Editable JSON / YAML Tree Editor

A desktop editor for structured data files. It opens JSON, JSON Lines, YAML, and multi-document YAML as an editable tree with typed cells, schema validation, undo/redo, search, themes, and file-safe saves.

It started from Qt's Editable Tree Model example, but the current app is a practical editor for configuration files, data fixtures, schema-backed documents, and structured text that is awkward to maintain in a plain text editor.

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Quick start

Install

git clone <this repo>
cd Editable-Tree-Model-Example
python3.12 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Python 3.12+ is expected. Dependencies are pinned in requirements.txt and include PySide6, PyYAML, simplejson, gmpy2, python-dateutil, tzdata, pytest, and jsonschema[format].

Run the app

python main.py
python main.py data.json
python main.py data.yaml

You can also drag one or more local .json, .jsonl, .ndjson, .yaml, or .yml files onto the main window; each opens in its own tab.

First minute in the UI

1. Open a file with File ▸ Open or by passing a path to python main.py.
2. Edit the Value column. The editor matches the value type (spin box, datetime editor, line edit, multiline dialog, hex dialog, color picker, etc.).
3. Edit the Type column to intentionally reinterpret a value. The app preserves data when it can and uses explicit placeholders when a conversion would otherwise be ambiguous.
4. Press Ctrl+S to save. Plain Save keeps the detected file format; Save As lets you choose a different supported format.

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What it is useful for

• Inspecting and editing nested configuration without losing the shape of objects and arrays.
• Working with JSON/YAML data that has richer semantics than plain text: exact rationals, percents, dates, timezones, base64 payloads, colors, currency/unit numbers, and secret-like fields.
• Schema-guided editing: attach or auto-discover JSON Schemas, see validation issues in a dock, and jump to offending rows.
• Large or sensitive fields: open multiline, binary, and secret values in dedicated editors with warning limits and masked display.
• Bulk tree edits: move, duplicate, paste, delete, and drag/drop multiple rows with undo support.
• Fixture maintenance: round-trip JSON/YAML fixtures while keeping exact numbers and typed display/editor behaviour.

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Main features

File formats

• JSON (.json)
• JSON Lines / NDJSON (.jsonl, .ndjson)
• YAML (.yaml, .yml)
• YAML multi-document streams
• Atomic writes via os.replace
• Exact rational round-trip through gmpy2.mpq helpers

Tree editing

• Three-column tree: Name | Type | Value.
• Editable objects, arrays, primitive values, and the synthetic root.
• Multi-selection copy/cut/paste/delete/duplicate.
• Native drag-and-drop: move by default, copy with Ctrl.
• Drop cycle guard: a row cannot be moved into its own descendant.
• Context menu adapts to the selection — disabled actions are hidden rather than greyed; Expand / Collapse Recursively scopes to the selected subtree (or the whole document when the root is selected).
• Undo/redo and a History dialog powered by Qt's QUndoStack.

Tabs and files

• Multiple documents open in tabs; the title bar shows a * for unsaved changes and the tab tooltip shows the full file path.
• Reload from Disk (Ctrl+R) re-reads the current file; if the tab has unsaved edits you can Discard them, Overwrite the file with the in-memory copy, or Cancel.
• Close Tab (Ctrl+W) and Reopen Closed Tab (Ctrl+Shift+T) — last 10 closed tabs are remembered. Empty untitled tabs close without a prompt; untitled tabs that contain data prompt to save first.
• New From Clipboard (Ctrl+Space) opens a fresh tab from a JSON or YAML payload on the system clipboard.

Clipboard

• Copy as YAML text — File-menu toggle that switches the copy text format between JSON (default) and YAML. The internal MIME payload still round-trips through other tabs without loss.
• Paste accepts JSON or YAML text from other apps; bare scalars are ignored.

Typed values and editors

The app infers and displays a JsonType for each value. Common kinds:

• Numbers: integer, exact rational float, percent, currency, units.
• Text: ASCII/UTF-8 line, multiline text, empty/whitespace previews.
• Secrets: single-line and multiline values are masked in the tree.
• Dates: date, time, naive datetime, timezone datetime, UTC Z datetime.
• Binary: bytes, zlib, gzip, stored as base64-compatible text.
• Colors: rgb / rgba hex values with swatch previews.
• Structure: object, array, null, boolean.

Specialized editors include arbitrary-precision spin boxes, segmented datetime editing, multiline and hex dialogs, masked secret editors, and a color dialog.

