feat: instance contextual layout fetching

src/Altinn.App.Api/Controllers/ResourceController.cs

@@ -1,3 +1,4 @@
+using Altinn.App.Core.Features;
 using Altinn.App.Core.Helpers;
 using Altinn.App.Core.Internal.App;
 using Microsoft.AspNetCore.Mvc;
@@ -11,14 +12,17 @@ namespace Altinn.App.Api.Controllers;
 public class ResourceController : ControllerBase
 {
     private readonly IAppResources _appResourceService;
+    private readonly AppImplementationFactory _appImplementationFactory;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="ResourceController"/> class
     /// </summary>
     /// <param name="appResourcesService">The execution service</param>
-    public ResourceController(IAppResources appResourcesService)
+    /// <param name="serviceProvider">The service provider</param>
+    public ResourceController(IAppResources appResourcesService, IServiceProvider serviceProvider)
     {
         _appResourceService = appResourcesService;
+        _appImplementationFactory = serviceProvider.GetRequiredService<AppImplementationFactory>();
     }
 
     /// <summary>
@@ -71,6 +75,44 @@ public ActionResult GetLayouts(string org, string app, string id)
         return Ok(layouts);
     }
 
+    /// <summary>
+    /// Endpoint for layouts with instance context.
+    /// Uses ICustomLayoutForInstance if implemented with IAppResources as fallback.
+    /// </summary>
+    /// <param name="org">The application owner short name</param>
+    /// <param name="app">The application name</param>
+    /// <param name="instanceOwnerPartyId">The instance owner party id</param>
+    /// <param name="instanceId">The instance id</param>
+    /// <param name="layoutSetId">The layout set id</param>
+    /// <returns>A collection of FormLayout objects in JSON format.</returns>
+    [ProducesResponseType(typeof(string), StatusCodes.Status200OK, "application/json")]
+    [HttpGet]
+    [Route("{org}/{app}/instances/{instanceOwnerPartyId:int}/{instanceId}/layouts/{layoutSetId}")]
+    public async Task<ActionResult> GetInstanceLayouts(
+        string org,
+        string app,
+        int instanceOwnerPartyId,
+        string instanceId,
+        string layoutSetId
+    )
+    {
+        ICustomLayoutForInstance? customLayoutService = _appImplementationFactory.Get<ICustomLayoutForInstance>();
+        if (customLayoutService is not null)
+        {
+            string? customLayout = await customLayoutService.GetCustomLayoutForInstance(
+                layoutSetId,
+                instanceOwnerPartyId,
+                Guid.Parse(instanceId)
+            );
+            if (customLayout is not null)
+            {
+                return Ok(customLayout);
+            }
+        }
+        string layouts = _appResourceService.GetLayoutsForSet(layoutSetId);
+        return Ok(layouts);
+    }
+
     /// <summary>
     /// Get the layout settings.
     /// </summary>
@@ -86,6 +128,44 @@ public ActionResult GetLayoutSettings(string org, string app)
         return Ok(settings);
     }
 
+    /// <summary>
+    /// Endpoint for layout settings with instance context.
+    /// Uses ICustomLayoutForInstance if implemented with IAppResources as fallback.
+    /// </summary>
+    /// <param name="org">The application owner short name</param>
+    /// <param name="app">The application name</param>
+    /// <param name="instanceOwnerPartyId">The instance owner party id</param>
+    /// <param name="instanceId">The instance id</param>
+    /// <param name="layoutSetId">The layout set id</param>
+    /// <returns>The settings in the form of a string.</returns>
+    [ProducesResponseType(typeof(string), StatusCodes.Status200OK, "application/json")]
+    [HttpGet]
+    [Route("{org}/{app}/instances/{instanceOwnerPartyId:int}/{instanceId}/layoutsettings/{layoutSetId}")]
+    public async Task<ActionResult> GetInstanceLayoutSettings(
+        string org,
+        string app,
+        int instanceOwnerPartyId,
+        string instanceId,
+        string layoutSetId
+    )
+    {
+        ICustomLayoutForInstance? customLayoutService = _appImplementationFactory.Get<ICustomLayoutForInstance>();
+        if (customLayoutService is not null)
+        {
+            string? customLayoutSettings = await customLayoutService.GetCustomLayoutSettingsForInstance(
+                layoutSetId,
+                instanceOwnerPartyId,
+                Guid.Parse(instanceId)
+            );
+            if (customLayoutSettings is not null)
+            {
+                return Ok(customLayoutSettings);
+            }
+        }
+        string? settings = _appResourceService.GetLayoutSettingsStringForSet(layoutSetId);
+        return Ok(settings);
+    }
+
     /// <summary>
     /// Get the layout settings.
     /// </summary>

