Concat (Flowgraph Node)

Overview

• Node Name: Concat
• Category: simple
• File: extensions/flowgraph/nodes/string/stringconcat.lua
• Obsolete: Use the Format String node instead.

Combines all input values into a single concatenated string.

Pin Schema

Input Pins

Output Pins

Behavior

• init() - Initializes empty output and input cache. Enables pin saving.
• _executionStarted() - Clears the input cache.
• updateCache() - Compares current input pin values against the cached values. Returns true if any input changed. Converts all non-nil, non-false values to strings via tostring().
• work() - If inputs changed (dirty), concatenates all cached values using table.concat with no separator.
• onLink() / onUnlink() - Triggers pin cleanup to maintain auto-expanding behavior.
• cleanupPins() - Ensures exactly one empty trailing input pin exists. Removes excess empty pins at the end, adds one if none exist.

How It Works

1. Connect values to input pins. New empty pins auto-appear as you link.
2. All non-nil, non-false input values are converted to strings and concatenated in order.
3. The result updates only when inputs change (dirty-checking optimization).

-- Example:
-- value1 = "Hello "
-- value2 = "World"
-- value3 = "!"
-- Output: "Hello World!"

-- Nil/false inputs are skipped
-- value1 = "Score: "
-- value2 = 42       -- converted via tostring()
-- Output: "Score: 42"

Notes

• Obsolete - The Format String node is preferred for new flowgraphs.
• Auto-pin increment doesn't work with hardcoded pins.
• Boolean values must be stringified manually.

Key Dependencies

• Lua built-in table.concat, tostring

Additional Methods

C:drawMiddle(builder, style)

Custom ImGui drawing in the middle section of the node in the editor.

Parameters:

• builder
• style

See Also

• Format String (Flowgraph Node) - Related reference
• Match String (Flowgraph Node) - Related reference
• SubString (Flowgraph Node) - Related reference
• FlowGraph Guide - Guide