponentMember = R.curry((context, parser, member) => {
   return parseResult;
 });
 
+function registerComponentStateInContext(context, components) {
+  const { namespace } = context;
+
+  // Component referencing supports recursive (and circular in some cases)
+  // references and thus we must know about all of the component IDs upfront.
+  // Below we are putting in the unparsed components so we can keep the
+  // dereferencing logic simple, these are used during parsing the components
+  // and later on the components in our context is replaced by the final parsed
+  // result.
+  // eslint-disable-next-line no-param-reassign
+  context.state.components = new namespace.elements.Object();
+
+  if (isObject(components)) {
+    components.forEach((value, key) => {
+      if (isObject(value)) {
+        // Take each component object (f.e schemas, parameters) and convert to
+        // object with members for each key (discarding value). We don't want the
+        // value making it into final parse results under any circumstance, for
+        // example if the parse errors out and we leave bad state
+
+        const componentObject = new namespace.elements.Object(
+          value.map((value, key) => new namespace.elements.Member(key))
+        );
+
+        context.state.components.set(key.toValue(), componentObject);
+      }
+    });
+  }
+}
+
 /**
  * Parse Components Object
  *
@@ -84,24 +115,7 @@ const parseComponentMember = R.curry((context, parser, member) => {
 function parseComponentsObject(context, element) {
   const { namespace } = context;
 
-  // Schema Object supports recursive (and circular) references and thus we
-  // must know about all of the schema IDs upfront. Below we are putting
-  // in the unparsed schemas so we can keep the dereferencing logic simple,
-  // these are used during parsing the schema components and later on the
-  // components in our context is replaced by the final parsed result.
-  // eslint-disable-next-line no-param-reassign
-  context.state.components = new namespace.elements.Object();
-
-  if (isObject(element) && element.get('schemas') && isObject(element.get('schemas'))) {
-    // Take schemas and convert to object with members for each key (discarding value)
-    // We don't want the value making it into final parse results under any circumstance,
-    // for example if the parse errors out and we leave bad state
-    const schemas = new namespace.elements.Object(
-      element.get('schemas').map((value, key) => new namespace.elements.Member(key))
-    );
-
-    context.state.components.set('schemas', schemas);
-  }
+  registerComponentStateInContext(context, element);
 
   const createMemberValueNotObjectWarning = member => createWarning(namespace,
     `'${name}' '${member.key.toValue()}' is not an object`, member.value);
@@ -117,24 +131,25 @@ function parseComponentsObject(context, element) {
    * @returns ParseResult<ObjectElement>
    * @private
    */
-  const parseComponentObjectMember = (parser) => {
+  const parseComponentObjectMember = R.curry((parser, member) => {
+    const component = member.key.toValue();
+
     const parseMember = parseComponentMember(context, parser);
+    const parseMemberOrRef = m => parseReference(component, () => parseMember(m), context, m.value, false, true);
 
-    return member => pipeParseResult(context.namespace,
+    return pipeParseResult(context.namespace,
       validateIsObject,
-      R.compose(parseObject(context, name, parseMember), getValue),
+      R.compose(parseObject(context, name, parseMemberOrRef), getValue),
       (object) => {
-        const contextMember = context.state.components.getMember(member.key.toValue());
+        const contextMember = context.state.components.getMember(component);
 
         if (contextMember) {
           contextMember.value = object;
-        } else {
-          context.state.components.push(new namespace.elements.Member(member.key, object));
         }
 
         return object;
       })(member);
-  };
+  });
 
   const setDataStructureId = (dataStructure, key) => {
     if (dataStructure) {

packages/openapi3-parser/lib/parser/oas/parseReferenceObject.js

@@ -12,6 +12,33 @@ const parseString = require('../parseString');
 const name = 'Reference Object';
 const requiredKeys = ['$ref'];
 
