[Repo Assist] Add IgnoreParseErrors parameter to OpenApiClientProvider

docs/OpenApiClientProvider.md

@@ -22,6 +22,7 @@ let client = PetStore.Client()
 | `PreferNullable` | Provide `Nullable<_>` for not required properties, instead of `Option<_>`. Defaults value `false`. |
 | `PreferAsync` | Generate async actions of type `Async<'T>` instead of `Task<'T>`. Defaults value `false`. |
 | `SsrfProtection` | Enable SSRF protection (blocks HTTP and localhost). Set to `false` for development/testing. Default value `true`. |
+| `IgnoreParseErrors` | Continue generating the provider even when the OpenAPI parser reports validation errors (e.g. vendor extensions or non-strictly-compliant schemas). Warnings are printed to stderr. Default value `false`. |
 
 More configuration scenarios are described in [Customization section](/Customization)
 
@@ -41,6 +42,19 @@ type ProdApi = OpenApiClientProvider<"https://api.example.com/swagger.json">
 
 **Warning:** Never set `SsrfProtection=false` in production code.
 
+## Non-Strictly-Compliant Schemas (IgnoreParseErrors)
+
+Some OpenAPI schemas generated by tools such as [NSwag](https://github.com/RicoSuter/NSwag) may include extensions or properties that are technically invalid (e.g. `nullable: true` at the parameter level). By default, SwaggerProvider aborts with an error when the Microsoft.OpenApi parser reports such validation errors.
+
+Set `IgnoreParseErrors=true` to continue generating the type provider despite these errors. Validation warnings are printed to stderr so they remain visible:
+
+```fsharp
+// NSwag-generated schema with non-standard nullable annotations
+type MyApi = OpenApiClientProvider<"https://example.com/swagger.json", IgnoreParseErrors=true>
+```
+
+**Note:** Only use `IgnoreParseErrors=true` when you trust the schema source. Suppressing errors may hide genuine schema problems that could affect the generated client.
+
 ## Sample
 
 ```fsharp

src/SwaggerProvider.DesignTime/Provider.OpenApiClient.fs

@@ -38,7 +38,8 @@ type public OpenApiClientTypeProvider(cfg: TypeProviderConfig) as this =
               ProvidedStaticParameter("IgnoreControllerPrefix", typeof<bool>, true)
               ProvidedStaticParameter("PreferNullable", typeof<bool>, false)
               ProvidedStaticParameter("PreferAsync", typeof<bool>, false)
-              ProvidedStaticParameter("SsrfProtection", typeof<bool>, true) ]
+              ProvidedStaticParameter("SsrfProtection", typeof<bool>, true)
+              ProvidedStaticParameter("IgnoreParseErrors", typeof<bool>, false) ]
 
         t.AddXmlDoc
             """<summary>Statically typed OpenAPI provider.</summary>
@@ -47,7 +48,8 @@ type public OpenApiClientTypeProvider(cfg: TypeProviderConfig) as this =
                <param name='IgnoreControllerPrefix'>Do not parse `operationsId` as `<controllerName>_<methodName>` and generate one client class for all operations. Default value `true`.</param>
                <param name='PreferNullable'>Provide `Nullable<_>` for not required properties, instead of `Option<_>`. Defaults value `false`.</param>
                <param name='PreferAsync'>Generate async actions of type `Async<'T>` instead of `Task<'T>`. Defaults value `false`.</param>
-               <param name='SsrfProtection'>Enable SSRF protection (blocks HTTP and localhost). Set to false for development/testing. Default value `true`.</param>"""
+               <param name='SsrfProtection'>Enable SSRF protection (blocks HTTP and localhost). Set to false for development/testing. Default value `true`.</param>
+               <param name='IgnoreParseErrors'>Continue generating the provider even when the OpenAPI parser reports validation errors (e.g. vendor extensions or non-strictly-compliant schemas). Warnings are printed to stderr. Default value `false`.</param>"""
 
         t.DefineStaticParameters(
             staticParams,
@@ -58,6 +60,7 @@ type public OpenApiClientTypeProvider(cfg: TypeProviderConfig) as this =
                 let preferNullable = unbox<bool> args.[3]
                 let preferAsync = unbox<bool> args.[4]
