WIP: Add alias ["value", 0] in addition to ["argv", 0]

* Move values to a separate interface added to context `IContextValueAccessor`
* Provide `["value"]` as a shortcut for `["dataModel", ["argv", 0]]`

src/Altinn.App.Core/Features/Validation/Default/ExpressionValidator.cs

@@ -1,3 +1,4 @@
+using System.Text;
 using System.Text.Json;
 using Altinn.App.Core.Helpers.DataModel;
 using Altinn.App.Core.Internal.App;
@@ -136,23 +137,21 @@ internal async Task<List<ValidationIssue>> ValidateFormData(
                 {
                     continue;
                 }
+                var valueAccessor = new ExpressionContextValueAccessor(
+                    resolvedField,
+                    await evaluatorState.GetModelData(resolvedField)
+                );
                 var context = new ComponentContext(
                     component: null,
                     rowIndices: DataModel.GetRowIndices(resolvedField.Field),
                     rowLength: null,
-                    dataElementIdentifier: resolvedField.DataElementIdentifier
+                    dataElementIdentifier: resolvedField.DataElementIdentifier,
+                    contextValueAccessor: valueAccessor
                 );
-                var positionalArguments = new object[] { resolvedField };
+
                 foreach (var validation in validations)
                 {
-                    await RunValidation(
-                        evaluatorState,
-                        validationIssues,
-                        resolvedField,
-                        context,
-                        positionalArguments,
-                        validation
-                    );
+                    await RunValidation(evaluatorState, validationIssues, resolvedField, context, validation);
                 }
             }
         }
@@ -165,7 +164,6 @@ private async Task RunValidation(
         List<ValidationIssue> validationIssues,
         DataReference resolvedField,
         ComponentContext context,
-        object[] positionalArguments,
         ExpressionValidation validation
     )
     {
@@ -179,8 +177,7 @@ ExpressionValidation validation
             var validationResult = await ExpressionEvaluator.EvaluateExpression(
                 evaluatorState,
                 validation.Condition.Value,
-                context,
-                positionalArguments
+                context
             );
             switch (validationResult)
             {
@@ -433,4 +430,36 @@ out JsonElement validationsObject
         }
         return expressionValidations;
     }
+
+    private class ExpressionContextValueAccessor(DataReference reference, object? value) : IContextValueAccessor
+    {
+        public object? GetValue(ExpressionFunction function, ReadOnlySpan<object?> args)
+        {
+            if (function != ExpressionFunction.value)
+            {
+                throw new ExpressionEvaluatorTypeErrorException(
+                    $"Invalid function for value/argv expression ({function})"
+                );
+            }
+            switch (args)
+            {
+                case []:
+                    return value;
+                case [0.0]:
+                case ["0"]:
+                case ["reference"]:
+                    return reference;
+                default:
+                    var sb = new StringBuilder();
+                    foreach (var arg in args)
+                    {
+                        sb.Append(", ");
+                        sb.Append(arg);
+                    }
+                    throw new ExpressionEvaluatorTypeErrorException(
+                        $"Invalid arguments for value/argv expression ([\"value\"{sb}])"
+                    );
+            }
+        }
+    }
 }

src/Altinn.App.Core/Helpers/DataModel/DataModel.cs

@@ -85,6 +85,16 @@ DataElementIdentifier defaultDataElementIdentifier
         return modelWrapper.GetModelData(key.Field, rowIndexes);
     }
 
+    /// <summary>
+    /// Get model data based on an explicit data reference
+    /// </summary>
+    public async Task<object?> GetModelData(DataReference dataReference)
+    {
+        var model = await _dataAccessor.GetFormData(dataReference.DataElementIdentifier);
+        var modelWrapper = new DataModelWrapper(model);
+        return modelWrapper.GetModelData(dataReference.Field);
+    }
+
     /// <summary>
     /// Get the count of data elements set in a group (enumerable)
     /// </summary>

