Design and Implementation of compleX Information Systems


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I encountered a very specific issue when trying to convert the geometries read from shapefiles to geojson, and for some reason this failed.

I had some very simple code to inspect the shapefiles and see what I should do with them. In that process I also wanted to convert the geometries to geojson (for test), as that is the actual goal for me.

So my code iterates over a folder of shape-files, and then just does an inspection of the first element. This should give me an idea of what all the files contain. The code looked like this

Dir[File.join(root_folder, '*.shp')].sort.each do |shapefile|
  puts shapefile do |file|
    puts "File contains #{file.num_records} records."
    record =
    puts "First record geometry WKT  : #{record.geometry.as_text}"
    puts "             coordinates   : #{record.geometry.coordinates}"
    puts "             geometry JSON : #{RGeo::GeoJSON.encode(record.geometry)}"
    puts "             Attributes    : #{record.attributes.inspect}"

I got the weirdest error when trying to run this code

 gems/rgeo-0.6.0/lib/rgeo/geos/zm_feature_methods.rb:305:in `block in each': no block given (yield) (LocalJumpError)

Apparently one of the shjapefiles contained a MultiLinestring with a z and m coordinate. All zero, so whyyyyy ? But still: rgeo should be able to handle that?

I tracked the code in rgeo and found the following culprit in Rgeo::Geos::ZMMultiLineStringMethods

Ooooops. Now how could i fix this? I am currently working on an ancient version of rails, and thus also rgeo. I could open an issue to fix it, but still I would not be able to update my own version (mostly because of the activerecord-postgis-adapter).

But, thankfully, we are using ruby and we can hotfix code (reopen the class and fix the bug!). So I added an initializer in config\initializers\fix_rgeo_bug.rb with the following code

module RGeo
  module Geos
    module ZMMultiLineStringMethods # :nodoc:

      # overwrite to fix!
      def coordinates
        puts "COOOORDINATES"
        coords = []
        each do |gm|
          coords << gm.coordinates


... and now my code is running smoothly!!

So awesome it is possible in ruby to reopen classes. And that rails has a well controlled loading system and an entry-point before execution to place my own initializers. I have used this a few times before, mainly to fix outdated gems without having to update them, or add very specific behaviour. It is the combination of having readable code, open source code, and then re-opening classes to add my own behaviour or fix bugs. I am still thankful/happy every day to be working in ruby on rails :clap: :clap: :clap:

I wonder if there are other programming languages or frameworks where this is possible?

Now open an issue on rgeo to address this bug :)

So, unfortunately we have to deploy our rails projects on servers which are managed by our clients, and so this means those are windows servers. Luckily this no longer is a big deal, but I develop on mac and mostly deploy on linux machines (which align). But a new deployment on windows almost always adds some surprises. So we deploy using ruby 2.4 and somewhere in our Gemfile we use eventmachine and on the most recent deployment I suddenly got this weird error:

Unable to load the EventMachine C extension; To use the pure-ruby reactor, require 'em/pure_ruby'

Not sure what they mean here: do I need to adapt the gem-code???? But luckily some googling quickly turned up a solution. Apparently the eventmachine gem is not updated correctly to use ruby 2.4 or 2.5 and the proposed solution is to do

gem uninstall eventmachine  
gem install eventmachine --platform=ruby

instead. This sounds great. In theory. But in practice? I have a bundle Gemfile and after every deploy/bundle I will have to uninstall the eventmachine-1.2.7-x64-mswin32 gem. I do have a script that I run on windows to deploy, and so I could easily add

gem uninstall -aIx eventmachine 
gem install eventmachine --platform=ruby

(the -aIx will remove all eventmachine instances and not care about dependencies)
but this feels a little counter-productive (wrong?) and it did not always seem to work reliably.

So I was looking for ways to describe in my Gemfile how to install the gem with the correct platform. Unfortunately platform has a different meaning inside a Gemfile, and the ruby platform is anything but windows.

But then I had an inspirational moment, why not install the gem from github, in the correct version?

So in my Gemfile I wrote

gem 'eventmachine', '1.2.7', git: '', tag: 'v1.2.7'

Installing the required version directly from git, which does work and does not break my deployment script/routine.

