Pine Script v4保存代码报itemType未定义问题咨询

问题根因 #

该报错是Pine Script v4的特性限制导致：security()函数不支持接收字符串类型的返回值。你自定义的sFunc()将字符串变量rsievent作为返回值之一，通过security()调用时触发了类型解析异常。

修复方案 #

方案1：删除不需要的字符串返回值 #

如果你不需要用到rsievent的事件记录逻辑，直接移除该返回值即可，修改后代码如下：

//@version=4
study("Screen", shorttitle = 'Screen', overlay = false)

// RSI Params
rsi_length     = input(14, title = "RSI Length")
rsi_overbought = input(70, title = "RSI Overbought Level")
rsi_oversold   = input(30, title = "RSI Oversold Level") // 顺便修正原代码此处标题的笔误

// Symbols 
// There is a limit of 40 security calls so only 40 symbols at the same time is possible
s01 = input('AAPL',  type=input.symbol)

sFunc() => 
    rsi     = rsi(close, rsi_length)
    cond    = rsi > rsi_overbought or rsi < rsi_oversold
    value   = rsi
    [value, cond]

[v01, c01] = security(s01, timeframe.period, sFunc())
plot(v01, "v01", color=color.green)

方案2：升级到Pine Script v5 #

Pine Script v5已经支持security()函数传递字符串类型的返回值，仅需将脚本开头的版本声明改为//@version=5，同步适配v5的语法即可：

//@version=5
indicator("Screen", shorttitle = 'Screen', overlay = false)

// RSI Params
rsi_length     = input.int(14, title = "RSI Length")
rsi_overbought = input.int(70, title = "RSI Overbought Level")
rsi_oversold   = input.int(30, title = "RSI Oversold Level")

// Symbols 
s01 = input.symbol('AAPL')

sFunc() => 
    rsievent = ''
    rsi_val     = ta.rsi(close, rsi_length)
    cond    = rsi_val > rsi_overbought or rsi_val < rsi_oversold
    value   = rsi_val
    rsievent := ta.crossover(rsi_val, 40) ? rsievent + 'RSICROSSOVER40'  + '\n' : rsievent
    [value, cond, rsievent]

[v01, c01, b01] = request.security(s01, timeframe.period, sFunc())
plot(v01, "v01", color=color.green)

方案3：v4版本下用数字编码替代字符串 #

如果必须保留v4版本，可将事件内容转换为数字编码传递，后续根据编码映射回事件含义即可，示例：

sFunc() => 
    // 事件编码定义：0=无事件，1=RSI上穿40
    event_code = 0
    rsi     = rsi(close, rsi_length)
    cond    = rsi > rsi_overbought or rsi < rsi_oversold
    value   = rsi
    event_code := crossover(rsi, 40) ? 1 : event_code
    [value, cond, event_code]

[v01, c01, event01] = security(s01, timeframe.period, sFunc())
// 使用时判断event01的数值即可匹配对应事件

内容的提问来源于stack exchange，提问作者Govind Shukla