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Fix SystemTextJsonUtils.GetFailurePath #1973

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Merged
exyi merged 2 commits into from
Dec 29, 2025
Merged

Fix SystemTextJsonUtils.GetFailurePath #1973

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78922b6
Fix SystemTextJsonUtils.GetFailurePath
exyi Dec 28, 2025
ae3926f
Fix JsonUtils.GetFailurePath for root arrays and empty values
exyi Dec 29, 2025
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91 changes: 45 additions & 46 deletions src/Framework/Framework/Utils/SystemTextJsonUtils.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,56 +14,55 @@ static class SystemTextJsonUtils
/// <summary> Returns the property path to an unfinished JSON value </summary>
public static string[] GetFailurePath(ReadOnlySpan<byte> data)
{
// TODO: tests
var reader = new Utf8JsonReader(data, false, default);
var path = new Stack<(string? name, int index)>();
var isArray = false;
int arrayIndex = 0;
while (reader.Read())
// configure higher max depth than default (64), to correctly display path of
// the "max depth exceeded" error
var options = new JsonReaderOptions { MaxDepth = 196 };
var reader = new Utf8JsonReader(data, false, new JsonReaderState(options));
if (!reader.Read())
return [];
return GetFailurePathInternal(ref reader) ?? throw new Exception("No error in specified JSON");
}

private static string[]? GetFailurePathInternal(ref Utf8JsonReader reader)
{
if (reader.TokenType == JsonTokenType.None)
return [];
else if (reader.TokenType == JsonTokenType.StartObject)
{
if (!reader.Read()) return [];
string? lastProperty = null;
while (reader.TokenType == JsonTokenType.PropertyName)
{
lastProperty = reader.GetString().NotNull();
if (!reader.Read())
return [lastProperty];
if (GetFailurePathInternal(ref reader) is {} nestedError)
return [lastProperty, ..nestedError];
if (!reader.Read())
return [];
}
if (reader.TokenType != JsonTokenType.EndObject)
return lastProperty is null ? [] : [lastProperty];
return null;
}
else if (reader.TokenType == JsonTokenType.StartArray)
{
switch (reader.TokenType)
if (!reader.Read()) return ["0"];
int index = 0;
while (reader.TokenType != JsonTokenType.EndArray)
{
case JsonTokenType.StartObject:
if (isArray) {
isArray = false;
path.Push((null, arrayIndex));
}
break;
case JsonTokenType.Comment:
break;
case JsonTokenType.StartArray:
isArray = true;
arrayIndex = 0;
break;
case JsonTokenType.EndArray:
isArray = false;
break;
case JsonTokenType.True:
case JsonTokenType.False:
case JsonTokenType.Number:
case JsonTokenType.String:
case JsonTokenType.Null:
case JsonTokenType.EndObject:
if (!isArray) {
var old = path.Pop();
if (old.name is null) {
isArray = true;
arrayIndex = old.index + 1;
}
}
else {
arrayIndex++;
}
break;
case JsonTokenType.PropertyName:
path.Push((reader.GetString()!, -1));
break;
case JsonTokenType.None:
goto Done;
if (GetFailurePathInternal(ref reader) is {} nestedError)
return [$"{index}", ..nestedError];
index++;
if (!reader.Read() || reader.TokenType == JsonTokenType.None)
return [$"{index}"];
}
return null;
}
else
{
return null;
}
Done:
return path.Reverse().Select(n => n.name ?? n.index.ToString()).ToArray();
}

public static JsonElement? GetPropertyOrNull(this in JsonElement jsonObj, ReadOnlySpan<byte> name) =>
Expand Down
110 changes: 110 additions & 0 deletions src/Tests/ViewModel/JsonUtilsTests.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,110 @@
using Microsoft.VisualStudio.TestTools.UnitTesting;
using DotVVM.Framework.ViewModel.Serialization;
using DotVVM.Framework.Utils;

namespace DotVVM.Framework.Tests.ViewModel
{
[TestClass]
public class JsonUtilsTests
{
const string IrrelevantObjectStart = """
"notthis": { "alsonotthis": "lala", "another": 1 },
"alsonot": [ 1, 2, 3, { "irrelevant": 1, "nope": null, "neither_this": true, "alsonot": false }, [], [[[[], []]]] ],
""";

[DataTestMethod]
[DataRow("{\"viewModel\":", "viewModel")]
[DataRow(
$$"""
{
"test": [
{ "notthis": 1, "myprop": 5},
{
"notthis": 1,
"myprop":
""",
"test/1/myprop"
)]
[DataRow(
$$"""
{ {{IrrelevantObjectStart}}
"test": [
{ "notthis": 1, "myprop": 5},
{
"notthis": 1,
"myprop":
""",
"test/1/myprop"
)]
[DataRow(
$$"""
{ {{IrrelevantObjectStart}}
"test": [ { {{IrrelevantObjectStart}} "myprop":{
""",
"test/0/myprop"
)]
[DataRow(
$$"""
{ {{IrrelevantObjectStart}}
"test2":
""",
"test2"
)]
[DataRow(
$$"""
{ {{IrrelevantObjectStart}}
"test3": { "ok": [1, 2, 3], "alsofine": {}
""",
"test3"
)]
[DataRow(
$$"""
{
"items": [
{ "id": 1 },
""",
"items/1"
)]
[DataRow(
$$"""
{
"items": [
{
"nested": [
1,
2,
""",
"items/0/nested/2"
)]
[DataRow(
$$"""
{
"items": [
""",
"items/0"
)]
[DataRow(
"""
{ "arr": [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[1, 2], []]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]],
"prop": 1
""",
"prop"
)]
[DataRow(
"""
[
1, 2,
{ "ok": true },
{ "not_ok":
""",
"3/not_ok"
)]
[DataRow(" ", "")]
public void GetInvalidJsonErrorPath(string json, string expectedPath)
{
var utf8 = StringUtils.Utf8.GetBytes(json);
var path = SystemTextJsonUtils.GetFailurePath(utf8);
Assert.AreEqual(expectedPath, string.Join("/", path));
}
}
}