GQL-48: Finalized feature

- Added examples in README.md
- Added support for embedding inline fragments in query builder selection set

Author: mghoneimy

Changelog.md

@@ -5,13 +5,14 @@ between each release.
 
 ## Tech Debt
 
-- Refactor the query conversion to string to separate the process of constructing a query and adding a field
+- Refactor the query conversion to string to separate the process of
+constructing a new query and adding a nested subfield
 
 ## 1.3: 2019-08-03
 
 ### Added
 
-- Support for inline fragments in the package
+- Support for inline fragments
 
 ## 1.2: 2019-07-24
 

README.md

@@ -178,6 +178,30 @@ false by default
 variable. The default value will only be considered
 if the isRequired argument is set to false.
 
+## Using Interfaces: Query With Inline Fragments
+
+When querying a field that returns an interface type, you might need to use
+inline fragments to access data on the underlying concrete type.
+
+This example show how to generate inline fragments using this package:
+
+```
+$gql = new Query('companies');
+$gql->setSelectionSet(
+    [
+        'serialNumber',
+        'name',
+        (new InlineFragment('PrivateCompany'))
+            ->setSelectionSet(
+                [
+                    'boardMembers',
+                    'shareholders',
+                ]
+            ),
+    ]
+);
+```
+
 # The Query Builder
 
 The QueryBuilder class can be used to construct Query objects dynamically, which

src/QueryBuilder/AbstractQueryBuilder.php

@@ -3,6 +3,7 @@
 namespace GraphQL\QueryBuilder;
 
 use GraphQL\Exception\EmptySelectionSetException;
+use GraphQL\InlineFragment;
 use GraphQL\Query;
 use GraphQL\RawObject;
 use GraphQL\Variable;
@@ -77,7 +78,12 @@ public function getQuery(): Query
      */
     protected function selectField($selectedField)
     {
-        if (is_string($selectedField) || $selectedField instanceof AbstractQueryBuilder || $selectedField instanceof Query) {
+        if (
+            is_string($selectedField)
+            || $selectedField instanceof AbstractQueryBuilder
+            || $selectedField instanceof Query
+            || $selectedField instanceof InlineFragment
+        ) {
             $this->selectionSet[] = $selectedField;
         }
 

tests/QueryBuilderTest.php

@@ -3,6 +3,7 @@
 namespace GraphQL\Tests;
 
 use GraphQL\Exception\EmptySelectionSetException;
+use GraphQL\InlineFragment;
 use GraphQL\Query;
 use GraphQL\QueryBuilder\QueryBuilder;
 use GraphQL\RawObject;
@@ -171,6 +172,28 @@ public function testSelectNestedQueryBuilder()
         );
     }
 
+    /**
+     * @covers \GraphQL\QueryBuilder\QueryBuilder::getQuery
+     * @covers \GraphQL\QueryBuilder\QueryBuilder::selectField
+     */
+    public function testSelectInlineFragment()
+    {
+        $this->queryBuilder->selectField(
+            (new InlineFragment('Type'))
+                ->setSelectionSet(['field'])
+        );
+        $this->assertEquals(
+            'query {
+Object {
+... on Type {
+field
+}
+}
+}',
+            (string) $this->queryBuilder->getQuery()
+        );
+    }
+
     /**
      * @covers \GraphQL\QueryBuilder\QueryBuilder::getQuery
      * @covers \GraphQL\QueryBuilder\QueryBuilder::setArgument