Yusuf's Thoughts

DAT - Data Operators

4 min read

DAT - Data Operators

DATs (“DATa Operators”) hold text. The wiki’s definition: “DATs are used to hold text data like strings, scripts, and XML. DATs either contain multiple lines of text as in a script, or a table of rows and columns of cells, each containing one string.”

This is the only operator family with two structural shapes: a Text DAT is a single multi-line string; a Table DAT is a 2D grid of strings. Almost every DAT chooses one of these shapes and exposes the same Python access pattern across the family.

The Two Shapes

ShapeWhat it isPython access
Text DAT”free-form, multi-line ASCII text”op('script1').text (read), .text = '...' (write)
Table DAT”rows and columns of cells, each containing one string”op('table1')[r,c], op('table1')[2,'select']

Both expose the exact same node interface and connect to the same downstream ops. The shape just changes how you address content.

Sweet 16 DATs

The wiki lists these as the commonly-used DATs: Text, Table, Merge, Select, Reorder, Insert, Evaluate, Script, CHOP to, CHOP Execute, Panel Execute, DAT Execute, OSC In / UDP In, Web, Render Pick, Multi Touch In.

Practically, group them as:

  • Storage: Text, Table
  • Table manipulation: Select, Merge, Reorder, Insert, Sort, Transpose, Evaluate
  • Script holders: Text DAT (Python module), Script DAT (procedural table builder)
  • Bridges: CHOP to DAT, DAT to CHOP, Convert
  • Network IO: Web (HTTP), Web Client, Web Server, OSC In/Out, UDP In/Out, TCP/IP, Serial, MQTT
  • Input devices: MIDI Event, Multi Touch In, Render Pick, Keyboard In
  • The Execute family: see below

The Execute Family

Each Execute DAT auto-creates with a Python skeleton and fires its callbacks at specific times.

DATFires when
Execute DATProject start, on frame start, on frame end, on play state change
OP Execute DATA monitored op is created, deleted, renamed, or has its flags changed
CHOP Execute DATA monitored CHOP channel changes value, goes off-to-on, or vice versa
Parameter ExecuteA monitored parameter is changed, in any of its modes
Panel Execute DATA panel state changes (clicked, hovered, dragged, value changed)
DAT Execute DATA monitored DAT changes content (table cell edits, text appended, etc.)

See Python in TD for the full list of callback method names and signatures.

Common Patterns

Config table. Drop a Table DAT named config, fill rows with key/value cells, read it from anywhere:

rate = float(op('config')['rate', 1].val)
mode = op('config')['mode', 1].val

The .val is needed because cells are strings; cast to int/float when you need a number.

Script as a Python module. Any Text DAT containing Python can be imported as a module via the mod() global, e.g. mod('utils').my_helper(arg). The first call parses and caches the module; subsequent calls hit the cache. Edit the DAT contents and the cache invalidates, so iteration is fast.

Reactive callback. A CHOP Execute DAT pointed at a slider’s output channel runs onValueChange() only when the channel changes. Cleaner than polling in onFrameStart.

# CHOP Execute DAT, monitoring channel "Volume0"
def onValueChange(channel, sampleIndex, val, prev):
    op('mixer').par.Gain = val

Common Gotchas

  • Cells are strings. A Table DAT cell is always a string until you cast it. op('config')['rate', 1] + 1 raises a TypeError; int(op('config')['rate', 1].val) + 1 works.
  • mod() caches. A mod('utils') call uses a cached parse. If you’re editing the module DAT and the change doesn’t take effect, the cache might be stale; restarting the DAT or saving the project re-parses.
  • Web DAT pulse vs Web Client. Web DAT issues one HTTP request per pulse; Web Client DAT keeps a persistent connection open. Different tools, similar names.
  • appendRow() cooks downstream. Mutating a Table DAT from inside a callback that itself fires from a downstream op can cause re-entrant cooks. Restructure to write outside the cook chain or use run() to defer.

(y-) Next Chapter: MATs

(y) Return to DATs | (y) Return to The Operators | (y) Return to TouchDesigner | (y) Return to Home

Graph View

Backlinks