PRO_JSON

Bugfixes and improvements of Codesys PRO_JSON library by Pro Electric (Author: TVM)

Source: https://forge.codesys.com/lib/pro-json/home/Home/

• Ver 19: array issue fixes, rootless json
• Ver 20: Ver 19 + multidimensional arrays
• Ver 21: Ver 20 + option to add single long string field to the end of the root object.
• PRO_JSON File IO - set of FBs to read/save JSON structs to text files. Compatible with last version.

Version 19 : Array errors fix, rootless json

Array Export Repair

Symptom: JSON export produced malformed structure around arrays (wrong closes / misplaced fields), especially with nested arrays and object depth changes.

Root cause: JSONVAR.FB_Init did not correctly close dropped array/object levels when path depth shifted down between adjacent variables.

Fix: Added shift-down closure logic in FB_Init to explicitly mark EndArray/EndObject on dropped levels and preserve proper InArray/InObject state.

Result: Array/object boundaries became valid; nested array output no longer leaked sibling fields into wrong objects.

Rootless Option (secondary feature/fix)

Goal: Allow JSON output without top wrapper object ({"codesysVarName": {...}}), i.e. emit root content directly.

Implementation: Added Rootless switch in STRUCT_TO_JSON and guarded wrapper-level open/close/name emission using root-level filtering.

Related fix: Corrected close-bracket behavior under IgnoreNull=TRUE to avoid orphan ] tokens in rootless/minimal output paths.

Result:

• Rootless=FALSE: legacy wrapped JSON preserved.
• Rootless=TRUE: valid rootless JSON emitted.
• IgnoreNull=TRUE/FALSE both generate valid JSON.

Version 20: Multidimensional arrays

• Added robust multidimensional array support to both STRUCT_TO_JSON (compose) and JSON_TO_STRUCT (parse).
• Array handling is now vector-based (ArrayDimCount + ArrayIndexes[]) instead of single-index only.
• Legacy ArrayIndex is still supported as a compatibility mirror (no API break).
• Compose no longer flattens normal 2D/3D arrays into duplicate-key output; nested JSON arrays are emitted correctly.
• Overflow dimensions beyond GPL_JSON.MAX_ARRAY_DIMENSIONS are now policy-driven (flatten-to-last vs non-flatten branch).
• Existing Rootless and IgnoreNull behavior remains unchanged.
• No public interface/signature changes; patch is backward-compatible for existing 1D and non-array usage.

Version 21: Long Custom Field Support

• Added optional custom root-level string field injection in STRUCT_TO_JSON for long texts.
• Custom field is configured before compose (via SetCustomField method)
• Custom value is passed by pointer to String, so no large JSONVAR value copy is required.
• Added explicit precheck for buffer capacity before custom-field append; returns error if it would exceed GPL_JSON.MAX_JSON_STRING.
• Added JSON escaping while writing pointer text (", , control chars), preserving valid JSON output.
• Existing behavior is unchanged when custom field is not enabled.

PRO_JSON File IO

• set of FBs to read/save JSON structs to text files. Compatible with last version.
• Import it as PLCopen XML (seems to be imported to the top 'Application')