From [&#167;3.3.3 Subset Conditions of the Rails Guides][2]:

&gt; If you want to find records using the `IN` expression you can pass an
&gt; array to the conditions hash:
&gt; 
&gt; ```ruby
&gt; Customer.where(orders_count: [1,3,5])
&gt; ```
&gt; 
&gt; This code will generate SQL like this:
&gt; 
&gt; ```sql
&gt; SELECT * FROM customers WHERE
&gt; (customers.orders_count IN (1,3,5))
&gt; ```

You can also use the [arel][1] syntax:

    Client.where(Client.arel_table[:order_count].in([1,3,5]))

will generate the same SQL.


  [1]: https://www.rubydoc.info/gems/arel/Arel/Nodes/In
  [2]: https://guides.rubyonrails.org/active_record_querying.html#subset-conditions

Is there a kind of URLEncode in Groovy?

I can&#39;t find any String → String URL encoding utility.

Example: `dehydrogenase (NADP+)` → `dehydrogenase%20(NADP%2b)`

&lt;i&gt;(`+` instead of `%20` would also be acceptable, as [some][1] implementations do that)&lt;/i&gt;


  [1]: http://www.opinionatedgeek.com/dotnet/tools/urlencode/Encode.aspx

How to encode URL in Groovy?

    
When I echo var_dump($_variable), I get one long, wrapping line with all varable&#39;s and values like

    [&quot;kt_login_user&quot;]=&gt;  string(8) &quot;teacher1&quot; [&quot;kt_login_id&quot;]=&gt;  string(3) &quot;973&quot; [&quot;kt_campusID&quot;]=&gt;  string(4) &quot;9088&quot; [&quot;kt_positionID&quot;]=&gt;  string(1) &quot;5&quot; 
    

Is there a way I can make each value display on its own line for ease of reading? Something like this:
    
    [&quot;kt_login_user&quot;]=&gt;  string(8) &quot;teacher1&quot; 
    [&quot;kt_login_id&quot;]=&gt;  string(3) &quot;973&quot; 
    [&quot;kt_campusID&quot;]=&gt;  string(4) &quot;9088&quot; 
    [&quot;kt_positionID&quot;]=&gt;  string(1) &quot;5&quot;

Making PHP var_dump() values display one line per value

I was wondering if anyone knew how to do an &quot;IN&quot; clause in activerecord.  Unfortunately, the &quot;IN&quot; clause is pretty much un-googleable so I have to post here.  Basically I want to answer a question like this &quot;Give me all the college students that are in these dormitories where the dormitory id is in this array [id array]&quot;.  I know how to write the query given a single dormitory id, but I don&#39;t know how to do it given an array of ids.

Any help is greatly appreciated.  I&#39;m sure this is a repost of a question somewhere, so I&#39;ll delete this once an answer/better search term is found.

Ruby Activerecord IN clause

<p>I was wondering if anyone knew how to do an "IN" clause in activerecord.  Unfortunately, the "IN" clause is pretty much un-googleable so I have to post here.  Basically I want to answer a question like this "Give me all the college students that are in these dormitories where the dormitory id is in this array [id array]".  I know how to write the query given a single dormitory id, but I don't know how to do it given an array of ids.</p>
<p>Any help is greatly appreciated.  I'm sure this is a repost of a question somewhere, so I'll delete this once an answer/better search term is found.</p>


The [Ruby docs for `dup`][1] say:

&gt; In general, `clone` and `dup` may have different semantics in descendent classes. While `clone` is used to duplicate an object, including its internal state, `dup` typically uses the class of the descendent object to create the new instance.

But when I do some test I found they are actually the same:

    class Test
       attr_accessor :x
    end

    x = Test.new
    x.x = 7
    y = x.dup
    z = x.clone
    y.x =&gt; 7
    z.x =&gt; 7

So what are the differences between the two methods?

  [1]: http://www.ruby-doc.org/core-2.0/Object.html#method-i-dup

What&#39;s the difference between Ruby&#39;s dup and clone methods?

I am trying to install curb 0.8.0 on a Windows computer but I can not seem to get anywhere. I have been trying every website 3 pages deep on my Google search. Please, anyone have an idea of how I can get this single thing installed. I have downloaded curl and extracted it to C:\curl.  I have added it to my path and am running the command: 

    gem install curb -- --with-curl-lib=C:\curl\bin --with-curl-include=C:\curl\include

But it doesn&#39;t work. I keep getting the same error. Any suggestions?

