python / python/cpython

difflib adding an additional html column when making tables using difflib.HtmlDiff()

Abierto
#117,943 4 comentarios 0 reacciones 0 asignados Ver en GitHub

Nadie ha tomado este issue todavía.

stdlib type-bug
Lenguaje dominante
Python
Estrellas
77.2k
Forks
36k
Métricas de PR pendientes

Descripción

Bug report

Bug description:

I am working with the python library difflib and specifically the class HtmlDiff. For some reason, the function make_table is adding a blank column in when generating an HTML table, throwing off difference highlights and defeating the entire purpose of the diff function alltogether.

Input python function:

# diff_tool.py

import argparse
import difflib
import sys

from pathlib import Path


def create_diff(output_file: Path = None):
        
    # short list of strings to compare, nonproblematic (see expected output)
    thing1 = ["this", "that"]
    thing2 = ["thiis", "that2"]

    # longer list of strings to compare, mirroring the problematic data (see actual output)
    file_2 = ['Ab', 
    'my_id: ID1234, attribute: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f , name: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f ', 
    'my_id: ID5678, attribute: abcde ghijklm opyrst vwxyz bc efghij lmnopyr tuv xyzab defabcde ghijklmno yrstuvwxyza cdefghijklmnop rstuvw yz b defab defgh jklmnop rstuvwxyz bcd fghijkl nopyr tuvwxyza cdefabcd fghijkl no yrs uvwxyzabcd fghij l n, name: ab defghi klmnopy stuvwxy abcde ghijklm op']
                   
    file_2_new = ['Abcdefghijklmn', 
    'my_id: ID1234, attribute: abcde ghijklm opyrst vwxyz bc efghij lmnopyr tuv xyzab defabcde ghijklmno yrstuvwxyza cdefghijklmnop rstuvw yz b defab defgh jklmnop rstuvwxyz bcd fghijkl nopyr tuvwxyza cdefabcd fghijkl no yrs uvwxyzabcd fghij l n, name: ab defghi klmnopy stuvwxy abcde ghijklm op', 
    'my_id: ID5678, attribute: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f , name: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f ']

    # if output HTML file option at command line
    if output_file:
    
        # create HtmlDiff Object
        my_html = difflib.HtmlDiff()
        
        # make table with problematic data, delta1 is a string
        delta1 = my_html.make_table(
            file_2, file_2_new, "table1A" , "table1B"
        )     

        # replace nowrap tags and weird space characters
        delta1 = delta1.replace(" ", " ")
        delta1 = delta1.replace("nowrap=\"nowrap\"", "")

        # html header which goes at beggining of html file
        html_header = '''

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>
<body style="background-color:white;">
<head>
    <meta http-equiv="Content-Type"
          content="text/html; charset=utf-8" />
    <title></title>
    <style type="text/css">
        table.diff {font-family:Courier; color: black; border:medium;table-layout: auto; width: 96%; word-wrap: break-word; margin-left: auto; margin-right: auto;}
        td.diff_header {text-align:left}
        .diff_header {background-color:#e0e0e0}
        .diff_next {background-color:#c0c0c0}
        .diff_add {background-color:#aaffaa}
        .diff_chg {background-color:#ffff77}
        .diff_sub {background-color:#ffaaaa}
        .widthA{width:1%}
        .widthB{width:7%}
        .widthC{width:40%}
        .element_title{color: black; text-align:center}
        .element_diff{color: black; width: 96%; margin-left: auto; margin-right: auto}
    </style>
</head>

'''
        # html footer which goes at the end of html file
        html_footer = '''
        </body>

</html>
        '''
        
        # open output file path and write header, table and footer
        with open(output_file, "w") as f:
            f.write(html_header)
            f.write(delta1)
            f.write(html_footer)
    

def main():

    # parse command line option for output HTML file
    parser = argparse.ArgumentParser()
    parser.add_argument("--html", help="specify html to write to")
    args = parser.parse_args()


    if args.html:
        output_file = Path(args.html)
    else:
        output_file = None

    # call create_diff function which compares two lists of strings
    # and returns a formatted HTML table comparing them
    create_diff(output_file)


if __name__ == "__main__":
    main()

Output HTML file with problematic data:



<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>
<body style="background-color:white;">
<head>
    <meta http-equiv="Content-Type"
          content="text/html; charset=utf-8" />
    <title></title>
    <style type="text/css">
        table.diff {font-family:Courier; color: black; border:medium;table-layout: auto; width: 96%; word-wrap: break-word; margin-left: auto; margin-right: auto;}
        td.diff_header {text-align:left}
        .diff_header {background-color:#e0e0e0}
        .diff_next {background-color:#c0c0c0}
        .diff_add {background-color:#aaffaa}
        .diff_chg {background-color:#ffff77}
        .diff_sub {background-color:#ffaaaa}
        .widthA{width:1%}
        .widthB{width:7%}
        .widthC{width:40%}
        .element_title{color: black; text-align:center}
        .element_diff{color: black; width: 96%; margin-left: auto; margin-right: auto}
    </style>
</head>


    <table class="diff" id="difflib_chg_to0__top"
           cellspacing="0" cellpadding="0" rules="groups" >
        <colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
        <colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
        <thead><tr><th class="diff_next"><br /></th><th colspan="2" class="diff_header">table1A</th><th class="diff_next"><br /></th><th colspan="2" class="diff_header">table1B</th></tr></thead>
        <tbody>
            <tr><td class="diff_next" id="difflib_chg_to0__0"><a href="#difflib_chg_to0__top">t</a></td><td class="diff_header" id="from0_1">1</td><td ><span class="diff_sub">Ab</span></td><td class="diff_next"><a href="#difflib_chg_to0__top">t</a></td><td class="diff_header" id="to0_1">1</td><td ><span class="diff_add">Abcdefghijklmn</span></td></tr>
            <tr><td class="diff_next"></td><td class="diff_header" id="from0_2">2</td><td ><span class="diff_sub">my_id: ID1234, attribute: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f , name: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f </span></td><td class="diff_next"></td><td class="diff_header"></td><td ></td></tr>
            <tr><td class="diff_next"></td><td class="diff_header" id="from0_3">3</td><td >my_id: ID<span class="diff_chg">5678</span>, attribute: abcde ghijklm opyrst vwxyz bc efghij lmnopyr tuv xyzab defabcde ghijklmno yrstuvwxyza cdefghijklmnop rstuvw yz b defab defgh jklmnop rstuvwxyz bcd fghijkl nopyr tuvwxyza cdefabcd fghijkl no yrs uvwxyzabcd fghij l n, name: ab defghi klmnopy stuvwxy abcde ghijklm op</td><td class="diff_next"></td><td class="diff_header" id="to0_2">2</td><td >my_id: ID<span class="diff_chg">1234</span>, attribute: abcde ghijklm opyrst vwxyz bc efghij lmnopyr tuv xyzab defabcde ghijklmno yrstuvwxyza cdefghijklmnop rstuvw yz b defab defgh jklmnop rstuvwxyz bcd fghijkl nopyr tuvwxyza cdefabcd fghijkl no yrs uvwxyzabcd fghij l n, name: ab defghi klmnopy stuvwxy abcde ghijklm op</td></tr>
            <tr><td class="diff_next"></td><td class="diff_header"></td><td ></td><td class="diff_next"></td><td class="diff_header" id="to0_3">3</td><td ><span class="diff_add">my_id: ID5678, attribute: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f , name: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f </span></td></tr>
        </tbody>
    </table>
        </body>

</html>

The problematic line in the HTML is:

<tr><td class="diff_next"></td><td class="diff_header" id="from0_2">2</td><td ><span class="diff_sub">my_id: ID1234, attribute: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f , name: abcd fghijklmn py stuvwx zabc efg ijklmnopy st vwxy abcd f </span></td><td class="diff_next"></td><td class="diff_header"></td><td ></td></tr>

Where there is an extra <td ></td> at the end, adding an extra column.

This is what the table looks like with the unwanted column

This is what the table is supposed to look like when the columns are aligned correctly

I have tried changing the length of the string, checking for invisible characters, removing colons. There is something wrong with the strings that I am providing as input which throws off the make_table function. I have provided make_table with longer strings and the output was just fine. The behavior is very inconsistent.

Thanks for the help.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Guía de contribución

Abrir la guía de contribución

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Línea de trabajo

Comienza con la reproducción en diff_tool.py y el punto de entrada difflib.HtmlDiff().make_table, utilizando las listas file_2 y file_2_new proporcionadas. Inspecciona cómo se ensamblan las filas y columnas generadas; después, verifica que la entrada problemática ya no produzca una celda vacía adicional y añade cobertura de regresión para el caso reproducido.

Escrito por el modelo de indexación a partir del texto del issue.

Evaluación

Stack tecnológico
python
Área
tooling
Tipo de issue
Error
Dificultad
3/5
Tiempo estimado
1-2 días
Estado de actividad
Estancado
Claridad
Bastante claro
Aptitud para principiantes
42/100

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.