As of now, I don’t remember now what my actual plans were to do. I just had one major thought, to make some application just as a way to refresh my memory of Flask. But I also wanted to learn something new, as I have not done anything new for time now. While trying to merge these together I came across, SPA or Single Page Applications. This idea somehow created a curiosity in me. The research that I started off because of this curiosity lead me to try out AngularJS. Particularly at this infant stage of me in Javascript world, I had no specific bias towards any frameworks. So I just planned to take up AngularJS.

Thus, I started to try out each attributes in Angular like ng-bind, and the list goes on; I have no plans to elaborate on these things now. One main thing that I oversaw was the format in which angluar takes in the expression to evaluate from an HTML page(view).

<div ng-bind="{{ some-variable }}"></div>

This should have some to my notice even before the problem had come, and me struggling to print some Hello World string on the web page. The problem with this particular syntax is actually a clash between the Jinja templating engine used by flask and the new AngularJS front-end that we have introduced. Both use the same syntax to for expression that that is to be dynamically evaluated inside the template page.

With some basic research I was able to find few solutions for this. I am just trying to compile all the reading that I had done at a single place for future reference:

  • Use ng-view to insert another web page content into the one rendered by flask
<div ng-view></div>

  • There is way to change the {{ }} operator in angular to someother string. This change can help both pieces of codes angular and jinja library to peacefully work together

    The below basically changes the config of the application to change its starting and ending templatng tags to something else

myModule.config(function($interpolateProvider) {
  $interpolateProvider.startSymbol('[[');
    $interpolateProvider.endSymbol(']]');
    });

Another major trouble that I had, was with ng-repeat. I was trying to insert a model inside each <li> </li>tags. \ Say the sample code is given below:

<!-- Something here -->
<ul>
    <li ng-repeat="k in dict-of-keys">
        <div class="modal fade" id="k-edit" role="dialog">
            <!-- Something else here -->
            <h4 class="modal-title">{{ dict-of-keys[k] }}</h4>
            <!-- Something else else here -->
        </div>
    </li>
</ul>

The above html code was my first try. However, I think or whatever I did was not able to one issue resolved. All the list and modals, everything was working fine but the issue was with the data content in everything. All the models inside the ng-repeat lists was same and also it was the content of the first list entry.

Actually a closer look at the above code was enough to solve the problem. The root cause is that the model div gets created with the content of the first iteration of ng-repeat and then this model/content gets propagated throughout rest of the list entries. i.e. Here we have to uniquely identify the model div for each <li> tag.

<!-- Something here -->
<ul>
    <li ng-repeat="k in dict-of-keys">
        <div class="modal fade" id="k-edit-{{ k }}" role="dialog">
            <!-- Something else here -->
            <h4 class="modal-title"></h4>
            <!-- Something else else here -->
        </div>
    </li>
</ul>

Changing the id attribute from id="k-edit" to id="k-edit-{{ k }}" will help us to uniquely map each model div with the list entry and thus the data in each iteration is correctly displayed. This is not a very big issue on an average maybe. But me as a starter in this front-end development, it was a good learning experience for me. I have also seen many people asking very similar kinds of questions in stack overflow and elsewhere. Thus, I am just a bit relieved to see that I am not a lone crusader here.

I’ll update it as and when I face anything new(perhaps old for some people out there :P).

On a side note, the issue with templating tags ie “{{ }}”, happened while I was typing this post as well. The Liquid templating engine which is used by Jekyll also had the same templating tag. All the “{{ }}” I had put in the text was first consider for templating, then I had them all escaped. Here is a post regarding it.

The raw-endraw can also be a solution. Refer here.