How to render view to file

I want to render a view to a file that gets stored on my hard disk.

I've created an app that allows me to automate e-learning content
generation. I perform basic data entry and select one of many HTML
content templates I've created. Rendering the template with the merged
data is no problem, but how can I then write the raw HTML to disk as a
file instead of rendering it as a view that the user sees in their
browser?

Thanks in advance,

Corey Murphy wrote:

I want to render a view to a file that gets stored on my hard disk.

I've created an app that allows me to automate e-learning content
generation. I perform basic data entry and select one of many HTML
content templates I've created. Rendering the template with the merged
data is no problem, but how can I then write the raw HTML to disk as a
file instead of rendering it as a view that the user sees in their
browser?

Thanks in advance,

I'm not sure about full templates, but this should work for partials

  content = render :partial => 'mypartial', :locals => { :foo => bar }
  File.open('path/to/file.html', 'r+') do |f|
    f.write content
  end

Alex Wayne wrote:

I'm not sure about full templates, but this should work for partials

  content = render :partial => 'mypartial', :locals => { :foo => bar }
  File.open('path/to/file.html', 'r+') do |f|
    f.write content
  end

Tried with no luck. Never got the file to write to disk. Rails
complained about some dynamic constant assignment error which I couldn't
figure out. When I render the page as a full template, it displays
without error, so why changing it to a partial and doing what you
suggested causes a problem I don't understand.

Corey Murphy wrote:

Alex Wayne wrote:

I'm not sure about full templates, but this should work for partials

  content = render :partial => 'mypartial', :locals => { :foo => bar }
  File.open('path/to/file.html', 'r+') do |f|
    f.write content
  end

Tried with no luck. Never got the file to write to disk. Rails
complained about some dynamic constant assignment error which I couldn't
figure out. When I render the page as a full template, it displays
without error, so why changing it to a partial and doing what you
suggested causes a problem I don't understand.

Because "render :partial" returns a string, right then and there. All
other types of rendering to my knowledge trigger the rendering engine to
send something to the browser.

Besides, I think there is an even easier way. Page caching. Page
caching essentially does what you are describing. Render a view, save
that result to a file.

Try, in your controller:

  caches_page :foo

  def foo
    @foo = Foo.find(params[:id])
    ...
  end

Now go to /my_controller/foo. Now look in public/my_controller/foo.html
and you should see what was just rendered. This is designed to caches
content as static files so Rails only has to dynamically generate this
stuff once. I dont know if that fits your use case or not, but it
should work.

Alex Wayne wrote:

Because "render :partial" returns a string, right then and there. All
other types of rendering to my knowledge trigger the rendering engine to
send something to the browser.

Besides, I think there is an even easier way. Page caching. Page
caching essentially does what you are describing. Render a view, save
that result to a file.

Try, in your controller:

  caches_page :foo

  def foo
    @foo = Foo.find(params[:id])
    ...
  end

Now go to /my_controller/foo. Now look in public/my_controller/foo.html
and you should see what was just rendered. This is designed to caches
content as static files so Rails only has to dynamically generate this
stuff once. I dont know if that fits your use case or not, but it
should work.

Ok, that worked, so I'm a little closer to my desired outcome. Only
problem I see is I need to be able to control where that content gets
stored and the filenames that are assigned to the cached pages. I
simply need greater control over those elements and I don't think this
method (after reading through the API) is going to allow me to do so. I
really appreciate your help thus far though as this has opened my eyes
to more rails functionality.

Corey Murphy wrote:

Ok, that worked, so I'm a little closer to my desired outcome. Only
problem I see is I need to be able to control where that content gets
stored and the filenames that are assigned to the cached pages. I
simply need greater control over those elements and I don't think this
method (after reading through the API) is going to allow me to do so. I
really appreciate your help thus far though as this has opened my eyes
to more rails functionality.

Maybe an after_filter?

  after_filter :write_file

  def foo
    @foo = Foo.find(params[:id])
    ...
  end

  protected
    def write_file
      File.open('path/to/file', 'r+') do |f|
        f.write response.body
      end
    end

Alex Wayne wrote:

Maybe an after_filter?

  after_filter :write_file

  def foo
    @foo = Foo.find(params[:id])
    ...
  end

  protected
    def write_file
      File.open('path/to/file', 'r+') do |f|
        f.write response.body
      end
    end

Went back to the original idea of rendering partial to variable and then
writing variable to file. Solved the problem related to the error I was
receiving thanks to Fred's post and I think I'm back on track.

Thanks for all the ideas and help,

So I've read everything I can find on file I/O and for some reason I'm
only able to write the contents of the partial to a file that already
exists. When I try to create a new file using either "File.new" or
"File.open" both return the same error of "No such file or directory . .
.". I've tried both below with no luck; same error. I've also tried
with an absolute path including drive letter, etc. since I'm only
running a localhost webbrick server at the moment with the same results.

content = render :partial => "foo"
File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "wb") do |f|
  f.write(content.read)
end

content = render :partial => "foo"
File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "r+") do |f|
  f.write(content)
end

So why is it if the file exists, I can write to it, but if it doesn't
exist, neither the create or open methods claim to be able to
create/find the file?

Corey Murphy wrote:

So I've read everything I can find on file I/O and for some reason I'm
only able to write the contents of the partial to a file that already
exists. When I try to create a new file using either "File.new" or
"File.open" both return the same error of "No such file or directory . .
.". I've tried both below with no luck; same error. I've also tried
with an absolute path including drive letter, etc. since I'm only
running a localhost webbrick server at the moment with the same results.

content = render :partial => "foo"
File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "wb") do |f|
  f.write(content.read)
end

content = render :partial => "foo"
File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "r+") do |f|
  f.write(content)
end

So why is it if the file exists, I can write to it, but if it doesn't
exist, neither the create or open methods claim to be able to
create/find the file?

I think that was my typo. I believe you want:

  File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "w+")

Note the "w+" not the "r+". That argument is the file mode. The r or w
stands for read or write, and I believe the "+" means create the file if
it does not exist. So "w+" means open a file for writitng, and create
it if it doesnt exist.

Note that the directory you put that file does need to be created
however.

Alex Wayne wrote:

I think that was my typo. I believe you want:

  File.open("#{RAILS_ROOT}/public/generatedHTML/#{id}.html", "w+")

Note the "w+" not the "r+". That argument is the file mode. The r or w
stands for read or write, and I believe the "+" means create the file if
it does not exist. So "w+" means open a file for writitng, and create
it if it doesnt exist.

Note that the directory you put that file does need to be created
however.

That did it. The "Programming Ruby" book does a horrible job of really
digging into File I/O. I was using the "r+" for reading and writing
under the assumption that using the "File.open..." syntax using a block
was the combined equivalent of File.new/open so I was expecting it to
create the file for me as well. The class/module definitions section of
the book provides the mode strings for I/O.

r+ = Read/Write, starts at beginning of file.
w+ = Read/Write, truncates existing file to zero length or creates a new
file for reading and writing.

Thanks a bunch once again!

Is there any way to bypass the double render checking? Now that I'm
able to get my content pages written to disk, I need to be able to write
a lot of pages to disk via a loop. I'm using the "render partial to
variable, write variable to file" approach. Unfortunately, the render
partial still renders the result to the browser and subsequent loops
through my recordset to write additional screens to disk is resulting in
the double render gotcha.

Any ideas? This kind stuff is easy to facilitate in ASP and other web
languages, but this is proving to be difficult with rails.

Could you just use render_to_string instead ?

Fred

Frederick Cheung wrote: