1

What we are trying to do is to store a chunk of erb code in a string and then render the code in run time in erb.

Here is the chunk of erb code which is stored as string:

<tr>
      <th>#</th>
      <th><%= t('Date') %></th>
      <th><%= t('Project Name') %></th>
      <th><%= t('Task Name') %></th>
      <th><%= t('Log') %></th>
      <th><%= t('Entered By') %></th>

    </tr>

    <% @logs.each do |r| %>
        <tr>
          <td><%= r.id %></td>
          <td><%= (r.created_at + 8.hours).strftime("%Y/%m/%d")%></td>
          <td><%= prt(r, 'task.project.name') %></td>
          <td><%= prt(r, 'task.task_template.task_definition.name') %></td>
          <td><%= prt(r, :log) %></td>
          <td><%= prt(r, 'last_updated_by.name') %></td>

        </tr>
    <% end %>

t() is the translation method for internationalization.

How can we insert the above erb code stored in string back to erb file below for rendering (in pseud code) ?

  <table class="table table-striped">
    <% erb_code = retrieve(chunk_of_erb_code)%>
    <% erb_code here for rendering %>

  </table>

Is there a solution for the problem? Thanks for help.

UPDATE:

Working code with render inline (by kamesh):

<% erb_code = find_config_const('task_log_view', 'projectx')%>
<%= render inline: ERB.new(erb_code).result(binding) %>

For a good practice, variable erb_code could be moved into the controller.

Improve this question

4 Answers 4

Reset to default
4

I think i got your question. you can append any html string in erb using in view:

<%= render inline:"<p>new Field</p>"%>

or

<%= render inline: "<% products.each do |p| %><p><%= p.name %></p><% end %>" %>

or in controller as:

render inline: "<% products.each do |p| %><p><%= p.name %></p><% end %>"

writing it in any _xyz.html.erb or xyz.html.erb and also can be used from controller, as well. for more check following link. in sub topic - 2.2.6 Using render with :inline. rails guide

I have checked working of this. Let me know in case of any issue.

Improve this answer
Sign up to request clarification or add additional context in comments.

2 Comments

Yep, this works for me: <%= render inline: get_erb %>. The method get_erb is called and the returned string is substituted into the erb file before erb executes all the ruby code in the file
Works great! Here is the working code: <% code = find_config_const('task_log_view', 'projectx')%> <%= render inline: ERB.new(code).result(binding) %> variable code could be moved to controller.
1

You definitely want to do it with partials or helpers, because the solution you are requesting for is complicated and confusing.

But if you really need to implement this solution, you would have to create a .html.erb.erb file, it would be interpreted by erb twice.

Given the following helpers

def print_one
  "1"
end

def print_a_method
  "<%= print_one %>"
end

Pass 1, RoR interpret the html.erb.erb file, which originally look like this:

<%= "<%=" %> print_one.to_i + print_one.to_i <%= "%>" %>

<%= print_a_method %>

<%= 5 + 3 %>

The trick in first line is to "generate the erb tags for the second pass": <%= "<%=" %> and <%= "%>" %> that will become <%= and %>, and the rest of the first line is not interpreted during pass 1.

On the other hand the second line will be entirely interpreted during this pass, and the output of print_a_method will be placed in the file for it to be interpreted during the second pass.

The third line is interpreted as well and output its result.

Pass 2, RoR takes the result of the first pass which is now a .html.erb file. Internally it would look like this

# As you can seem the erb tags was generated, and now the erb code is ready for pass 2
<%= print_one.to_i + print_one.to_i %>

# The second line was interpreted and its result is erb code that will be interpreted during pass 2
<%= print_one %>

# the third line was interpreted and give the following output
8

Final render would be the .html file where the file from pass 2 is interpreted and that would look like this

2

1

8
Improve this answer

2 Comments

A html.erb file has been created under views. When the html.erb is called at run time, the erb file retrieves erb code from database and render the html.erb plus the retrieved erb string all together. The retrieving makes the rendering dynamical.
Yes. the erb code retrieved from your database would be done in my example by the method print_a_method, and you have to use a .html.erb.erb file, it complicated but if you really need to proceed like this then you can follow my guideline
1

Seems like a job for partials.

# app/views/some_folder/_my_erb_partial 
<%= t(whatever) %>

...

<table class="table table-striped">
  <%= render 'some_folder/my_erb_partial' %>
</table>

Update.

If you need to store ERB templates in your database and render them in real time, take a look at render erb from database into view problem please help!

However, I don't know if this is necessarily your best option, as it could lead to security issues and other issues (namely, if you change code, your templates stored in the database would likely break). In most cases, it would be best just to make a new model for whatever you need to do, and do it the Rails way (with partials).

Improve this answer

5 Comments

Need dynamically form the erb file for rendering.
Well, actually, that's what a partial does. Are you saying that you need to store erb templates in the database and then present them?
The erb code is stored in a variable after retrieving from db. If using partial, how does partial render from a string variable?
You would make a model called Project (or whatever), and then give it variables (date, entered_by, etc) and then load them into your partial accordingly. For example, <%= t(@project.date)%>
I took a existing erb file as an example. The html.erb file renders fine.
1

(I was able to simplify my original answer quite a bit.)

You can create application helpers like this:

helpers/application_helper.rb:

module ApplicationHelper

  def my_erb_converter(template)
    erb = ERB.new(template)
    erb.result
  end

  def t(str)
    "***#{str}***"
  end

end

Then in an action do:

include ApplicationHelper

class SomeController < ApplicationController
  ...
  ...
  def some_action
    @html = my_erb_converter("<div><%= t('hello') %></div>")
    ...
  end

Then in your view:

<table class="table table-striped">
    <%= raw @html %>
</table>

This also works for me:

module ApplicationHelper

  def convert_erb(template)
    erb = ERB.new(template)
    erb.result
  end

  def t(str)
    "***#{str}***"
  end

  def get_erb
    "<div><%= t('hello') %></div>"
  end
end

View:

<table class="table table-striped">
    <%= raw convert_erb(get_erb) %>
</table>
Improve this answer

2 Comments

Here is the code in html.erb and it renders nothing on screen: <% code = find_config_const('task_log_view', 'projectx')%> <% ERB.new(code).result(binding) %>
<% %> tags never insert anything in a page. This works for me: <% code = get_erb %> <div><%= raw ERB.new(code).result %></div>. I put require 'erb' in environments/development.rb.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.