JsonCompactColumnizer.cs

using System;
using System.Collections.Generic;
using System.Linq;

using LogExpert;

using Newtonsoft.Json.Linq;

namespace JsonColumnizer;

/// <summary>
///     This Columnizer can parse JSON files.
/// </summary>
public class JsonCompactColumnizer : JsonColumnizer, IColumnizerPriority
{
    #region Public methods

    public override string GetName ()
    {
        return "JSON Compact Columnizer";
    }

    public override string GetDescription ()
    {
        return "A JSON columnier for Serilog.Formatting.Compact format.";
    }

    public override void Selected (ILogLineColumnizerCallback callback)
    {
        ColumnList.Clear();
        // Create column header with cached column list.

        foreach (var col in TagDict.Keys)
        {
            ColumnList.Add(new JsonColumn(TagDict[col]));
        }
    }

    public override Priority GetPriority (string fileName, IEnumerable<ILogLine> samples)
    {
        var result = Priority.NotSupport;
        if (fileName.EndsWith("json", StringComparison.OrdinalIgnoreCase))
        {
            result = Priority.WellSupport;
        }

        if (samples != null && samples.Any())
        {
            try
            {
                var line = samples.First();
                var json = ParseJson(line);
                if (json != null)
                {
                    var columns = SplitJsonLine(samples.First(), json);
                    if (columns.ColumnValues.Length > 0 && Array.Exists(columns.ColumnValues, x => !string.IsNullOrEmpty(x.FullValue)))
                    {
                        result = Priority.PerfectlySupport;
                    }
                }
            }
            catch (Exception)
            {
                // Ignore errors when determine priority.
            }
        }

        return result;
    }

    #endregion

    #region Private Methods

    protected Dictionary<string, string> TagDict { get; set; } = new()
    {
        {"@t", "Timestamp"},
        {"@l", "Level"},
        {"@m", "Message"},
        {"@x", "Exception"},
        {"@i", "Event id"},
        {"@r", "Renderings"},
        {"@mt", "Message Template"},
    };

    protected override IColumnizedLogLine SplitJsonLine (ILogLine line, JObject json)
    {
        List<IColumn> returnColumns = [];
        var cLogLine = new ColumnizedLogLine { LogLine = line };

        var columns = json.Properties().Select(property => new ColumnWithName { FullValue = property.Value.ToString(), ColumnName = property.Name.ToString(), Parent = cLogLine }).ToList();

        //
        // Always rearrage the order of all json fields within a line to follow the sequence of columnNameList.
        // This will make sure the log line displayed correct even the order of json fields changed.
        //
        foreach (var column in TagDict.Keys)
        {
            if (column.StartsWith('@'))
            {
                var existingColumn = columns.Find(x => x.ColumnName == column);

                if (existingColumn != null)
                {
                    returnColumns.Add(new Column() { FullValue = existingColumn.FullValue, Parent = cLogLine });
                    continue;
                }

                // Fields that is missing in current line should be shown as empty.
                returnColumns.Add(new Column() { FullValue = "", Parent = cLogLine });
            }
        }

        cLogLine.ColumnValues = [.. returnColumns];

        return cLogLine;
    }

    #endregion
}