"Misplaced \noalign" error with datatool

Question

Attempting to compile the following file gives the following error:

! Misplaced \noalign.
\pagebreak ->\noalign 
                      {\ifnum `}=0\fi \@testopt {\LT@no@pgbk -}4
l.47 \end{letter}

I don't understand why. Making minor changes to the csv file xx.csv makes this error go away. For example, change mm to m. Alternatively, change mm to 11.

Alternatively, adding a comma to the end of the string 2014.02.26,26,2014.11.12.tm in

\PrintDocTableParekh[2014.02.26,26,2014.11.12.tm]{newbDB}{Documents}

thus changing it to 2014.02.26,26,2014.11.12.tm, also makes the error go away.

\documentclass[12pt]{letter}
\usepackage{longtable}
\usepackage[verbose]{datatool}
\usepackage{array}
\usepackage{url}

\newcounter{tabenum}\setcounter{tabenum}{0}
\newcommand{\colhead}[1]{\multicolumn{1}{>{\bfseries}l}{#1}}
\newcommand{\nextnuml}[1]{\refstepcounter{tabenum}\thetabenum.\label{#1}}
\newcommand*{\checkmissing}[1]{\DTLifnull{#1}{}{#1}}
\signature{Someone}
\newcommand{\PrintDocTableParekh}[3][]{%
 % #1 = list of rowIDs
 % #2 = database to search
 % #3 =caption
  \begin{longtable}{r l p{1.5in} c c p{2.5in}}
    \caption{#3}\\
   & \colhead{Date} & \colhead{Filename} & \colhead{From} & \colhead{To} & \colhead{Subject}\\\hline\endhead
    \DTLforeach
    [\ifblank{#1}{\boolean{true}}{\DTLisSubString{#1}{\RowID}}]
    {#2}{%
      \RowID=RowID,%
      \Date=Date,%
      \Filename=Filename,%
      \From=From,%
      \To=To,%
      \Subject=Subject%
    }{%
      \nextnuml{\RowID} & \Date & {\bfseries\expandafter\url\expandafter{\Filename} } & \checkmissing{\From} & \checkmissing{\To} & \Subject \\
    }%
  \end{longtable}
}%

\begin{filecontents*}{xx.csv}
2014.02.26,       26 Feb 2014      , something.txt     ,      ,    ,    ,subject
2014.11.12.tm,    12 Nov 2014      , something.txt     , XXX  , YY ,    , subject
mm, date, ,,,, subject
\end{filecontents*}

\begin{document}
\begin{letter}{}
  \opening{xx,}
  \closing{Yours Sincerely,}
  \DTLloaddb[noheader,keys={RowID,Date,Filename,From,To,Email,Subject}]{newbDB}{xx.csv}
  \PrintDocTableParekh[2014.02.26,26,2014.11.12.tm]{newbDB}{Documents}

\end{letter}
\end{document}

Answer 1

There seems to be a problem with \DTLifSubString when used within \DTLforeach. (This includes using \DTLisSubString in the conditional argument.) The use of letter and longtable are obfuscating matters, so here's a trimmed down version:

\documentclass{article}

\usepackage{datatool}

\begin{filecontents*}{xx.csv}
2014.02.26
2014.11.12.tm
mm
\end{filecontents*}

\newcommand*{\ifcontainsrowid}[2]{%
 \ifblank{#1}{#2}%
 {%
   \DTLifSubString{#1}{\RowID}{#2}{}%
 }%
}    

\begin{document}

\DTLloaddb[noheader,keys={RowID}]{newbDB}{xx.csv}

\DTLforeach*{newbDB}{\RowID=RowID}%
{%
   \ifcontainsrowid{2014.02.26,26,2014.11.12.tm}%
   {%
      \RowID
   }
}%

\end{document}

This causes a different error message:

Runaway argument?
\expandafter \dtl@ifsingle \expandafter {\dtl@first }{\expandafter \@dtl@testif
substring \ETC.
! Paragraph ended before \dtl@getfirst was complete.
<to be read again> 
                   \par

But it stems from the same problem. I haven't worked out what's causing it yet, but I've been away for a week and need to catch up on things so I haven't had much of a chance to investigate yet. You can get around it by using a different command, for example \IfSubStr from the xstring package:

\documentclass{article}

\usepackage{datatool}
\usepackage{xstring}

\begin{filecontents*}{xx.csv}
2014.02.26
2014.11.12.tm
mm
\end{filecontents*}

\newcommand*{\ifcontainsrowid}[2]{%
 \ifblank{#1}{#2}%
 {%
   %\DTLifSubString{#1}{\RowID}{#2}{}%
   \IfSubStr{#1}{\RowID}{#2}{}%
 }%
}


\begin{document}

\DTLloaddb[noheader,keys={RowID}]{newbDB}{xx.csv}

\DTLforeach*{newbDB}{\RowID=RowID}%
{%
   \ifcontainsrowid{2014.02.26,26,2014.11.12.tm}%
   {%
      \RowID
   }
}%

\end{document}

Update: This bug has been fixed in v2.23.