blocks|key|160966|text|标签存储在标签表中，您可以使用例如|type|unstyled|depth|inlineStyleRanges|entityRanges|data|160967|ActsAsTaggableOn::Tag.all|code-block|syntax|javascript|160968|如果您需要有关标签用法的更多信息，也可以查看该表|160969|ActsAsTaggableOn::Tagging|160970|，其中包含指向每个标记使用位置的链接，包括其上下文。|160971|要进一步将其应用于您的示例，您可以使用|160972|ActsAsTaggableOn::Tagging.includes(:tag).where(context:+'deshanatags').map+{+%7Ctagging%7C+{+'id'+=>+tagging.tag_id.to_s,+'name'+=>+tagging.tag.name+}+}.uniq|160973|让我们解释一下这条语句中的各个部分：|160974|包含‘|160975|’确保不同的标记是“立即加载”的，换句话说，不是加载n%2B1记录，而是只在数据库上执行两个查询|unordered-list-item|160976|
|160977|将记录限制为具有给定上下文的记录|160978|
‘|160979|’将生成的记录数组转换为一个新数组，其中包含您在问题中要求的散列，id映射到标记的id，名称映射到标记的名称|160980|160981|最后，'uniq‘确保您的列表中没有重复项|160982|
<代码>F212|160983|为了解决没有标记的标记的附加问题，您可以将where子句扩展为|160984|where("(context+=+'deshanatags')+AND+(tag_id+IS+NOT+NULL)")|160985|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1I|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1J|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1K|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1L|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1N|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1O|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|1P|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|Z|3|10|5|W|7|1R|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|1S|8|@]|9|@]|A|$]]|$1|13|3|14|5|W|7|1T|8|@]|9|@]|A|$]]|$1|15|3|Y|5|6|7|1U|8|@]|9|@]|A|$]]|$1|16|3|17|5|W|7|1V|8|@]|9|@]|A|$]]|$1|18|3|19|5|6|7|1W|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|6|7|1X|8|@]|9|@]|A|$]]|$1|1C|3|1D|5|D|7|1Y|8|@]|9|@]|A|$E|F]]|$1|1E|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]]|1F|$]]

The tags are stored in the Tags table, which you access from your program with e.g.

<pre><code>ActsAsTaggableOn::Tag.all
</code></pre>

If you need more info on tag usage, there is also the table

<pre><code>ActsAsTaggableOn::Tagging
</code></pre>

which contains links to where each tag is being used, including its context

To further apply this to your example, you can use

<pre><code>ActsAsTaggableOn::Tagging.includes(:tag).where(context: 'deshanatags').map { |tagging| { 'id' =&gt; tagging.tag_id.to_s, 'name' =&gt; tagging.tag.name } }.uniq
</code></pre>

Let's explain the various parts in this statement:

<ul>
<li>the 'includes' makes sure the different tags are "eager loaded", in other words, that instead of loading n+1 records, only 2 queries will be done on the database</li>
<li>the 'where' limits the records to the ones with the given context</li>
<li>the 'map' converts the resulting array of records into a new array, containing the hashes you asked for in your problem, with id mapped to the tag's id, and name mapped to the tag's name</li>
<li>finally the 'uniq' makes sure that you don't have doubles in your list </li>
</ul>

To also cope with your additional problem, being taggins without tag, you could extend the where clause to

<pre><code>where("(context = 'deshanatags') AND (tag_id IS NOT NULL)")
</code></pre>

blocks|key|158532|text|使用ActsAsTaggableOn::Tagging模型，您可以获得所有标签的列表，并根据上下文对其进行筛选，然后按如下方式格式化它们：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|158533|ActsAsTaggableOn::Tagging.all
.where(context:+"deshanatags")
.map+{%7Ctagging%7C+{+"id"+=>+"#{tagging.tag.id}",+"name"+=>+tagging.tag.name+}+}|code-block|syntax|javascript|158534|where将为我们提供给定上下文的所有标记的结果，然后我们使用map遍历该结果，检索结果中每个标记的相关标记，并获得id和name属性。|158535|如果您不使用ruby+1.9%2B，请确保直接链接这些方法(而不是跨几行|158536|然后，您可以对结果调用.to_json，以获得可以使用的格式正确的json对象|158537|编辑：|158538|我更新了post以阐明每个语句的作用，并更新了最终结果的格式以使用字符串作为键而不是符号|158539|entityMap^0|2|P|0|0|0|5|V|3|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|15|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|16|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|17|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|18|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|V|$]]

Using the <code>ActsAsTaggableOn::Tagging</code> model, you can get a list of all tags and filter them down according to context, then format them as follows:

<pre><code>ActsAsTaggableOn::Tagging.all
.where(context: "deshanatags")
.map {|tagging| { "id" =&gt; "#{tagging.tag.id}", "name" =&gt; tagging.tag.name } }
</code></pre>

The <code>where</code> will give us a result of all taggings for a given context, which we then iterate over using <code>map</code>, retrieving the related tag for each tagging in our result and getting the id and name attributes.

