Pine Script Float to String: Type Conversion and str.tostring() Guide

Formatting patterns with str.tostring in Pine Script v6

Formatting numbers accurately is essential when constructing on-chart labels, table cells, or dynamic JSON alert payloads for automated webhook execution.

Complete Pine Script v6 script: JSON webhook and status label generator

This indicator formats a label and builds a sample JSON message after ATR is available. The signal is a confirmed close crossing above its EMA; the BUY/SELL input only labels the message and does not implement a short-entry rule. It places no orders. Create a TradingView alert for alert() calls, then inspect the received payload against your receiver schema before enabling any execution.

//@version=6
indicator("String Formatting & Webhook Builder [v6]", overlay = true)

// Inputs
float stopMultiplier = input.float(1.5, "Stop ATR Multiplier", minval = 0.5)
string actionType = input.string("BUY", "Order Action", options = ["BUY", "SELL"])

// Calculations
float atrVal = ta.atr(14)
float stopPrice = actionType == "BUY" ? close - (atrVal * stopMultiplier) : close + (atrVal * stopMultiplier)

// Format numbers with tick precision
string priceStr = str.tostring(close, format.mintick)
string stopStr = str.tostring(stopPrice, format.mintick)
string timeStr = str.format_time(time, "yyyy-MM-dd HH:mm", "UTC")

// Construct multi-line on-chart dashboard text using str.format
string displayText = str.format(
     "Status: {0}\nPrice: {1}\nStop: {2}\nTime: {3}", 
     actionType, priceStr, stopStr, timeStr)

// Render on-chart label on current bar
var label statusLabel = na
if barstate.islast
    label.delete(statusLabel)
    statusLabel := label.new(
         bar_index, high, displayText, 
         color = color.navy, textcolor = color.white, 
         style = label.style_label_down)

// Escape the two JSON string metacharacters that can occur in a symbol.
string symbolJson = str.replace_all(str.replace_all(syminfo.tickerid, "\\", "\\\\"), '"', '\\"')
string jsonPayload = '{"action":"' + actionType + '","symbol":"' + symbolJson + '","price":' + priceStr + ',"stop":' + stopStr + ',"timestamp":"' + timeStr + '"}'

// A sample close-confirmed alert, not a complete trading system.
float ema20 = ta.ema(close, 20)
bool signal = ta.crossover(close, ema20)
if signal and barstate.isconfirmed and not na(atrVal)
    alert(jsonPayload, alert.freq_once_per_bar_close)

Percentage units and JSON validity

format.percent appends a percent sign to a value already expressed in percentage points. For a fractional return such as 0.045, multiply by 100 first or use a custom trailing-percent mask such as #.##%. An unavailable value formats as NaN, which is not a valid unquoted JSON number; the alert below waits for ATR. Its UTC time string is a display format, not a timezone-bearing ISO 8601 timestamp.

String concatenation: Plus (+) operator vs str.format

When joining multiple pieces of text in TradingView Pine Script, developers choose between two approaches:

• str.format templating: Recommended for complex strings and JSON payloads. It keeps templates readable by replacing numbered tokens ({0}, {1}) with corresponding variables.
• Plus (+) concatenation: Best for short combinations like "RSI: " + str.tostring(rsiVal). Note that all joined elements must already be of type string; joining a float directly with a plus sign causes a compiler error.
• Literal braces: str.format uses apostrophe-quoted text for literal braces, not doubled braces. The example concatenates JSON fragments instead and escapes backslashes and quotation marks in the symbol string.
• Converting strings back to numbers: Use str.tonumber(str). If the string cannot be parsed as a valid number, the function cleanly returns na.

Handling type casting errors in Pine Script v6

Watch out for these common type compatibility issues:

• Implicit conversion missing: Pine Script does not automatically convert numbers to strings inside string expressions. You must explicitly call str.tostring(x).
• Legacy tostring() syntax: In v4 and earlier, tostring() had no namespace. Pine Script v5 and v6 require str.tostring().
• Color to string: Colors cannot be converted to strings with str.tostring(). Manage color states using conditional branches rather than string tags.