[01415] Fix DataTable footer concatenated currency formatting

src/Ivy.Tests/Views/DataTables/DataTableFooterFormatTests.cs

@@ -0,0 +1,103 @@
+using Ivy;
+
+namespace Ivy.Tests.Views.DataTables;
+
+public class DataTableFooterFormatTests
+{
+    private record SalesRow(string Product, decimal Amount, double Rate, int Count);
+
+    private static IQueryable<SalesRow> SampleData() =>
+        new[]
+        {
+            new SalesRow("A", 10_543.56m, 0.152, 100),
+            new SalesRow("B", 150_587.95m, 0.348, 200),
+        }.AsQueryable();
+
+    private static List<string> GetFooter(DataTableBuilder<SalesRow> builder, string columnName)
+    {
+        // Access the private _columns dictionary via reflection
+        var flags = System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance;
+        var columnsField = builder.GetType().GetField("_columns", flags)!;
+        var columnsObj = columnsField.GetValue(builder)!;
+
+        // Get the InternalColumn via the dictionary's Item property (indexer)
+        var dictType = columnsObj.GetType();
+        var itemProp = dictType.GetProperty("Item")!;
+        var internalColumn = itemProp.GetValue(columnsObj, [columnName])!;
+
+        // Get the Column property from InternalColumn
+        var columnProp = internalColumn.GetType().GetProperty("Column")!;
+        var column = (DataTableColumn)columnProp.GetValue(internalColumn)!;
+        return column.Footer ?? [];
+    }
+
+    [Fact]
+    public void Footer_WithCurrencyFormat_FormatsAggregateWithCurrencySymbol()
+    {
+        var builder = SampleData().ToDataTable()
+            .Format(x => x.Amount, NumberFormatStyle.Currency, precision: 2, currency: "USD")
+            .Footer(x => x.Amount, "Total", values => values.Sum());
+
+        var footer = GetFooter(builder, "Amount");
+        Assert.Single(footer);
+        Assert.Contains("$", footer[0]);
+        Assert.Contains("161,131.51", footer[0]);
+        Assert.StartsWith("Total: ", footer[0]);
+    }
+
+    [Fact]
+    public void Footer_WithPercentFormat_FormatsAsPercentage()
+    {
+        var builder = SampleData().ToDataTable()
+            .Format(x => x.Rate, NumberFormatStyle.Percent, precision: 1)
+            .Footer(x => x.Rate, "Avg", values => values.Average());
+
+        var footer = GetFooter(builder, "Rate");
+        Assert.Single(footer);
+        // Average of 0.152 and 0.348 = 0.25 → 25.0%
+        Assert.Contains("25.0", footer[0]);
+        Assert.Contains("%", footer[0]);
+    }
+
+    [Fact]
+    public void Footer_WithDecimalFormat_FormatsWithGroupingSeparators()
+    {
+        var builder = SampleData().ToDataTable()
+            .Format(x => x.Count, NumberFormatStyle.Decimal, precision: 0)
+            .Footer(x => x.Count, "Total", values => values.Sum());
+
+        var footer = GetFooter(builder, "Count");
+        Assert.Single(footer);
+        Assert.Equal("Total: 300", footer[0]);
+    }
+
+    [Fact]
+    public void Footer_WithoutFormatStyle_PassesThroughToString()
+    {
+        var builder = SampleData().ToDataTable()
+            .Footer(x => x.Count, "Total", values => values.Sum());
+
+        var footer = GetFooter(builder, "Count");
+        Assert.Single(footer);
+        Assert.Equal("Total: 300", footer[0]);
+    }
+
+    [Fact]
+    public void Footer_MultipleAggregates_WithCurrencyFormat_EachGetsFormatted()
+    {
+        var builder = SampleData().ToDataTable()
+            .Format(x => x.Amount, NumberFormatStyle.Currency, precision: 2, currency: "USD")
+            .Footer(x => x.Amount, new (string, Func<IEnumerable<decimal>, object>)[]
+            {
+                ("Sum", values => values.Sum()),
+                ("Avg", values => values.Average()),
+            });
+
+        var footer = GetFooter(builder, "Amount");
+        Assert.Equal(2, footer.Count);
+        Assert.Contains("$", footer[0]);
+        Assert.Contains("161,131.51", footer[0]);
+        Assert.Contains("$", footer[1]);
+        Assert.Contains("80,565.76", footer[1]);
+    }
+}

src/Ivy/Views/DataTables/DataTableBuilder.cs

@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations;
+using System.Globalization;
 using System.Linq.Expressions;
 using System.Reflection;
 using Ivy.Core.Helpers;
@@ -182,7 +183,7 @@ public DataTableBuilder<TModel> Footer<TValue>(
         var selector = field.Compile();
         var values = GetOrCreateFooterValueList(field, selector);
         var result = aggregateFunc(values);
-        var footerText = $"{label}: {result}";
+        var footerText = $"{label}: {FormatFooterValue(column.Column, result)}";
         column.Column.Footer ??= [];
         column.Column.Footer.Add(footerText);
         return this;
@@ -196,13 +197,61 @@ public DataTableBuilder<TModel> Footer<TValue>(
         var selector = field.Compile();
         var values = GetOrCreateFooterValueList(field, selector);
         var footerValues = aggregates
-            .Select(agg => $"{agg.Label}: {agg.AggregateFunc(values)}")
+            .Select(agg => $"{agg.Label}: {FormatFooterValue(column.Column, agg.AggregateFunc(values))}")
             .ToList();
         column.Column.Footer ??= [];
         column.Column.Footer.AddRange(footerValues);
         return this;
     }
 
+    private static string FormatFooterValue(DataTableColumn column, object value)
+    {
+        if (value is IFormattable formattable && column.FormatStyle.HasValue)
+        {
+            var style = column.FormatStyle.Value;
+            var precision = column.Precision ?? 2;
+
+            if (style == NumberFormatStyle.Currency || style == NumberFormatStyle.Accounting)
+            {
+                var currency = column.Currency ?? "USD";
+                var culture = GetCultureForCurrency(currency);
+                return formattable.ToString($"C{precision}", culture);
+            }
+
+            var invariant = CultureInfo.InvariantCulture;
+            return style switch
+            {
+                NumberFormatStyle.Percent => formattable.ToString($"P{precision}", invariant),
+                NumberFormatStyle.Decimal => formattable.ToString($"N{precision}", invariant),
+                _ => value.ToString() ?? ""
+            };
+        }
+
+        return value.ToString() ?? "";
+    }
+
+    private static CultureInfo GetCultureForCurrency(string isoCurrencyCode)
+    {
+        try
+        {
+            foreach (var ci in CultureInfo.GetCultures(CultureTypes.SpecificCultures))
+            {
+                var region = new RegionInfo(ci.Name);
+                if (string.Equals(region.ISOCurrencySymbol, isoCurrencyCode, StringComparison.OrdinalIgnoreCase))
+                    return ci;
+            }
+        }
+        catch
+        {
+            // Fall through to default
+        }
+
+        // Default to en-US for unknown currencies
+        var fallback = new CultureInfo("en-US");
+        fallback.NumberFormat.CurrencySymbol = isoCurrencyCode;
+        return fallback;
+    }
+
     private List<TValue> GetOrCreateFooterValueList<TValue>(
         Expression<Func<TModel, TValue>> field,
         Func<TModel, TValue> compiledSelector)