Validation

• JSON Schema validation with jsonschema[format].
• Schema discovery from inline local $schema, sibling schema files, and persisted per-file manual bindings.
• Manual schema attach from local JSON/YAML schema files or http(s) URLs.
• Local schema files hot-reload and revalidate all bound tabs.
• YAML multi-doc validation reports issues per document.
• Validation dock shows issues, navigates to rows, and can open the schema rule for an issue.

Search, view state, and themes

• Ctrl+F recursive name/value filter; matching descendants keep their ancestors visible.
• Per-file view state: column widths, expanded rows, current row, and zoom level.
• Persistent window geometry, recent files, recent schemas, and dock layout.
• Built-in light/dark themes, type icons, follow-system mode, and optional user-theme hot reload.

Safety and ergonomics

• Confirm-before-open thresholds for very large string, multiline, binary, and attach-file operations.
• Context-menu Attach from… / Save as… for base64-like binary cells.
• Secret field masking is for shoulder-surfing/screen sharing only; secrets are still saved as plain strings on disk.

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Common workflows

Validate a document against a schema

1. Open the document.
2. Show View ▸ Validation Panel.
3. Use Schema ▸ Attach schema… in the dock or top-level Schemas menu.
4. Click an issue to jump to the row; use the issue context menu to open the matching schema rule.

Edit a large multiline value

1. Edit the value cell.
2. If the field exceeds the configured limit, confirm that you want to open the modal editor.
3. Save in the dialog; the edit is committed through undo/redo.

Work with binary/base64 data

1. Select a bytes, zlib, or gzip value.
2. Right-click the row.
3. Use Attach from… to encode a file into the cell, or Save as… to decode the cell to disk.

Configure secret detection

Secret fields are detected by word-prefixes in field names (for example password, api_key, authToken, private_key). To edit the prefix list, use File ▸ Secret word prefixes….

Find a row through the search filter

1. Press Ctrl+F and type part of a key or value.
2. Right-click a match and choose Go To — the filter clears and the editor jumps to that row.

Reload a file edited externally

If another tool changes the file on disk, press Ctrl+R. If you have unsaved edits in the tab, choose Discard to take the disk version, Overwrite to save your edits over disk, or Cancel.

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Essential shortcuts

Shortcut	Action
Ctrl+N / Ctrl+O	New / Open
Ctrl+Space	New tab from clipboard (JSON or YAML)
Ctrl+R	Reload current tab from disk
Ctrl+S / Ctrl+Shift+S	Save / Save As
Ctrl+W / Ctrl+Shift+T	Close current tab / Reopen last closed tab
Ctrl+F	Focus filter
F2 or Enter	Edit current cell
Ctrl+I / Ctrl+Shift+I	Insert sibling before / after
Del	Remove selection
Ctrl+D	Duplicate selection
Ctrl+C / Ctrl+X / Ctrl+V	Copy / Cut / Paste
Ctrl+Shift+V	Multi-paste: insert clipboard entries after selected targets
Ctrl+Alt+V	Multi-paste: replace selected target values
Alt+↑ / Alt+↓	Move selection up / down
Ctrl+Alt+↑ / Ctrl+Alt+↓	Promote selection out of its parent
Ctrl+Alt+S	Sort keys under selected object
Ctrl++ / Ctrl+- / Ctrl+0	Zoom in / out / reset

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Development

Run tests

QT_QPA_PLATFORM=offscreen pytest

The suite currently collects 1023 tests. A small set of color-scheme tests is known to be platform-sensitive under Qt's offscreen QPA plugin because offscreen does not round-trip QStyleHints.setColorScheme like real desktop platforms do.

Lint and format

make lint

The lint target runs autoflake, isort, and black with the repository configuration.

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Project documentation

• ai-memory/repo-map.md — dense module-by-module map for agents and contributors.
• ai-memory/pros-n-cons.md — current strengths, caveats, and gaps.
• ai-memory/todo-n-fixme.md — active open work only.
• ai-memory/history.md — archived resolved phase/feature history.
• plans/ — feature plans and definitions of done for larger changes.

Dev setup

Activate the repo-local git hooks (run once after cloning):

make dev-setup

This installs .githooks/pre-commit, which rejects new getattr / hasattr calls outside the small allowlist documented in plans/10-allowlist-and-precommit-hook.md (jsontream/__init__.py, validation/error_adapter.py, app/runtime_compat.py). Tests may use reflection but must justify each call with an inline # allow: <reason> comment. CI runs the same check via make check-no-reflection.