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

@@ -58,8 +58,7 @@ bool defaultReturn
     public static async Task<object?> EvaluateExpression(
         LayoutEvaluatorState state,
         Expression expr,
-        ComponentContext context,
-        object[]? positionalArguments = null
+        ComponentContext context
     )
     {
         if (!expr.IsFunctionExpression)
@@ -69,7 +68,7 @@ bool defaultReturn
         var args = new object?[expr.Args.Count];
         for (var i = 0; i < args.Length; i++)
         {
-            args[i] = await EvaluateExpression(state, expr.Args[i], context, positionalArguments);
+            args[i] = await EvaluateExpression(state, expr.Args[i], context);
         }
         // ! TODO: should find better ways to deal with nulls here for the next major version
         var ret = expr.Function switch
@@ -98,7 +97,7 @@ bool defaultReturn
             ExpressionFunction.round => Round(args),
             ExpressionFunction.upperCase => UpperCase(args),
             ExpressionFunction.lowerCase => LowerCase(args),
-            ExpressionFunction.argv => Argv(args, positionalArguments),
+            ExpressionFunction.value => ContextValueLookup(args, context),
             ExpressionFunction.gatewayAction => state.GetGatewayAction(),
             ExpressionFunction.language => state.GetLanguage() ?? "nb",
             _ => throw new ExpressionEvaluatorTypeErrorException($"Function \"{expr.Function}\" not implemented"),
@@ -110,12 +109,13 @@ bool defaultReturn
     {
         if (args is [DataReference dataReference])
         {
-            return await DataModel(
-                new ModelBinding() { Field = dataReference.Field },
-                dataReference.DataElementIdentifier,
-                context.RowIndices,
-                state
-            );
+            // Only allow IConvertible types to be returned from data model
+            // Objects and arrays should return null
+            return await state.GetModelData(dataReference) switch
+            {
+                IConvertible c => c,
+                _ => null,
+            };
         }
         var key = args switch
         {
@@ -192,7 +192,7 @@ LayoutEvaluatorState state
             args.Select(a =>
                 a switch
                 {
-                    string s => s,
+                    string s => s, // concat must not convert "NULL" to null
                     _ => ToStringForEquals(a),
                 }
             )
@@ -534,28 +534,19 @@ private static (double?, double?) PrepareNumericArgs(object?[] args)
         return string.Equals(ToStringForEquals(args[0]), ToStringForEquals(args[1]), StringComparison.Ordinal);
     }
 
-    private static object Argv(object?[] args, object[]? positionalArguments)
+    private static object? ContextValueLookup(ReadOnlySpan<object?> args, ComponentContext? context)
     {
-        if (args.Length != 1)
-        {
-            throw new ExpressionEvaluatorTypeErrorException($"Expected 1 argument(s), got {args.Length}");
-        }
-
-        var index = (int?)PrepareNumericArg(args[0]);
-        if (!index.HasValue)
-        {
-            throw new ExpressionEvaluatorTypeErrorException($"Expected number, got value \"{args[0]}\"");
-        }
-
-        if (positionalArguments == null)
+        IContextValueAccessor? contextValueAccessor = null;
+        while (context != null && contextValueAccessor == null)
         {
-            throw new ExpressionEvaluatorTypeErrorException("No positional arguments available");
+            contextValueAccessor = context.ContextValueAccessor;
+            context = context.Parent;
         }
-        if (index < 0 || index >= positionalArguments.Length)
+        if (contextValueAccessor == null)
         {
-            throw new ExpressionEvaluatorTypeErrorException($"Index {index} out of range");
+            throw new ExpressionEvaluatorTypeErrorException("Tried to evaluate ");
         }
 
-        return positionalArguments[index.Value];
+        return contextValueAccessor.GetValue(ExpressionFunction.value, args);
     }
 }

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

@@ -136,6 +136,14 @@ private static bool CompareRowIndexes(int[]? targetRowIndexes, int[]? sourceRowI
         return true;
     }
 