Make sure to chain the methods directly (not across several lines) if you're not using ruby 1.9+

You can then call .to_json on the result to get a properly formatted json object that you can use

<h2>edit:</h2>

I updated the post to clarify what each statement does and also updated the format of our final result to use strings as keys instead of symbols

blocks|key|158541|text|我个人认为，如果你有许多标签需要检索，那么这两种解决方案都会很慢，因为有很多单一的select语句。我会这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|158542|ActsAsTaggableOn::Tagging.includes(:tag).where(context:+'deshanatags').uniq.pluck(:id,+:name)|code-block|syntax|javascript|158543|如果你在ruby+1.9%2B上|158544|这样一来，你最终会得到：|158545|SELECT+DISTINCT+"taggings"."id",+name+FROM+"taggings"+LEFT+OUTER+JOIN+"tags"+ON+"tags"."id"+=+"taggings"."tag_id"+WHERE+"taggings"."context"+=+'deshanatags'|158546|快速简单的imo|158547|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|U|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I personally think that both solutions will be slow if you have many tags to retrieve as there are many single select statements.
I'd do it like this:

<pre><code>ActsAsTaggableOn::Tagging.includes(:tag).where(context: 'deshanatags').uniq.pluck(:id, :name)
</code></pre>

If you're on ruby 1.9+

This way you'll just end up with:

<pre><code>SELECT DISTINCT "taggings"."id", name FROM "taggings" LEFT OUTER JOIN "tags" ON "tags"."id" = "taggings"."tag_id" WHERE "taggings"."context" = 'deshanatags'
</code></pre>

Quick and easy imo

blocks|key|158587|text|在较新的版本中，您可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|158588|ActsAsTaggableOn::Tag.for_context(:deshanatags)|code-block|syntax|javascript|158589|我最终从谷歌来到这里，但后来在维基中找到了答案。|158590|从wiki|offset|length|158591|从code|158592|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/mbleigh/acts-as-taggable-on/wiki/Get-all-tags-by-context|1|https://github.com/mbleigh/acts-as-taggable-on/blob/master/lib/acts_as_taggable_on/tag.rb#L52^0|0|0|0|1|4|0|0|1|4|1|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|11|8|@]|9|@$K|12|L|13|1|14]]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@$K|16|L|17|1|18]]|A|$]]|$1|O|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]|W|$5|R|S|T|A|$U|X]]]]

In more recent versions, you can use:

<pre><code>ActsAsTaggableOn::Tag.for_context(:deshanatags)
</code></pre>

I ended up here from Google, but then found the answer in the wiki.

From the <a href="https://github.com/mbleigh/acts-as-taggable-on/wiki/Get-all-tags-by-context" rel="nofollow noreferrer">wiki</a>

From the <a href="https://github.com/mbleigh/acts-as-taggable-on/blob/master/lib/acts_as_taggable_on/tag.rb#L52" rel="nofollow noreferrer">code</a>

I have set the <code>acts-as-taggable-on</code> gem in my model like this :

<pre><code> acts_as_taggable_on :deshanatags
</code></pre>

It use the context <code>deshanatags</code>. Now I need to get a list of all the tags (not only the ones assigned for one item. I need everything) in this context in the following format :

<pre><code>[
 {"id":"856","name":"House"},
 {"id":"1035","name":"Desperate Housewives"}
]
</code></pre>

How can I do this?

I tried to follow many tutorials but hit dead ends because most of them are written for Rails 3. Rails for have some changes to the model like removal of attr_accessor which make it difficult for me to understand those tutorials. So please help.

Simply im trying to add Jquery Token input (<a href="http://loopj.com/jquery-tokeninput/">http://loopj.com/jquery-tokeninput/</a>) to my app

PS : Through Tagging table, is there a way to get a list of tags like the output of Tag.all by filtering the context?

How to get a list of all tags while using the gem 'acts-as-taggable-on' in Rails (not the counts)

数据库

我在模型中设置了acts-as-taggable-on gem，如下所示： acts_as_taggable_on :deshanatags它使用上下文deshanatags。现在我需要获取所有标签的列表(不仅仅是分配给一个项目的标签。我需要以下格式的所有内容)：[    {"id":"856","name":"Hou...

问如何在Rails中使用gem‘acts as-taggable-on’时获得所有标签的列表(而不是计数)
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