+/**
+ * Recursively dereference an element in the given component
+ *
+ * @param namespace {Namespace}
+ * @param component {ObjectElement}
+ * @param ref {StringElement}
+ * @param element {Element}
+ * @param parents {string[]} an optional collections of traversed parents
+ *
+ * @returns Element
+ */
+function dereference(namespace, component, ref, element, parents = []) {
+  if (parents && parents.includes(element.element)) {
+    // We've already cycled through this element. We're in a circular loop
+    parents.shift();
+    return createError(namespace, `Reference cannot be circular, '${ref.toValue()}' causes a circular reference via ${parents.join(', ')}`, ref);
+  }
+
+  const match = component.get(element.element);
+  if (match) {
+    parents.push(element.element);
+    return dereference(namespace, component, ref, match, parents);
+  }
+
+  return element;
+}
+
 /**
  * Parse Reference Object
  *
@@ -76,7 +103,7 @@ function parseReferenceObject(context, componentName, element, returnReferenceEl
     return new namespace.elements.ParseResult(
       component
         .filter((value, key) => key.toValue() === componentId && value)
-        .map(value => value)
+        .map(value => dereference(namespace, component, ref, value))
     );
   };
 

packages/openapi3-parser/lib/parser/parseReference.js

@@ -6,9 +6,9 @@ function isReferenceObject(element) {
   return isObject(element) && element.get('$ref') !== undefined;
 }
 
-function parseReference(component, parser, context, element, isInsideSchema) {
+function parseReference(component, parser, context, element, isInsideSchema, returnReferenceElement) {
   if (isReferenceObject(element)) {
-    const parseResult = parseReferenceObject(context, component, element, component === 'schemas');
+    const parseResult = parseReferenceObject(context, component, element, component === 'schemas' || returnReferenceElement);
 
     // If we're referencing a schema object and we're not inside a schema
     // parser (subschema), then we want to wrap the object in a data structure element

packages/openapi3-parser/test/integration/components-test.js

@@ -19,6 +19,11 @@ describe('components', () => {
       const file = path.join(fixtures, 'path-item-object-parameters-unsupported-parameter');
       return testParseFixture(file);
     });
+
+    it('handles parameter referencing with reference to alias', () => {
+      const file = path.join(fixtures, 'path-item-object-parameters-alias');
+      return testParseFixture(file);
+    });
   });
 
   describe('Media Type Object', () => {
@@ -72,9 +77,16 @@ describe('components', () => {
     });
   });
 
-  it("'Schema Object' circular references", () => {
-    const file = path.join(fixtures, 'schema-object-circular');
-    return testParseFixture(file);
+  describe('Schema Object', () => {
+    it('handles circular references', () => {
+      const file = path.join(fixtures, 'schema-object-circular');
+      return testParseFixture(file);
+    });
+
+    it('handles schema with reference to alias', () => {
+      const file = path.join(fixtures, 'schema-alias');
+      return testParseFixture(file);
+    });
   });
 
   it("'Operation Object' requestBody references", () => {

packages/openapi3-parser/test/integration/fixtures/components/path-item-object-parameters-alias.json

@@ -0,0 +1,54 @@
+{
+  "element": "parseResult",
+  "content": [
+    {
+      "element": "category",
+      "meta": {
+        "classes": {
+          "element": "array",
+          "content": [
+            {
+              "element": "string",
+              "content": "api"
+            }
+          ]
+        },
+        "title": {
+          "element": "string",
+          "content": "Parameter Component with alias"
+        }
+      },
+      "attributes": {
+        "version": {
+          "element": "string",
+          "content": "1.0.0"
+        }
+      },
+      "content": [
+        {
+          "element": "resource",
+          "attributes": {
+            "href": {
+              "element": "string",
+              "content": "/{?foo}"
+            },
+            "hrefVariables": {
+              "element": "hrefVariables",
+              "content": [
+                {
+                  "element": "member",
+                  "content": {
+                    "key": {
+                      "element": "string",
+                      "content": "foo"
+                    }
+                  }
+                }
+              ]
+            }
+          }
+        }
+      ]
+    }
+  ]
+}

packages/openapi3-parser/test/integration/fixtures/components/path-item-object-parameters-alias.yaml

@@ -0,0 +1,15 @@
+openapi: "3.0.0"
+info:
+  version: 1.0.0
+  title: Parameter Component with alias
+paths:
+  /:
+    parameters:
+      - $ref: '#/components/parameters/UserAlias'
+components:
+  parameters:
+    User:
+      in: query
+      name: foo
+    UserAlias:
+      $ref: '#/components/parameters/User'