+    /// <summary>
+    /// Get model data from an explicit data reference
+    /// </summary>
+    public async Task<object?> GetModelData(DataReference dataReference)
+    {
+        return await _dataModel.GetModelData(dataReference);
+    }
+
     /// <summary>
     /// Get field from dataModel with key and context
     /// </summary>

src/Altinn.App.Core/Models/Expressions/ComponentContext.cs

@@ -20,10 +20,12 @@ public ComponentContext(
         int[]? rowIndices,
         int? rowLength,
         DataElementIdentifier dataElementIdentifier,
-        IEnumerable<ComponentContext>? childContexts = null
+        IEnumerable<ComponentContext>? childContexts = null,
+        IContextValueAccessor? contextValueAccessor = null
     )
     {
         DataElementIdentifier = dataElementIdentifier;
+        ContextValueAccessor = contextValueAccessor;
         Component = component;
         RowIndices = rowIndices;
         _rowLength = rowLength;
@@ -123,6 +125,11 @@ public async Task<BitArray> GetHiddenRows(LayoutEvaluatorState state)
     /// </summary>
     public DataElementIdentifier DataElementIdentifier { get; }
 
+    /// <summary>
+    /// Accessor for the ["value"] expression (used in expression validation and when expressions are used in filters)
+    /// </summary>
+    public IContextValueAccessor? ContextValueAccessor { get; }
+
     /// <summary>
     /// Get all children and children of children of this componentContext (not including this)
     /// </summary>

src/Altinn.App.Core/Models/Expressions/ExpressionConverter.cs

@@ -1,3 +1,4 @@
+using System.Buffers;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -48,11 +49,7 @@ private static Expression ReadArray(ref Utf8JsonReader reader, JsonSerializerOpt
             throw new JsonException("Function name in expression should be string");
         }
 
-        var stringFunction = reader.GetString();
-        if (!Enum.TryParse<ExpressionFunction>(stringFunction, ignoreCase: false, out var functionEnum))
-        {
-            throw new JsonException($"Function \"{stringFunction}\" not implemented");
-        }
+        var functionEnum = ParseFunctionName(ref reader);
 
         var args = new List<Expression>();
 
@@ -64,6 +61,47 @@ private static Expression ReadArray(ref Utf8JsonReader reader, JsonSerializerOpt
         return new Expression(functionEnum, args);
     }
 
+    private static ExpressionFunction ParseFunctionName(ref Utf8JsonReader reader)
+    {
+        var functionSpan = reader.HasValueSequence ? reader.ValueSequence.ToArray() : reader.ValueSpan;
+        return functionSpan switch
+        {
+            [100, 97, 116, 97, 77, 111, 100, 101, 108] => ExpressionFunction.dataModel,
+            [99, 111, 109, 112, 111, 110, 101, 110, 116] => ExpressionFunction.component,
+            [105, 110, 115, 116, 97, 110, 99, 101, 67, 111, 110, 116, 101, 120, 116] =>
+                ExpressionFunction.instanceContext,
+            [105, 102] => ExpressionFunction.@if,
+            [102, 114, 111, 110, 116, 101, 110, 100, 83, 101, 116, 116, 105, 110, 103, 115] =>
+                ExpressionFunction.frontendSettings,
+            [99, 111, 110, 99, 97, 116] => ExpressionFunction.concat,
+            [117, 112, 112, 101, 114, 67, 97, 115, 101] => ExpressionFunction.upperCase,
+            [108, 111, 119, 101, 114, 67, 97, 115, 101] => ExpressionFunction.lowerCase,
+            [99, 111, 110, 116, 97, 105, 110, 115] => ExpressionFunction.contains,
+            [110, 111, 116, 67, 111, 110, 116, 97, 105, 110, 115] => ExpressionFunction.notContains,
+            [99, 111, 109, 109, 97, 67, 111, 110, 116, 97, 105, 110, 115] => ExpressionFunction.commaContains,
+            [101, 110, 100, 115, 87, 105, 116, 104] => ExpressionFunction.endsWith,
+            [115, 116, 97, 114, 116, 115, 87, 105, 116, 104] => ExpressionFunction.startsWith,
+            [101, 113, 117, 97, 108, 115] => ExpressionFunction.equals,
+            [110, 111, 116, 69, 113, 117, 97, 108, 115] => ExpressionFunction.notEquals,
+            [103, 114, 101, 97, 116, 101, 114, 84, 104, 97, 110, 69, 113] => ExpressionFunction.greaterThanEq,
+            [108, 101, 115, 115, 84, 104, 97, 110] => ExpressionFunction.lessThan,
+            [108, 101, 115, 115, 84, 104, 97, 110, 69, 113] => ExpressionFunction.lessThanEq,
+            [103, 114, 101, 97, 116, 101, 114, 84, 104, 97, 110] => ExpressionFunction.greaterThan,
+            [115, 116, 114, 105, 110, 103, 76, 101, 110, 103, 116, 104] => ExpressionFunction.stringLength,
+            [114, 111, 117, 110, 100] => ExpressionFunction.round,
+            [97, 110, 100] => ExpressionFunction.and,
+            [111, 114] => ExpressionFunction.or,
+            [110, 111, 116] => ExpressionFunction.not,
+            [118, 97, 108, 117, 101] => ExpressionFunction.value,
+            [97, 114, 103, 118] => ExpressionFunction.value, // "argv" works for compatibility
+            [103, 97, 116, 101, 119, 97, 121, 65, 99, 116, 105, 111, 110] => ExpressionFunction.gatewayAction,
+            [108, 97, 110, 103, 117, 97, 103, 101] => ExpressionFunction.language,
+            _ => throw new JsonException(
+                $"Function \"{System.Text.Encoding.UTF8.GetString(functionSpan)}\" not implemented"
+            ),
+        };
+    }
+
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, Expression value, JsonSerializerOptions options)
     {

