AngularJS binding to nested model properties

Question

We've built a dynamic form directive that gets metadata from the server and then builds a form dynamically. The rendered inputs are bound to a Model object separate from the metadata. In order to achieve that, we are doing something like this:

<input type="field.Type" 
       ng-model="Model[field.Name]" 
       ng-repeat="field in metadata.Fields" />

Assume that the above mark-up works (well, it does - in a simple scenario) and the binding works as expected. Unfortunately, it all breaks when the model we're using is not a collection of scalar properties. Examples include:

Measure.Id
Dimensions[0].SelectedAttribute

As you can see, the problem occurs when I have a nested property and/or when I have a list that I need to bind to, which is obviously a normal behavior because we're using the Model[propertyName] notation to achieve the dynamic binding.

I've thought about parsing the expression coming from the server myself and walk-down the hierarchy of the model (the nested properties) and figure out the binding, but I couldn't get it right (yet). Moreover, I still have nothing in mind of hour I'm going to solve the list/array binding issue.

Any thoughts?

Community · Accepted Answer · 2017-05-23 12:11:08Z

2

I'm not quite sure if your trying to get a list property from the model or if you're trying to create a Dynamic Set Model?

As for the list property that isn't very difficult just append an array to the model or even append some object with a list property.

Multiple Models

Or are you looking to use multiple 'models'?

function MyCtrl($scope, $filter) 
{        
    $scope.Model = { 
        SubModel : {
             // Submodel stuff
        },

        FooModel : {
             // Submodel stuff
        }
    }
}

EDIT:

I completely missed the point of the question my first try. The question really wanted to render different content based on a property's type (if that's not what you wanted I apologize) Plunker Example

HTML

<div ng-app ng-controller="MyCtrl">
  <div ng-if="Configuration.hasLevels">
    <div ng-repeat="lvl in Configuration.levels">
      <input type="textbox" value="{{lvl.severity}}">
      {{lvl.name}}
    </div>
  </div>
  <div ng-if="!Configuration.hasLevels">
    no levels: {{Configuration.levels}}
  </div>
</div>

JavaScript

function MyCtrl($scope, $filter) 
{
  // Configuration Object
  $scope.Configuration = {
    debug : true,
    // Log Levels
    levels : [
      new Level("log", 0),
      new Level("warning", 1),
      new Level("error", 2)
    ]
    // levels : "hello world"
  };

  $scope.Configuration.hasLevels = ($scope.Configuration.levels instanceof Array);
}

function Level(name, severity) { this.name = name; this.severity = severity; }

edited May 23, 2017 at 12:11

CommunityBot

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answered Sep 12, 2013 at 14:47

Nate-Wilkins

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2 Comments

Kassem Over a year ago

Apparently, you did not get the point of my question. In the data coming from the server, I do not know whether a property is a list or not, all I know it is a property (on the client side - in the HTML to be more specific). The nested models inside the main model is another issue which I also need to resolve. So in brief, I need a way to pass the binding expression of the ng-model properly to cater for all mentioned scenarios.

Nate-Wilkins Over a year ago

@Kassem Fixed I believe that's what you want the only problem I see in this is that you said that the client is the one who knows which property. I'd change this a bit to create the <div ng-if=...

Kassem · Accepted Answer · 2013-09-17 06:05:50Z

So I ended up having to create the HTML in the JavaScript code instead of using an HTML template... Something like that:

FormBuilder.prototype.getAtomField = function (field) {
    var self = this;
    var atom = '<atom type="field.Type" name="field.Title" data-ng-show="field.Visible || evaluateExpression(field.VisibleIf)" hidevalidation="field.HideValidation" withlabel="field.WithLabel"'
     + 'datavalue="' + self.getDataValueBindingExpression(field.Name) + '" class="field.ClassName" required="field.Required || evaluateExpression(field.RequiredIf)"'
     + 'enabled="(field.Enabled || evaluateExpression(field.EnabledIf))" watermark="field.Watermark" orientation="field.Orientation" example="field.Example" modelkey="api.getFieldModelKey(field.Name)"'
     + 'min="field.Min" max="field.Max" description="field.Description" suggestedvalues="field.SuggestedValues" limittosuggestions="field.LimitToSuggestions" multiple="field.Multiple"'
     + 'displaypath="field.DisplayPath" valuepath="field.ValuePath" remoteurl="field.RemoteUrl" changehandler="invokeAction" changehandlerparam="field.ChangeHandler"'
     + 'source="field.Source" sourcefilter="field.SourceFilter" groupnamepath="field.GroupNamePath" disabledpath="field.DisabledPath" iconpath="field.IconPath"'
     + 'toggle="field.Toggle" formatresult="field.FormatResult" formatselection="field.FormatSelection" requestdatamapper="field.RequestDataMapper"'
     + 'responsedatamapper="field.ResponseDataMapper" pagelimit="field.PageLimit" remotedatatype="field.RemoteDataType" eagersearch="field.EagerSearch"'
     + 'numberofdigits="field.NumberOfDigits" step="field.Step" format="api.evaluateRegexExpression(field.Format, field.Type)"></atom>';
    return atom;
};

Note that atom is just a wrapper directive that is kind of equivalent to a form field. The part doing the trick here is the call to self.getDataValueBindingExpression(field.Name) which simply returns the concatenated field name properly:

FormBuilder.prototype.getDataValueBindingExpression = function (name) {
    var self = this;
    return 'api.description.Model.' + name;
};

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