Convert nested JSON to CSV

Question

I am converting a nested JSON object with more than 10 levels to CSV file in C# .NET.

I have been using JavaScriptSerializer().Deserialize(json)

Answer 1

There's an inconsistency in your request: you want a row to be generated for the root object, which has children, but you don't want a row to be generated for the "F3[2]" object, which also has children. So it sounds like your rule is, "print a row for an object with at least one primitive-value property, as long as that object is either the root object or does not have descendant objects with at a least one primitive-value property". That's a little tricky, but can be done with LINQ to JSON

        var obj = JObject.Parse(json);

        // Collect column titles: all property names whose values are of type JValue, distinct, in order of encountering them.
        var values = obj.DescendantsAndSelf()
            .OfType()
            .Where(p => p.Value is JValue)
            .GroupBy(p => p.Name)
            .ToList();

        var columns = values.Select(g => g.Key).ToArray();

        // Filter JObjects that have child objects that have values.
        var parentsWithChildren = values.SelectMany(g => g).SelectMany(v => v.AncestorsAndSelf().OfType().Skip(1)).ToHashSet();

        // Collect all data rows: for every object, go through the column titles and get the value of that property in the closest ancestor or self that has a value of that name.
        var rows = obj
            .DescendantsAndSelf()
            .OfType()
            .Where(o => o.PropertyValues().OfType().Any())
            .Where(o => o == obj || !parentsWithChildren.Contains(o)) // Show a row for the root object + objects that have no children.
            .Select(o => columns.Select(c => o.AncestorsAndSelf()
                .OfType()
                .Select(parent => parent[c])
                .Where(v => v is JValue)
                .Select(v => (string)v)
                .FirstOrDefault())
                .Reverse() // Trim trailing nulls
                .SkipWhile(s => s == null)
                .Reverse());

        // Convert to CSV
        var csvRows = new[] { columns }.Concat(rows).Select(r => string.Join(",", r));
        var csv = string.Join("\n", csvRows);

        Console.WriteLine(csv);

Using

public static class EnumerableExtensions
{
    // http://stackoverflow.com/questions/3471899/how-to-convert-linq-results-to-hashset-or-hashedset
    public static HashSet ToHashSet(this IEnumerable source)
    {
        return new HashSet(source);
    }
}

Which outputs:

F1,F2,E1,E2,D1,D2
1,2
1,2,3,4
1,2,5,6
1,2,7,8,9,10