src/Altinn.App.Core/Models/Expressions/ExpressionFunctionEnum.cs

@@ -134,9 +134,12 @@ public enum ExpressionFunction
     not,
 
     /// <summary>
-    /// Returns a positional argument
+    /// Get the value from context (eg the value from expression validation, or the option to filter)
     /// </summary>
-    argv,
+    /// <remarks>
+    /// This vas previously named argv for expression validation and it works for compatibility reasons
+    /// </remarks>
+    value,
 
     /// <summary>
     /// Get the action performed in task prior to bpmn gateway

src/Altinn.App.Core/Models/Expressions/IContextValueAccessor.cs

@@ -0,0 +1,18 @@
+namespace Altinn.App.Core.Models.Expressions;
+
+/// <summary>
+/// Provide an implementation for the ["value", ?] expression
+/// The expression is special, because it is only valid in contexts where there exists a value
+/// * Expression validation (`["value"]` is the value to validate)
+/// * Filtering (["value"] is the value that is should be compared)
+/// </summary>
+public interface IContextValueAccessor
+{
+    /// <summary>
+    /// Get the value from the context
+    /// </summary>
+    /// <param name="function">The function that was called</param>
+    /// <param name="args">List of arguments for the expression</param>
+    /// <returns>The value</returns>
+    object? GetValue(ExpressionFunction function, ReadOnlySpan<object?> args);
+}

test/Altinn.App.Core.Tests/Features/Validators/expression-validation-tests/shared/many-errors.json

@@ -43,20 +43,20 @@
         {
           "message": "email must be real",
           "severity": "error",
-          "condition": ["contains", ["dataModel", ["argv", 0]], "fake"]
+          "condition": ["contains", ["dataModel", ["argv", "reference"]], "fake"]
         },
         {
           "ref": "str-len",
           "condition": [
             "lessThan",
-            ["stringLength", ["dataModel", ["argv", 0]]],
+            ["stringLength", ["value"]],
             20
           ]
         },
         {
           "message": "email must contain @",
           "severity": "error",
-          "condition": ["notContains", ["dataModel", ["argv", 0]], "@"]
+          "condition": ["notContains", ["dataModel", ["value", 0]], "@"]
         }
       ]
     },

test/Altinn.App.Core.Tests/LayoutExpressions/CommonTests/shared-tests/functions/concat/specialStrings.json

@@ -0,0 +1,5 @@
+{
+  "name": "Special strings must not be lowercased",
+  "expression": ["concat", "TRUE", "FALSE", "true", "false", "Null", "null", "NULL", "undefined", "UNDEFINED"],
+  "expects": "TRUEFALSEtruefalseNullnullNULLundefinedUNDEFINED"
+}