权限没有,则隐藏 function forum_list_access_filter($forumlist, $gid, $allow = 'allowread') { global $grouplist; if (empty($forumlist)) return array(); if (1 == $gid) return $forumlist; $forumlist_filter = $forumlist; $group = $grouplist[$gid]; foreach ($forumlist_filter as $fid => $forum) { if (empty($forum['accesson']) && empty($group[$allow]) || !empty($forum['accesson']) && empty($forum['accesslist'][$gid][$allow])) { unset($forumlist_filter[$fid]); } unset($forumlist_filter[$fid]['accesslist']); } return $forumlist_filter; } function forum_filter_moduid($moduids) { $moduids = trim($moduids); if (empty($moduids)) return ''; $arr = explode(',', $moduids); $r = array(); foreach ($arr as $_uid) { $_uid = intval($_uid); $_user = user_read($_uid); if (empty($_user)) continue; if ($_user['gid'] > 4) continue; $r[] = $_uid; } return implode(',', $r); } function forum_safe_info($forum) { //unset($forum['moduids']); return $forum; } function forum_filter($forumlist) { foreach ($forumlist as &$val) { unset($val['brief'], $val['announcement'], $val['seo_title'], $val['seo_keywords'], $val['create_date_fmt'], $val['icon_url'], $val['modlist']); } return $forumlist; } function forum_format_url($forum) { global $conf; if (0 == $forum['category']) { // 列表URL $url = url('list-' . $forum['fid'], '', FALSE); } elseif (1 == $forum['category']) { // 频道 $url = url('category-' . $forum['fid'], '', FALSE); } elseif (2 == $forum['category']) { // 单页 $url = url('read-' . trim($forum['brief']), '', FALSE); } if ($conf['url_rewrite_on'] > 1 && $forum['well_alias']) { if (0 == $forum['category'] || 1 == $forum['category']) { $url = url($forum['well_alias'], '', FALSE); } elseif (2 == $forum['category']) { // 单页 $url = ($forum['threads'] && $forum['brief']) ? url($forum['well_alias'] . '-' . trim($forum['brief']), '', FALSE) : url($forum['well_alias'], '', FALSE); } } return $url; } function well_forum_alias() { $forumlist = forum_list_cache(); if (empty($forumlist)) return ''; $key = 'forum-alias'; static $cache = array(); if (isset($cache[$key])) return $cache[$key]; $cache[$key] = array(); foreach ($forumlist as $val) { if ($val['well_alias']) $cache[$key][$val['fid']] = $val['well_alias']; } return array_flip($cache[$key]); } function well_forum_alias_cache() { global $conf; $key = 'forum-alias-cache'; static $cache = array(); // 用静态变量只能在当前 request 生命周期缓存,跨进程需要再加一层缓存:redis/memcached/xcache/apc if (isset($cache[$key])) return $cache[$key]; if ('mysql' == $conf['cache']['type']) { $arr = well_forum_alias(); } else { $arr = cache_get($key); if (NULL === $arr) { $arr = well_forum_alias(); !empty($arr) AND cache_set($key, $arr); } } $cache[$key] = empty($arr) ? '' : $arr; return $cache[$key]; } ?>javascript - Correct way to handle v-if with v-for in Vue - Stack Overflow
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javascript - Correct way to handle v-if with v-for in Vue - Stack Overflow

programmeradmin9浏览0评论

How should we handle a v-for bined with a v-if in this exemple:

Here my data.json:

[
  {
    image: 'foo.jpg'
  },
  {
    image: 'foobar.jpg',
    video: 'bar.mp4'
  },
  {
    image: 'barfoo.jpg'
  }
]

In my vue template, I'd like to render something like this:

<div v-for="(item, key, index) in data" : key="index">
   <img :src="item.image">
   <video v-if="!!item.video" :src="item.video"></video>
</div >

But as the documentation say, we should avoid v-if with v-for and instead use a puted value. But there I need to render the image even if the json entry doesn't have a video.

That's not a big deal, I've find a solution but I'd like to know the best way to handle this.

How should we handle a v-for bined with a v-if in this exemple:

Here my data.json:

[
  {
    image: 'foo.jpg'
  },
  {
    image: 'foobar.jpg',
    video: 'bar.mp4'
  },
  {
    image: 'barfoo.jpg'
  }
]

In my vue template, I'd like to render something like this:

<div v-for="(item, key, index) in data" : key="index">
   <img :src="item.image">
   <video v-if="!!item.video" :src="item.video"></video>
</div >

But as the documentation say, we should avoid v-if with v-for and instead use a puted value. But there I need to render the image even if the json entry doesn't have a video.

That's not a big deal, I've find a solution but I'd like to know the best way to handle this.

Share Improve this question edited Jul 14, 2022 at 1:41 tony19 139k23 gold badges277 silver badges347 bronze badges asked Feb 4, 2019 at 14:46 Allan RaquinAllan Raquin 6138 silver badges26 bronze badges
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1 Answer 1

Reset to default 7

I think that you are misunderstanding the documentation. In this instance, it makes sense to use both v-for and v-if because you are always going to render at least the <img> and you might render the <video>. The documentation is trying to show that you should pre-filter a list of items if the v-if and v-for are on the exact same element.

The example the docs are showing are trying to get you to cut a list that would show only only 2 of the 3 total elements down to just 2 elements and letting the puted prop tell you when there are more. Otherwise you have to iterate through the entire list every time you need to re-render.

Consider this difference:

// An array of 1000 items but only 1 has a video element
const data = [0...999];

data.push({
  image: "some.jpg",
  video: "some.mp4"
});
<!--
We always render 1000 items but only some will have video 
-->
<div 
v-for="(item, key, index) in data" 
:key="index">
  <img :src="item.image">
  <video v-if="!!item.video" :src="item.video"></video>
</div>


<!-- 
We have to visit 1000 elements but 
only 1 will actually end up rendering
-->
<div 
v-if="!!item.video" 
v-for="(item, key, index) in data" 
:key="index">
  <img :src="item.image">
  <video :src="item.video"></video>
</div>
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