How to format xml or html's attributes into multiple lines instead of lining up on one line?

Question

I'm using plugin Chiel92/vim-autoformat auto formatting xml files. So the default format program used for xml file is tidy. The way it formats xml file is like below:

<List id='list' items='{/sss}' mode='{device&gt;/listMode}' noDataText='{i18n&gt;masterListNoDataText}' select='onSelect' growing='true' growingScrollToLoad='true'>
    <items>
        <ObjectListItem type='{device&gt;/listItemType}' press='onSelect' title='{Name}' number='{ path: "Price", formatter: "exp.ind.cli.util.Formatter.currencyValue" }' numberUnit='USD'></ObjectListItem>
    </items>
</List>

As you can see the attributes of the tags are on one line, and it can last very long even goes out of the screen. What I want is all the attributes to be formatted on separate lines( vertically aligned ).

<List id='list' 
    items='{/sss}' 
    mode='{device&gt;/listMode}' 
    noDataText='{i18n&gt;masterListNoDataText}' 
    select='onSelect' 
    growing='true' 
    growingScrollToLoad='true'>

    <items>
        <ObjectListItem type='{device&gt;/listItemType}' 
                    press='onSelect' 
                    title='{Name}' 
                    number='{ path: "Price", formatter: "exp.ind.cli.util.Formatter.currencyValue" }' 
                    numberUnit='USD'>
        </ObjectListItem>
    </items>
</List>

I think it makes easier to spot the attributes and improve the readability of the xml file. Is there any way to achieve this?

Answer 1

This should almost work, it aligns the attributes slightly different than your example, but it's probably "close enough":

autocmd FileType xml let g:formatprg_args_expr_xml .= '." --indent-attributes 1"'

Which will format it like as:

<List id='list'
      items='{/sss}'
      mode='{device&gt;/listMode}'
      noDataText='{i18n&gt;masterListNoDataText}'
      select='onSelect'
      growing='true'
      growingScrollToLoad='true'>
    <items>
        <ObjectListItem type='{device&gt;/listItemType}'
                        press='onSelect'
                        title='{Name}'
                        number='{ path: "Price", formatter: "exp.ind.cli.util.Formatter.currencyValue" }'
                        numberUnit='USD'></ObjectListItem>
    </items>
</List>

Now, figuring this out was actually quite easy :-) Here's what I did:

1. I looked at the vim-autoformat homepage to see how it formatted XML files, and it says: "tidy for XHTML and XML".

2. So, we need to see if the tidy tool supports formatting the attributes like you want. After installing tidy, I ran tidy -h to see the help for this program. This told me that -help-config lists all configuration options, so I ran that:

   $ tidy -help-config
   

   This gave me a very long list, so I put the output in Vim:

   $ tidy -help-config | vim -
   

3. Since we want to do something with attributes, I used /attr to search for that, and after pressing n once I get:

   indent-attributes           Boolean    y/n, yes/no, t/f, true/false, 1/0
   

   I have no idea what this does, but it looks like it might be what we want?

4. Let's try adding this option. I went back to the vim-autoformat homepage, and noticed the "How can I change the behaviour of formatters, or add one myself?" section, which is how I figured out how to add the above option (this is the only part that required some effort, since the section isn't brilliantly written).

Answer 2

The suggested solution didn't work for me. formatprg_args_expr_xml is no longer recognized in the current version (at 713e7c2).

I solved the issue by adding these two lines in my .vimrc.

let g:formatdef_fmt_custom_xml = '"tidy -xml -q --show-errors 0 --show-warnings 0 --indent-attributes 1"'
let g:formatters_xml = ['fmt_custom_xml']

Of course I had to make sure tidy is already installed and present in my $PATH.