Can&#39;t find libcurl or curl/curl.h (RuntimeError)

The best way I can describe what I&#39;m looking for is to show you the failed code I&#39;ve tried thus far:

    case car
      when [&#39;honda&#39;, &#39;acura&#39;].include?(car)
        # code
      when &#39;toyota&#39; || &#39;lexus&#39;
        # code
    end

I&#39;ve got about 4 or 5 different `when` situations that should be triggered by approximately 50 different possible values of `car`. Is there a way to do this with `case` blocks or should I try a massive `if` block?

Case statement with multiple values in each &#39;when&#39; block

When I run `bundle install` for my Rails 3 project on Centos 5.5 it fails with an error:

    Gem::RemoteFetcher::FetchError: SSL_connect returned=1 errno=0 state=SSLv3 
    read server certificate B: certificate verify failed 
    (https://bb-m.rubygems.org/gems/multi_json-1.3.2.gem)
    An error occured while installing multi_json (1.3.2), and Bundler cannot continue.
    Make sure that `gem install multi_json -v &#39;1.3.2&#39;` succeeds before bundling.

When I try to install the gem manually (by `gem install multi_json -v &#39;1.3.2&#39;`) it works. The same problem occurs with several other gems. I use RVM (1.12.3), ruby 1.9.2, bundler 1.1.3. 

How to fix it?

bundle install fails with SSL certificate verification error

What is the way in rails to structure sql query to only select certain columns from the database, I have some large data fields which I want to avoid loading from continuous periodic ajax calls. Reading unnecessarily is resource consuming and slow. 

    @itemlist = Item.find(:all, :conditions =&gt; { .... } ) #this select all columns 

I am looking for `SELECT name, address FROM users;` instead of `SELECT * FROM users;` 



Ruby rails - select only few columns from the data base

Imagine the following situation:

I have a `dog` model and a `house` model. A dog can belong to a house, and a house can have many dogs, so:

    Class Dog &lt;  ActiveRecord::Base
      belongs_to :house
    end

    Class House &lt; ActiveRecord::Base
      has_many :dogs
    end

Now, imagine that I also want to create dogs that don&#39;t have a house. They don&#39;t belong to house. Can I still use that relationship structure and simply don&#39;t inform a `:house_id` when creating it?

Is there a better practice?

Obs.: I used this analogy to simplify my problem, but my real situation is: I have a model a user can generate instances of it. He can also create collections of those instances, but he can leave an instance outside a collection.


Best practice about empty belongs_to association

I&#39;m a PHP developer learning the awesomness of Ruby on Rails, I&#39;m loving ActiveRecord and i noticed something really interesting, Which is how ActiveRecord methods detect the end of method chain to execute the query.

    @person = Person.where(name: &#39;Jason&#39;).where(age: 26)
    
    # In my humble imagination I&#39;d think that each where() executes a database query
    # But in reality, it doesn&#39;t until the last method in the chain

How does this sorcery work?

How does Rails ActiveRecord chain &quot;where&quot; clauses without multiple queries?

I was wondering in what order are callbacks and validations called when an ActiveRecord object is created.

Let’s say I have some custom validations &amp; callbacks like the following:

    validates :reference_code, :if =&gt; :reference_code, :on =&gt; :create
    before_create :assign_reference

which one will run first? The callback needs to happen first or else the validation may fail.

What is the order of ActiveRecord callbacks and validations?

I&#39;m trying to find all Users with an id greater than 200, but I&#39;m having some trouble with the specific syntax.

    User.where(:id &gt; 200) 

and 

    User.where(&quot;? &gt; 200&quot;, :id) 

have both failed.

Any suggestions?

Rails: Using greater than/less than with a where statement

Undefining a method in Ruby is pretty simple, I can just use `undef METHOD_NAME`.

Is there anything similar for a class? I am on `MRI 1.9.2`. 

I have to undefine an ActiveRecord Model, run two lines of code, and restore the model back to its original form.

The problem is, I have an model `Contact` and I am using a company&#39;s API and it happens that they have some class called `Contact`, and changing my model name would be lot of work for me. 

What can I do in this situation?

Content Type	Original Author	Original Content on Stackoverflow
Question	Black Dynamite	View Question on Stackoverflow
Solution 1 - Ruby	Chen Kinnrot	View Answer on Stackoverflow

Ruby Activerecord IN clause

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Making PHP var_dump() values display one line per value

How to encode URL in Groovy?

Attributions