We encountered this strange error using WiceGrid: on some occasions when paginating to the second page, we actually lost the filtering, but not for all columns.

WiceGrid offers to define columns which are only rendered when creating html or exporting to csv. For us specifically, in some cases we want to show some pretty html when rendering html but just show the text when rendering/exporting to csv. For instance:

g.column name: 'Status', attribute: 'status', in_csv: false do |plan|
    render 'grid_status_label', plan_request: plan, history: true
  g.column name: 'Status', attribute: 'status', in_html: false

When rendering html, it will render a partial called grid_status_label, when rendering csv it will just show the status-text.

However, when defining the same column twice, this also has an effect on the filter. Either because we "exclude" one of definitions the column or because the column is defined twice, I am not sure. The easy way would be to know if we are rendering csv before defining the column so we don't define it twice at all and not confuse WiceGrid.

Luckily, we can ask the @grid if it is outputting csv. So if in your controller you write something like

@grid = initialize_grid(SomethingWithAStatus, ...)

in the view you can just ask @grid.output_csv? to know if we are currently exporting to csv instead of html.

So with that knowledge, in your view you can write

<%= grid(@grid) do |g|  
       [.. your other columns ..]            

       g.column name: 'Status', attribute: 'status', in_csv: false do |plan|
         render 'grid_status_label', plan_request: plan, history: true
       if @grid.output_csv?
         g.column name: 'Status', attribute: 'status', in_html: false
     end -%>

... and pagination while filtering on status will work!!

I really love(d) using WiceGrid but unfortunately it is no longer maintained actively. There is a somewhat active branch, but it only works for rails 5 and not entirely sure what the status is there. So this is at least a fix so we can keep using WiceGrid in our current projects for now.

Not quite sure how I would like to proceed with WiceGrid, because the code-base is really large and there are some things I do not really like (e.g. having to use erb, the dsl is sometimes a bit heavy, there is no test-coverage --there is a separate test-project but mmmm, the layout is pretty much fixed). But on the other hand it has proven extremely easy and robust and extensible (define your own column-filter and render types). I will probably try to fork or restart with something similar.

The on_the_spot gem allows inline editing of data. In general this is something I prefer over forms: I do not want to switch to a new page to edit something, I want to edit it where I see it (I understand there are some very good cases for the standard show/edit pages).

So a very long while ago I created a small gem to edit data inline. It relies on the jEditable javascript, which is still working.

But how do you style the dynamically injected form?

In my projects, I use the translation files as follows, e.g. in on_the_spot.en.yml I write :

    ok: <button class="btn btn-primary btn-sm">Ok</button>
    cancel: <button class="btn btn-default btn-sm">Cancel</button>
    tooltip: Click to edit
    access_not_allowed: Access not allowed

This will make sure the buttons are styled correctly. But if you try this, the input is too narrow, and everything is just squished together.

So add this little sprinkle of css to make everything look a little better:

.on_the_spot_editing {
  input, select {
    width: auto !important;
    height: 30px !important;

    margin-right: 5px !important;

    //display: block;

    padding: 6px 12px;
    font-size: 14px;
    line-height: 1.42857143;
    color: #555555;
    background-color: #fff;
    background-image: none;
    border: 1px solid #ccc;
    border-radius: 4px;

    -webkit-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075);
    box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075);
    -webkit-transition: border-color ease-in-out 0.15s, box-shadow ease-in-out 0.15s;
    -o-transition: border-color ease-in-out 0.15s, box-shadow ease-in-out 0.15s;
    transition: border-color ease-in-out 0.15s, box-shadow ease-in-out 0.15s;
  textarea {
    width: 80%;

  .btn {
    margin: 1px !important;

What inline editing solution are you using with rails?

I am currently contemplating to switch over to start using vue.js for javascript sprinkles like this.

If you started using FontAwesome-5 in a Turbolinks project, you will quickly notice the icons disappear after the first page reload. So how can we fix that? I did not immediately find a reference inside the FontAwesome documentation, but luckily google proved helpful and I found this issue

Inside the issue I found the fix which I applied and worked for me. I created a new file app/javascripts/fix_fontawesome_reload.js with the following content

document.addEventListener("turbolinks:before-render", function(event) {

which was then automatically included in application.js (because I have the require_tree line).


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