src/Altinn.App.Core/Features/FeatureFlags.cs

@@ -12,4 +12,11 @@ public static class FeatureFlags
     /// return validation errors in the response body instead of a string.
     /// </summary>
     public const string JsonObjectInDataResponse = "JsonObjectInDataResponse";
+
+    // TODO: write a better summary here
+    /// <summary>
+    /// Enabling this feature changes backend endpoint used for layouts to
+    /// add instance identifier.
+    /// </summary>
+    public const string AddInstanceIdentifierToLayoutRequests = "AddInstanceIdentifierToLayoutRequests";
 }

src/Altinn.App.Core/Internal/App/FrontendFeatures.cs

@@ -26,6 +26,15 @@ public FrontendFeatures(IFeatureManager featureManager)
         {
             _features.Add("jsonObjectInDataResponse", false);
         }
+
+        if (featureManager.IsEnabledAsync(FeatureFlags.AddInstanceIdentifierToLayoutRequests).Result)
+        {
+            _features.Add("addInstanceIdentifierToLayoutRequests", true);
+        }
+        else
+        {
+            _features.Add("addInstanceIdentifierToLayoutRequests", false);
+        }
     }
 
     /// <inheritdoc />

src/Altinn.App.Core/Internal/App/ICustomLayoutForInstance.cs

@@ -0,0 +1,26 @@
+using Altinn.App.Core.Features;
+
+namespace Altinn.App.Core.Internal.App;
+
+/// <summary>
+/// Interface for getting custom layouts for an instance.
+/// </summary>
+[ImplementableByApps]
+public interface ICustomLayoutForInstance
+{
+    /// <summary>
+    /// Gets the custom layout
+    /// </summary>
+    /// <param name="layoutSetId">The layout set ID</param>
+    /// <param name="instanceOwnerPartyId">The instance owner party ID</param>
+    /// <param name="instanceGuid">The instance GUID</param>
+    Task<string?> GetCustomLayoutForInstance(string layoutSetId, int instanceOwnerPartyId, Guid instanceGuid);
+
+    /// <summary>
+    /// Gets the custom layout settings
+    /// </summary>
+    /// <param name="layoutSetId">The layout set ID</param>
+    /// <param name="instanceOwnerPartyId">The instance owner party ID</param>
+    /// <param name="instanceGuid">The instance GUID</param>
+    Task<string?> GetCustomLayoutSettingsForInstance(string layoutSetId, int instanceOwnerPartyId, Guid instanceGuid);
+}

src/Altinn.App.Core/Models/DataElementIdentifier.cs

@@ -55,7 +55,8 @@ public DataElementIdentifier(DataElement dataElement)
     /// <summary>
     /// Implicit conversion to allow DataElements to be used as DataElementIds
     /// </summary>
-    public static implicit operator DataElementIdentifier(DataElement dataElement) => new(dataElement);
+    public static implicit operator DataElementIdentifier(DataElement dataElement) =>
+        dataElement is null ? throw new ArgumentNullException(nameof(dataElement)) : new(dataElement);
 
     /// <summary>
     /// Implicit conversion to allow DataElements to be used as DataElementIds,

