Use string type for parameters with no schemas. (#3392)

* Use string type for parameters with no schemas.

* Add test for schema-less parameter.
Add changelog entry.

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Removed redundant undefined qualifier in TypeScript for properties. [#3244](https://github.com/microsoft/kiota/issues/3244)
 - The default status code response is now used as 4XX and 5XX when those class responses are not provided in the description. [#3245](https://github.com/microsoft/kiota/issues/3245)
 - Adds codes files in typescript to reduce number of generated files. [#2116](https://github.com/microsoft/kiota/issues/2116)
+- Fix null reference exception when a parameter is defined without a schema. (CLI).
 
 ## [1.6.1] - 2023-09-11
 

src/Kiota.Builder/KiotaBuilder.cs

@@ -1442,7 +1442,7 @@ private void CreateOperationMethods(OpenApiUrlTreeNode currentNode, OperationTyp
         {
             Name = codeName,
             SerializationName = codeName.Equals(x.Name, StringComparison.Ordinal) ? string.Empty : x.Name,
-            Type = GetQueryParameterType(x.Schema),
+            Type = x.Schema is null ? GetDefaultQueryParameterType() : GetQueryParameterType(x.Schema),
             Documentation = new()
             {
                 Description = x.Description.CleanupDescription(),
@@ -2321,6 +2321,15 @@ private void AddPropertyForQueryParameter(OpenApiParameter parameter, CodeClass
             logger.LogWarning("Ignoring duplicate parameter {Name}", parameter.Name);
         }
     }
+
+    private static CodeType GetDefaultQueryParameterType()
+    {
+        return new()
+        {
+            IsExternal = true,
+            Name = "string",
+        };
+    }
     private static CodeType GetQueryParameterType(OpenApiSchema schema) =>
         new()
         {

tests/Kiota.Builder.Tests/KiotaBuilderTests.cs

@@ -783,6 +783,30 @@ public async Task DoesntFailOnEmptyKiotaExtension()
         Assert.Null(extensionResult);
     }
     [Fact]
+    public async Task DoesntFailOnParameterWithoutSchemaKiotaExtension()
+    {
+        var tempFilePath = Path.Combine(Path.GetTempPath(), Path.GetTempFileName());
+        await using var fs = await GetDocumentStream(@"openapi: 3.0.1
+info:
+  title: OData Service for namespace microsoft.graph
+  description: This OData service is located at https://graph.microsoft.com/v1.0
+  version: 1.0.1
+servers:
+  - url: https://graph.microsoft.com/v1.0
+paths:
+  '/users/{user-id}':
+    get:
+      parameters:
+      - name: user-id
+        in: path");
+        var mockLogger = new Mock<ILogger<KiotaBuilder>>();
+        var builder = new KiotaBuilder(mockLogger.Object, new GenerationConfiguration { ClientClassName = "Graph", OpenAPIFilePath = tempFilePath, Language = GenerationLanguage.CLI }, _httpClient);
+        var document = await builder.CreateOpenApiDocumentAsync(fs);
+        var node = builder.CreateUriSpace(document);
+        var model = builder.CreateSourceModel(node);
+        Assert.NotNull(model);
+    }
+    [Fact]
     public async Task GetsUrlTreeNode()
     {
         var tempFilePath = Path.Combine(Path.GetTempPath(), Path.GetTempFileName());