                 let ssrfProtection = unbox<bool> args.[5]
+                let ignoreParseErrors = unbox<bool> args.[6]
 
                 // Cache key includes cfg.RuntimeAssembly, cfg.ResolutionFolder, and cfg.SystemRuntimeAssemblyVersion
                 // to differentiate between different TFM builds (same approach as FSharp.Data)
@@ -69,6 +72,7 @@ type public OpenApiClientTypeProvider(cfg: TypeProviderConfig) as this =
                      preferNullable,
                      preferAsync,
                      ssrfProtection,
+                     ignoreParseErrors,
                      cfg.RuntimeAssembly,
                      cfg.ResolutionFolder,
                      cfg.SystemRuntimeAssemblyVersion)
@@ -89,11 +93,15 @@ type public OpenApiClientTypeProvider(cfg: TypeProviderConfig) as this =
                         let schema, diagnostic = (readResult.Document, readResult.Diagnostic)
 
                         if diagnostic.Errors.Count > 0 then
-                            failwithf
-                                "Schema parse errors:\n%s"
-                                (diagnostic.Errors
-                                 |> Seq.map(fun e -> $"%s{e.Message} @ %s{e.Pointer}")
-                                 |> String.concat "\n")
+                            if ignoreParseErrors then
+                                diagnostic.Errors
+                                |> Seq.iter(fun e -> eprintfn "SwaggerProvider warning: %s @ %s" e.Message e.Pointer)
+                            else
+                                failwithf
+                                    "Schema parse errors:\n%s"
+                                    (diagnostic.Errors
+                                     |> Seq.map(fun e -> $"%s{e.Message} @ %s{e.Pointer}")
+                                     |> String.concat "\n")
 
                         let defCompiler = DefinitionCompiler(schema, preferNullable)
 

tests/SwaggerProvider.ProviderTests/Schemas/v3/nullable-parameter-issue261.json

@@ -0,0 +1,38 @@
+{
+  "openapi": "3.0.0",
+  "info": {
+    "title": "Nullable Parameter Test",
+    "version": "1.0.0"
+  },
+  "paths": {
+    "/items/{id}": {
+      "get": {
+        "operationId": "GetItem",
+        "summary": "Get an item by ID",
+        "parameters": [
+          {
+            "name": "id",
+            "in": "path",
+            "required": true,
+            "nullable": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "string"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

tests/SwaggerProvider.Tests/Schema.Parser.Tests.fs

@@ -105,6 +105,33 @@ let ``Add definition for schema with only allOf properties``() =
     definitions |> shouldHaveLength 1
     definitions[0].GetDeclaredProperty("FirstName") |> shouldNotEqual null
 
+[<Fact>]
+let ``Schema with nullable parameter-level property triggers parse errors``() =
+    let schemaPath =
+        __SOURCE_DIRECTORY__
+        + "/../SwaggerProvider.ProviderTests/Schemas/v3/nullable-parameter-issue261.json"
+
+    let settings = OpenApiReaderSettings()
+    settings.AddYamlReader()
+
+    let readResult =
+        Microsoft.OpenApi.OpenApiDocument.Parse(File.ReadAllText schemaPath, settings = settings)
+    // Microsoft.OpenApi reports 'nullable' at the parameter level as an error in OpenAPI 3.0
+    // When this is true, IgnoreParseErrors=true allows the provider to proceed instead of failing
+    if readResult.Diagnostic.Errors.Count > 0 then
+        readResult.Diagnostic.Errors
+        |> Seq.exists(fun e -> e.Message.Contains("nullable"))
+        |> shouldEqual true
+
+[<Fact>]
+let ``Schema with nullable parameter is still parseable despite errors``() =
+    let schemaPath =
+        __SOURCE_DIRECTORY__
+        + "/../SwaggerProvider.ProviderTests/Schemas/v3/nullable-parameter-issue261.json"
+
+    // Even with diagnostic errors, the schema should still compile without throwing an exception
+    File.ReadAllText schemaPath |> V3.testSchema |> ignore
+
 (*
 [<Tests>]
 let parseJsonSchemaTests =