Truncate large messages displayed in log grid

src/Aspire.Dashboard/Components/Pages/StructuredLogs.razor

@@ -144,7 +144,8 @@
                                         <AspireTemplateColumn ColumnId="@TimestampColumn" ColumnManager="@_manager" Title="@Loc[nameof(Dashboard.Resources.StructuredLogs.StructuredLogsTimestampColumnHeader)]" TooltipText="@(context => FormatHelpers.FormatDateTime(TimeProvider, context.TimeStamp, MillisecondsDisplay.Full, CultureInfo.CurrentCulture))" Tooltip="true">
                                             @FormatHelpers.FormatTimeWithOptionalDate(TimeProvider, context.TimeStamp, MillisecondsDisplay.Truncated)
                                         </AspireTemplateColumn>
-                                        <AspireTemplateColumn ColumnId="@MessageColumn" ColumnManager="@_manager" Title="@Loc[nameof(Dashboard.Resources.StructuredLogs.StructuredLogsMessageColumnHeader)]" Tooltip="true" TooltipText="(e) => e.Message">
+                                        <AspireTemplateColumn ColumnId="@MessageColumn" ColumnManager="@_manager" Title="@Loc[nameof(Dashboard.Resources.StructuredLogs.StructuredLogsMessageColumnHeader)]">
+                                            @* Tooltip is displayed by the message GridValue instance *@
                                             <LogMessageColumnDisplay FilterText="@(ViewModel.FilterText)" LogEntry="@context" />
                                         </AspireTemplateColumn>
                                         <AspireTemplateColumn ColumnId="@TraceColumn" ColumnManager="@_manager" Title="@Loc[nameof(Dashboard.Resources.StructuredLogs.StructuredLogsTraceColumnHeader)]">

src/Aspire.Dashboard/Components/ResourcesGridColumns/LogMessageColumnDisplay.razor

@@ -3,11 +3,13 @@
 @using Aspire.Dashboard.Extensions
 @using Aspire.Dashboard.Otlp.Model
 @using Aspire.Dashboard.Resources
+@using Aspire.Dashboard.Utils
 
 @inject IStringLocalizer<StructuredLogs> Loc
 
-<GridValue Value="@LogEntry.Message"
+<GridValue Value="@FormatHelpers.TruncateText(LogEntry.Message, FormatHelpers.ColumnMaximumTextLength)"
            ValueDescription="@Loc[nameof(StructuredLogs.StructuredLogsMessageColumnHeader)]"
+           ToolTip="@FormatHelpers.TruncateText(LogEntry.Message, FormatHelpers.TooltipMaximumTextLength)"
            EnableHighlighting="true"
            HighlightText="@FilterText"
            StopClickPropagation="true">

src/Aspire.Dashboard/Utils/FormatHelpers.cs

@@ -18,6 +18,11 @@ public enum MillisecondsDisplay
 
 internal static partial class FormatHelpers
 {
+    // Limit size of very long data that is written in large grids.
+    public const int ColumnMaximumTextLength = 250;
+    public const int TooltipMaximumTextLength = 1500;
+    public const string Ellipsis = "…";
+
     // There are an unbound number of CultureInfo instances so we don't want to use it as the key.
     // Someone could have also customized their culture so we don't want to use the name as the key.
     // This struct contains required information from the culture that is used in cached format strings.
@@ -133,4 +138,19 @@ public static string FormatNumberWithOptionalDecimalPlaces(double value, int max
         };
         return value.ToString(formatString, provider ?? CultureInfo.CurrentCulture);
     }
+
+    public static string TruncateText(string? text, int maxLength)
+    {
+        if (string.IsNullOrEmpty(text))
+        {
+            return string.Empty;
+        }
+
+        if (text.Length <= maxLength)
+        {
+            return text;
+        }
+
+        return string.Concat(text.AsSpan(0, maxLength - Ellipsis.Length), Ellipsis);
+    }
 }

tests/Aspire.Dashboard.Tests/FormatHelpersTests.cs

@@ -82,6 +82,16 @@ public void FormatDateTime_WithMilliseconds_NewZealandCulture(string expected, M
         Assert.Equal(expected, FormatHelpers.FormatDateTime(CreateTimeProvider(), date, includeMilliseconds, cultureInfo: CultureInfo.GetCultureInfo("en-NZ")), ignoreWhiteSpaceDifferences: true, ignoreCase: true);
     }
 
+    [Theory]
+    [InlineData(null, 5, "")]
+    [InlineData("", 5, "")]
+    [InlineData("abcdef", 5, "abcd" + FormatHelpers.Ellipsis)]
+    [InlineData("abcdef", 10, "abcdef")]
+    public void TruncateText(string? initialText, int maxLength, string expected)
+    {
+        Assert.Equal(expected, FormatHelpers.TruncateText(initialText, maxLength: maxLength));
+    }
+
     private static DateTime GetLocalDateTime(string value)
     {
         Assert.True(DateTime.TryParseExact(value, "o", CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out var date));