.NET: Fix JSON arrays of objects parsed as empty records when no schema is defined

[L. Elaine Dazzio (LEDazzio01)]

Motivation and Context

Fixes#4195 — JSON arrays of objects are parsed as empty records when no schema is defined in declarative workflows.

When an InvokeAzureAgent action returns a JSON object containing an array of objects, and the output is captured via responseObject, all nested object properties are silently dropped. Each object in the array becomes {}. Subsequent Foreach iteration over the array crashes with an unhandled workflow failure.

Description

Root cause: In JsonDocumentExtensions.cs, the ParseTable method's DetermineElementType() function creates a schema-bound VariableType with an empty (non-null) schema when targetType.Schema is null:

// Before (broken)JsonValueKind.Object=> VariableType.Record(targetType.Schema?.Select(kvp =>(kvp.Key,kvp.Value))??[]),

When targetType.Schema is null, the ?? [] fallback passes an empty collection to VariableType.Record(), creating a VariableType with Schema set to an empty FrozenDictionary (non-null, count = 0). Downstream, ParseRecord checks targetType.Schema is null and takes the ParseSchema path (which iterates over zero fields), silently discarding all JSON properties.

Fix: Check targetType.HasSchema (which correctly handles empty schemas) and fall back to VariableType.RecordType when no schema is defined:

// After (fixed)JsonValueKind.Object=> targetType.HasSchema?VariableType.Record(targetType.Schema!.Select(kvp =>(kvp.Key,kvp.Value))):VariableType.RecordType,

This ensures ParseRecord takes the dynamic ParseValues() path that preserves all JSON properties.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? No — this is a bug fix that restores expected behavior.

[L. Elaine Dazzio (LEDazzio01)]

I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.

[Copilot]

Pull request overview

Fixes a declarative workflow JSON parsing bug where arrays of objects could be inferred as “empty-schema records,” causing nested object properties to be dropped when no schema is defined.

Changes:

• Updates ParseTable element-type inference to use VariableType.RecordType when the target list type has no schema, avoiding creation of an empty (non-null) schema.
• Uses targetType.HasSchema to decide when to propagate a schema into inferred record element types.

[L. Elaine Dazzio (LEDazzio01)]

Chris (@crickman) — Unit tests are ready! I just pushed 7f3182f with two regression tests added to JsonDocumentExtensionsTests.cs:

1. ParseRecord_ObjectWithArrayOfObjects_NoSchema_PreservesNestedProperties — The exact bug repro from .NET: [Bug]: Declarative workflow - JSON arrays of objects parsed as empty records when no schema is defined #4195: parses { "items": [ {"name":"Alice","role":"Engineer"}, ... ] } with VariableType.RecordType (no schema) and asserts all nested properties are preserved (would have returned [{}, {}, {}] before the fix).

2. ParseList_ArrayOfObjects_NoSchema_PreservesProperties — Exercises ParseList directly with VariableType.ListType (no schema) on an array of objects, verifying properties aren't dropped during element-type inference.

Both follow the existing Arrange/Act/Assert pattern and reference the issue in their XML doc comments. Let me know if you'd like any adjustments!