Firebase 限制字符串字符的Firestore规则

如何在Firestore规则中限制用户名的字符？我试着一个接一个地验证每个字符，但没有成功

     function validateChar1(sername) {

     return sername[0] == "a" || sername[0] == "b" || sername[0] == "c" || sername[0] == "d" || sername[0] == "e" || sername[0] == "f" || sername[0] == "g" || sername[0] == "h"
        || sername[0] == "i" || sername[0] == "j" || sername[0] == "k" || sername[0] == "l" || sername[0] == "m" || sername[0] == "n" || sername[0] == "o" || sername[0] == "p"
  || sername[0] == "q" || sername[0] == "r" || sername[0] == "s" || sername[0] == "t" || sername[0] == "u" || sername[0] == "v" || sername[0] == "w" || sername[0] == "x"
  || sername[0] == "y" || sername[0] == "z" || sername[0] == "0" || sername[0] == "1" || sername[0] == "2" || sername[0] == "3" || sername[0] == "4" || sername[0] == "5" 
  || sername[0] == "6" || sername[0] == "7" || sername[0] == "8" || sername[0] == "9" || sername[0] == "." || sername[0] == "_"
    }

    function validateChar3(sername) {

    return sername[2] == "a" || sername[2] == "b" || sername[2] == "c" || sername[2] == "d" || sername[2] == "e" || sername[2] == "f" || sername[2] == "g" || sername[2] == "h"
        || sername[2] == "i" || sername[2] == "j" || sername[2] == "k" || sername[2] == "l" || sername[2] == "m" || sername[2] == "n" || sername[2] == "o" || sername[2] == "p"
  || sername[2] == "q" || sername[2] == "r" || sername[2] == "s" || sername[2] == "t" || sername[2] == "u" || sername[2] == "v" || sername[2] == "w" || sername[2] == "x"
  || sername[2] == "y" || sername[2] == "z" || sername[2] == "0" || sername[2] == "1" || sername[2] == "2" || sername[2] == "3" || sername[2] == "4" || sername[2] == "5" 
  || sername[2] == "6" || sername[2] == "7" || sername[2] == "8" || sername[2] == "9" || sername[2] == "." || sername[2] == "_" || sername.size() < 3;
    }



    function validateUsername(username) {

    return validateChar1(username) && validateChar2(username) && validateChar3(username) && validateChar4(username) && validateChar5(username) &&
        validateChar6(username) && validateChar7(username) && validateChar8(username) && validateChar9(username) && validateChar10(username) &&
  validateChar11(username) && validateChar12(username) && validateChar13(username) && validateChar14(username) && validateChar15(username) 
    }

函数validateChar1（sername）{
返回sername[0]=“a”| sername[0]=“b”| sername[0]=“c”| sername[0]=“d”| sername[0]=“e”| sername[0]=“f”| sername[0]=“g”| sername[0]=“h”
||sername[0]=“i”| | sername[0]=“j”| | sername[0]=“k”| | sername[0]=“l”| | sername[0]=“m”| | sername[0]=“n”| sername[0]=“o”| sername[0]=“p”
||sername[0]=“q”| | sername[0]=“r”| | sername[0]=“s”| | sername[0]=“t”| | sername[0]=“u”| | sername[0]=“v”| | sername[0]=“w”| sername[0]=“x”
||sername[0]=“y”| | sername[0]=“z”| | sername[0]=“0”| | sername[0]=“1”| | sername[0]=“2”| | sername[0]=“3”| sername[0]=“4”| sername[0]=“5”
||sername[0]=“6”| | sername[0]=“7”| | sername[0]=“8”| | sername[0]=“9”| | sername[0]=”| | sername[0]=“|”
}
函数validateChar3（sername）{
返回sername[2]=“a”| sername[2]=“b”| sername[2]=“c”| sername[2]=“d”| sername[2]=“e”| sername[2]=“f”| sername[2]=“g”| sername[2]=“h”
||sername[2]=“i”| sername[2]=“j”| sername[2]=“k”| sername[2]=“l”| sername[2]=“m”| sername[2]=“n”| sername[2]=“o”| sername[2]=“p”
||sername[2]=“q”| sername[2]=“r”| sername[2]=“s”| sername[2]=“t”| sername[2]=“u”| sername[2]=“v”| sername[2]=“w”| sername[2]=“x”
||sername[2]=“y”| | sername[2]=“z”| | sername[2]=“0”| | sername[2]=“1”| | sername[2]=“2”| sername[2]=“3”| sername[2]=“4”| sername[2]=“5”
||sername[2]=“6”| | sername[2]=“7”| | sername[2]=“8”| | sername[2]=“9”| | sername[2]=“2”| | sername.size（）<3；
}
函数validateUsername（用户名）{
返回validateChar1（用户名）和validateChar2（用户名）和validateChar3（用户名）和validateChar4（用户名）和validateChar5（用户名）&&
validateChar6（用户名）和validateChar7（用户名）和validateChar8（用户名）和validateChar9（用户名）和validateChar10（用户名）&&
validateChar11（用户名）和validateChar12（用户名）和validateChar13（用户名）和validateChar14（用户名）和validateChar15（用户名）
}

看一看。在

字符串

部分，您将找到

匹配项

。这允许您对照正则表达式检查值。您可以创建一个正则表达式，以仅验证用户名允许的字符。

请查看。在

字符串

部分，您将找到

匹配项

。这允许您对照正则表达式检查值。您可以创建一个正则表达式，只验证用户名允许的字符。

您如何使用这些函数？@DougStevenson用户名可以有15个字符长。这意味着我有15个类似于上面两个的函数，不同的是我检查字符串的大小是否比相应的字符短。最后，我有一个函数可以检查所有字符是否有效。请编辑您的问题，以准确显示您的规则是如何显示的，而不仅仅是这些函数。您如何使用这些函数？@DougStevenson用户名可以是15个字符长。这意味着我有15个类似于上面两个的函数，不同的是我检查字符串的大小是否比相应的字符短。最后，我有一个函数，可以检查所有字符是否有效。请编辑您的问题，以准确显示规则的显示方式，而不仅仅是这些函数。