test/Altinn.App.Api.Tests/Controllers/ResourceController_CustomLayoutTests.cs

@@ -0,0 +1,131 @@
+using System.Net;
+using System.Text.Json;
+using Altinn.App.Api.Tests.Data;
+using Altinn.App.Core.Internal.App;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit.Abstractions;
+
+namespace Altinn.App.Api.Tests.Controllers;
+
+public class ResourceController_CustomLayoutTests : ApiTestBase, IClassFixture<WebApplicationFactory<Program>>
+{
+    public ResourceController_CustomLayoutTests(WebApplicationFactory<Program> factory, ITestOutputHelper outputHelper)
+        : base(factory, outputHelper) { }
+
+    private class CustomLayoutForInstance : ICustomLayoutForInstance
+    {
+        public Task<string?> GetCustomLayoutForInstance(string layoutSetId, int instanceOwnerPartyId, Guid instanceId)
+        {
+            return Task.FromResult<string?>(instanceId.ToString());
+        }
+
+        public Task<string?> GetCustomLayoutSettingsForInstance(
+            string layoutSetId,
+            int instanceOwnerPartyId,
+            Guid instanceId
+        )
+        {
+            return Task.FromResult<string?>(instanceId.ToString());
+        }
+    }
+
+    [Fact]
+    public async Task GetLayoutsForSet_WithCustomLayoutForInstanceService_ReturnsOk()
+    {
+        OverrideServicesForThisTest = (services) =>
+        {
+            services.AddSingleton<ICustomLayoutForInstance, CustomLayoutForInstance>();
+        };
+
+        string org = "tdd";
+        string app = "contributer-restriction";
+        int instanceOwnerPartyId = 500600;
+        Guid instanceGuid = Guid.Parse("cff1cb24-5bc1-4888-8e06-c634753c5144");
+        string layoutSetId = "default";
+        using HttpClient client = GetRootedUserClient(org, app, 1337, instanceOwnerPartyId);
+
+        TestData.PrepareInstance(org, app, instanceOwnerPartyId, instanceGuid);
+        var response = await client.GetAsync(
+            $"/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/layouts/{layoutSetId}"
+        );
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var content = await response.Content.ReadAsStringAsync();
+        Assert.Equal(instanceGuid.ToString(), content);
+    }
+
+    [Fact]
+    public async Task GetLayoutsForSet_WithoutCustomLayoutForInstanceService_ReturnsOk()
+    {
+        string org = "tdd";
+        string app = "contributer-restriction";
+        int instanceOwnerPartyId = 500600;
+        Guid instanceGuid = Guid.Parse("cff1cb24-5bc1-4888-8e06-c634753c5144");
+        string layoutSetId = "default";
+        using HttpClient client = GetRootedUserClient(org, app, 1337, instanceOwnerPartyId);
+
+        TestData.PrepareInstance(org, app, instanceOwnerPartyId, instanceGuid);
+        var response = await client.GetAsync(
+            $"/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/layouts/{layoutSetId}"
+        );
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var content = await response.Content.ReadAsStringAsync();
+        using var jsonDoc = JsonDocument.Parse(content);
+        var root = jsonDoc.RootElement;
+        Assert.Equal(JsonValueKind.Object, root.ValueKind);
+        Assert.True(root.TryGetProperty("page", out var pageLayout));
+        Assert.True(pageLayout.TryGetProperty("data", out var data));
+        Assert.True(data.TryGetProperty("layout", out var layout));
+        Assert.Equal(JsonValueKind.Array, layout.ValueKind);
+        Assert.True(layout.GetArrayLength() > 0);
+    }
+
+    [Fact]
+    public async Task GetLayoutSettingsForSet_WithCustomLayoutForInstanceService_ReturnsOk()
+    {
+        OverrideServicesForThisTest = (services) =>
+        {
+            services.AddSingleton<ICustomLayoutForInstance, CustomLayoutForInstance>();
+        };
+
+        string org = "tdd";
+        string app = "contributer-restriction";
+        int instanceOwnerPartyId = 500600;
+        Guid instanceGuid = Guid.Parse("cff1cb24-5bc1-4888-8e06-c634753c5144");
+        string layoutSetId = "default";
+        using HttpClient client = GetRootedUserClient(org, app, 1337, instanceOwnerPartyId);
+
+        TestData.PrepareInstance(org, app, instanceOwnerPartyId, instanceGuid);
+        var response = await client.GetAsync(
+            $"/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/layoutsettings/{layoutSetId}"
+        );
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var content = await response.Content.ReadAsStringAsync();
+        Assert.Equal(instanceGuid.ToString(), content);
+    }
+
+    [Fact]
+    public async Task GetLayoutSettingsForSet_WithoutCustomLayoutForInstanceService_ReturnsOk()
+    {
+        string org = "tdd";
+        string app = "contributer-restriction";
+        int instanceOwnerPartyId = 500600;
+        Guid instanceGuid = Guid.Parse("cff1cb24-5bc1-4888-8e06-c634753c5144");
+        string layoutSetId = "default";
+        using HttpClient client = GetRootedUserClient(org, app, 1337, instanceOwnerPartyId);
+
+        TestData.PrepareInstance(org, app, instanceOwnerPartyId, instanceGuid);
+        var response = await client.GetAsync(
+            $"/{org}/{app}/instances/{instanceOwnerPartyId}/{instanceGuid}/layoutsettings/{layoutSetId}"
+        );
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var content = await response.Content.ReadAsStringAsync();
+        using var jsonDoc = JsonDocument.Parse(content);
+        var root = jsonDoc.RootElement;
+        Assert.Equal(JsonValueKind.Object, root.ValueKind);
+    }
+}