✨ __typename support

Author: aexol

package.json

@@ -1,6 +1,6 @@
 {
   "name": "graphql-js-tree",
-  "version": "0.3.3",
+  "version": "0.3.4",
   "private": false,
   "license": "MIT",
   "description": "GraphQL Parser providing simplier structure",

src/GqlParser/index.ts

@@ -3,7 +3,7 @@ import { OperationType, ParserField, TypeDefinition } from '@/Models';
 import { GqlParserTree, VariableDefinitionWithoutLoc } from '@/Models/GqlParserTree';
 import { Parser } from '@/Parser';
 import { TypeResolver } from '@/Parser/typeResolver';
-import { compileType, getTypeName } from '@/shared';
+import { compileType, createPlainField, getTypeName } from '@/shared';
 import {
   DefinitionNode,
   parse,
@@ -123,7 +123,13 @@ export const parseGql = (gql: string, schema: string) => {
   };
 
   const composeFieldNode = (s: FieldNode, parentNode: ParserField): GqlParserTree => {
-    const fieldNode = parentNode.args.find((a) => a.name === s.name.value);
+    const fieldNode =
+      s.name.value === '__typename'
+        ? createPlainField({
+            name: '__typename',
+            type: 'String!',
+          })
+        : parentNode.args.find((a) => a.name === s.name.value);
     if (!fieldNode) {
       throw new Error(`Field "${s.name.value}" does not exist in "${parentNode.name}" node`);
     }

src/__tests__/GqlParser/GqlParserTreeToGql.spec.ts

@@ -224,6 +224,38 @@ describe('Test generation of gql strings from the GqlParserTree', () => {
     const gqlParserResultVars = enrichGqlQueryWithAllVars(mockStartingQuery, mockSchema);
     expectTrimmedEqual(gqlParserResultVars, mockQueryVars);
   });
+
+  it('Works with __typename', () => {
+    const mockQueryFragment = `
+    query MyQuery {
+      user{
+        __typename
+      }
+    }`;
+    const GqlTreeMockWithFragments: GqlParserTree[] = [
+      {
+        name: 'MyQuery',
+        node: queryNode,
+        operation: OperationType.query,
+        children: [
+          {
+            name: 'user',
+            node: queryNode.args[1],
+            children: [
+              {
+                name: '__typename',
+                node: createPlainField({ name: '__typename', type: 'String!' }),
+              },
+            ],
+          },
+        ],
+      },
+    ];
+
+    const gqlParserResult = parseGqlTrees(GqlTreeMockWithFragments);
+    expectTrimmedEqual(gqlParserResult, mockQueryFragment);
+  });
+
   it('Works with fragments and fragment spreads', () => {
     const mockQueryFragment = `
     fragment Full on User{
@@ -292,6 +324,7 @@ describe('Test generation of gql strings from the GqlParserTree', () => {
     const gqlParserResult = parseGqlTrees(GqlTreeMockWithFragments);
     expectTrimmedEqual(gqlParserResult, mockQueryFragment);
   });
+
   it('works with inline fragments', () => {
     const mockQueryInline = `query MyQuery {
       namings{

src/__tests__/GqlParser/index.spec.ts

@@ -194,6 +194,37 @@ describe('Test generation of GqlParserTrees from gql', () => {
     const gqlParserResult = parseGql(mockQueryVars, mockSchema);
     expect(gqlParserResult[0]).toEqual(GqlTreeMockWithVars);
   });
+  it('Creates __typename node', () => {
+    const mockQueryFragment = `
+    query MyQuery {
+      user{
+        __typename
+      }
+    }`;
+    const GqlTreeMockWithFragments: GqlParserTree[] = [
+      {
+        name: 'MyQuery',
+        node: queryNode,
+        operation: OperationType.query,
+        children: [
+          {
+            name: 'user',
+            node: queryNode.args[1],
+            children: [
+              {
+                name: '__typename',
+                node: createPlainField({ name: '__typename', type: 'String!' }),
+              },
+            ],
+          },
+        ],
+      },
+    ];
+
+    const gqlParserResult = parseGql(mockQueryFragment, mockSchema);
+    expect(gqlParserResult[0]).toEqual(GqlTreeMockWithFragments[0]);
+  });
+
   it('Creates gql with fragment and fragment spread', () => {
     const mockQueryFragment = `
     fragment Full on User{
@@ -263,6 +294,7 @@ describe('Test generation of GqlParserTrees from gql', () => {
     expect(gqlParserResult[0]).toEqual(GqlTreeMockWithFragments[0]);
     expect(gqlParserResult[1]).toEqual(GqlTreeMockWithFragments[1]);
   });
+
   it('Parses inline fragments from gql on unions', () => {
     const mockQueryInline = `query MyQuery {
       namings{