Make component expressions subform aware (#1698)

Previously you could not use "component" expressions in subforms, because the context lookup did error because multiple contexts would match.

Author: ivarne

src/Altinn.App.Core/Internal/Expressions/ExpressionEvaluator.cs

@@ -260,7 +260,7 @@ LayoutEvaluatorState state
             throw new ArgumentException("The component expression requires a component context");
         }
 
-        var targetContext = await state.GetComponentContext(context.Component?.PageId, componentId, context.RowIndices);
+        var targetContext = await state.GetComponentContext(componentId, relativeContext: context);
 
         if (targetContext is null)
         {

src/Altinn.App.Core/Internal/Expressions/LayoutEvaluatorState.cs

@@ -113,9 +113,50 @@ public void GetComponent(string pageName, string componentId)
         throw new NotSupportedException("GetComponent is not supported, use GetComponentContext instead.");
     }
 
+    /// <summary>
+    /// Get a specific component context from the state relative to another contexts subform data element and row indexes.
+    /// </summary>
+    public async Task<ComponentContext?> GetComponentContext(string componentId, ComponentContext relativeContext)
+    {
+        if (_componentModel is null)
+        {
+            throw new InvalidOperationException("Component model not loaded");
+        }
+
+        var contexts = (await GetComponentContexts()).SelectMany(c => c.Descendants);
+
+        if (relativeContext.DataElementIdentifier is not null)
+        {
+            // Filter out contexts that does not have the same data element identifier as the relative context, this ensures that we only get contexts from the same subform repeat group when there are multiple in the same layout
+            contexts = contexts.Where(c => c.DataElementIdentifier == relativeContext.DataElementIdentifier);
+        }
+        // Filter out all contexts that have the wrong Id
+        // Filter out contexts that does not have a prefix matching
+        var filteredContexts = contexts
+            .Where(c => c.Component?.Id == componentId)
+            .Where(c => RowIndexMatch(relativeContext.RowIndices, c.RowIndices))
+            .ToArray();
+        if (filteredContexts.Length == 0)
+        {
+            return null; // No context found
+        }
+
+        if (filteredContexts.Length == 1)
+        {
+            return filteredContexts[0];
+        }
+
+        throw new InvalidOperationException(
+            $"Multiple contexts found for {componentId} with [{(relativeContext.RowIndices is null ? "" : string.Join(", ", relativeContext.RowIndices))}]"
+        );
+    }
+
     /// <summary>
     /// Get a specific component context from the state
     /// </summary>
+    [Obsolete(
+        "A context is not uniquely identified by componentId and rowIndexes, use GetComponentContext(string, ComponentContext) instead so that we get subform data element as well."
+    )]
     public async Task<ComponentContext?> GetComponentContext(
         string? pageName,
         string componentId,

test/Altinn.App.Core.Tests/LayoutExpressions/CommonTests/ExpressionTestCaseRoot.cs

@@ -3,6 +3,7 @@
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Internal.Expressions;
 using Altinn.App.Core.Models.Expressions;
+using Altinn.App.Core.Models.Layout;
 using Altinn.App.Core.Models.Layout.Components;
 using Altinn.Platform.Storage.Interface.Models;
 
@@ -106,11 +107,7 @@ public async Task<ComponentContext> GetContextOrNull(LayoutEvaluatorState state)
         if (Context is not null)
         {
             //! Some tests do not need context, but it is not nullable in expression evaluator
-            context = await state.GetComponentContext(
-                Context.CurrentPageName,
-                Context.ComponentId,
-                Context.RowIndices
-            )!;
+            context = await state.GetComponentContext(Context.ComponentId, Context.ToContext())!;
         }
 
         //! Some tests do not need context, but it is not nullable in expression evaluator
@@ -167,4 +164,24 @@ public static ComponentContextForTestSpec FromContext(ComponentContext context)
             RowIndices = context.RowIndices,
         };
     }
+
+    public ComponentContext ToContext() =>
+        new ComponentContext(
+            null!,
+            new UnknownComponent
+            {
+                Id = ComponentId,
+                PageId = CurrentPageName,
+                LayoutId = "layout",
+                Type = "unknown",
+                Hidden = default,
+                RemoveWhenHidden = default,
+                Required = default,
+                ReadOnly = default,
+                DataModelBindings = new Dictionary<string, ModelBinding>(),
+                TextResourceBindings = new Dictionary<string, Expression>(),
+            },
+            RowIndices ?? Array.Empty<int>(),
+            null
+        );
 }

test/Altinn.App.Core.Tests/LayoutExpressions/FullTests/SubForm/SubFormTests.cs

@@ -178,7 +178,7 @@ private record SubFormModel(
                       "dataModelBindings": {
                         "simpleBinding": "Address"
                       },
-                      "required": true
+                      "required": ["notEquals", ["component", "Name"], "Always required, by test component lookup"]
                     },
                     {
                       "id": "Phone",

test/Altinn.App.Core.Tests/PublicApiTests.PublicApi_ShouldNotChange_Unintentionally.verified.txt

@@ -3254,6 +3254,10 @@ namespace Altinn.App.Core.Internal.Expressions
         public int CountDataElements(string dataTypeId) { }
         [System.Obsolete("You need to get a context, not a component", true)]
         public void GetComponent(string pageName, string componentId) { }
+        public System.Threading.Tasks.Task<Altinn.App.Core.Models.Expressions.ComponentContext?> GetComponentContext(string componentId, Altinn.App.Core.Models.Expressions.ComponentContext relativeContext) { }
+        [System.Obsolete("A context is not uniquely identified by componentId and rowIndexes, use GetCompon" +
+            "entContext(string, ComponentContext) instead so that we get subform data element" +
+            " as well.")]
         public System.Threading.Tasks.Task<Altinn.App.Core.Models.Expressions.ComponentContext?> GetComponentContext(string? pageName, string componentId, int[]? rowIndexes = null) { }
         public System.Threading.Tasks.Task<System.Collections.Generic.List<Altinn.App.Core.Models.Expressions.ComponentContext>> GetComponentContexts() { }
         public Altinn.Platform.Storage.Interface.Models.DataType? GetDefaultDataType() { }