Can the optionsText be shown while saving the optionsValue in a dropdown menu?

Question

Can the optionsText be shown while saving the optionsValue in a dropdown menu?

Here is the code snippet I am currently working with:

var model = function() {
    this.nameSomething = ko.observable('');
    this.nameId = ko.observable(0);
};

var vm = (function() {
var myList = [{ id: 1, type: 'foo1'}, { id: 2, type: 'foo2' }, { id: 3, type: 'foo3' }],
    selectedModel = ko.observable(model);
    
    return {
        myList: myList,
        selectedModel: selectedModel
    };
}());

ko.applyBindings(vm);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div data-bind="with: selectedModel">
    <select data-bind="options: $root.myList,
                       optionsText: 'type',
                       optionsValue: 'type',
                       value: nameSomething"></select><br />
    Display this: <span data-bind="text: nameSomething"><br />
    Store this: <span data-bind="text: nameId"><br /> <!-- not displaying anything -->
    <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
</div>

Can I save the value of optionsValue in nameId and the text from optionsText in nameSomething when the option is loaded/changed?

I need to show the selected text in the UI while storing the corresponding value in the database.

Any assistance on this issue would be greatly appreciated. I am also open to any tips for beginners using Knockout JS.

UPDATE

Added a working example

javascript knockout.js

Answer 1

Answer №1

One way to solve this is by utilizing the entire object as the "selected value". This approach allows for a clear separation between what is displayed and what is stored.

var defaultItem =  {
    id: 1,
    type: 'foo1',
};

var vm = (function() {
var myList = [{ id: 1, type: 'foo1'}, { id: 2, type: 'foo2' }, { id: 3, type: 'foo3' }],
    selectedModel = ko.observable(defaultItem);
    
    return {
        myList: myList,
        selectedModel: selectedModel
    };
}());

ko.applyBindings(vm);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div>
    <select data-bind="options: myList,
                       optionsText: 'type',
                       value: selectedModel"></select><br />
    <div data-bind="with: selectedModel">
        <span>Display this: </span><span data-bind="text: type"></span><br />
        <span>Store this: </span><span data-bind="text: id"></span><br />
        <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
    </div>
</div>

Answer 2

One way to solve this is by utilizing the entire object as the "selected value". This approach allows for a clear separation between what is displayed and what is stored.

var defaultItem =  {
    id: 1,
    type: 'foo1',
};

var vm = (function() {
var myList = [{ id: 1, type: 'foo1'}, { id: 2, type: 'foo2' }, { id: 3, type: 'foo3' }],
    selectedModel = ko.observable(defaultItem);
    
    return {
        myList: myList,
        selectedModel: selectedModel
    };
}());

ko.applyBindings(vm);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div>
    <select data-bind="options: myList,
                       optionsText: 'type',
                       value: selectedModel"></select><br />
    <div data-bind="with: selectedModel">
        <span>Display this: </span><span data-bind="text: type"></span><br />
        <span>Store this: </span><span data-bind="text: id"></span><br />
        <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
    </div>
</div>

Answer 3

Answer №2

If you choose not to identify the optionsValue, the selected value will be set to the full object and you can customize it as you wish... You will have access to all properties (if I understood your question correctly).

<div data-bind="with: selectedModel">
    <select data-bind="options: $root.myList,
                       optionsText: 'type',
                       value: nameSomething"></select><br />
        Display this: <span data-bind="text: nameSomething().id"><br />
    Store this: <span data-bind="text: nameSomething().nameId"><br /> <!-- not displaying anything -->
    <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
</div>

Take a look at my fiddle here http://jsfiddle.net/bgap47d4/2/

Answer 4

If you choose not to identify the optionsValue, the selected value will be set to the full object and you can customize it as you wish... You will have access to all properties (if I understood your question correctly).

<div data-bind="with: selectedModel">
    <select data-bind="options: $root.myList,
                       optionsText: 'type',
                       value: nameSomething"></select><br />
        Display this: <span data-bind="text: nameSomething().id"><br />
    Store this: <span data-bind="text: nameSomething().nameId"><br /> <!-- not displaying anything -->
    <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
</div>

Take a look at my fiddle here http://jsfiddle.net/bgap47d4/2/

Answer 5

Answer №3

It is not achievable directly. There are a few methods you can consider:

Utilizing a computed function (such as pureComputed) to retrieve the value by key from the array
Creating an observable and subscribing a function to the nameId that updates the observable

You have the option to use the selectedOptions binding and either subscribe to or fetch the currently selected option's value from the bound observableArray, but this serves as an alternative.

This solution provides guidance for your issue, demonstrating the structure that should be implemented in your viewmodel using the first method.

var viewModel = (function() {
  
  var list = ko.observableArray(
    [{ id: 1, type: 'foo1'}, 
     { id: 2, type: 'foo2' }, 
     { id: 3, type: 'foo3' }]
  );
  
  var selectedId = ko.observable();
  
  var selectedType = ko.pureComputed(function() {
    return list().find(function(item) { return item.id === selectedId(); }).type;
  });
  
  return {
    list: list,
    selectedId: selectedId,
    selectedType: selectedType
  };
  
})();

ko.applyBindings(viewModel);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div>
    <select data-bind="options: list,
                       optionsText: 'type',
                       optionsValue: 'id',
                       value: selectedId"></select><br />
    Display this: <span data-bind="text: selectedType"></span><br />
    Store this: <span data-bind="text: selectedId"></span><br /> <!-- not displaying anything -->
    <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
</div>

Answer 6

It is not achievable directly. There are a few methods you can consider:

Utilizing a computed function (such as pureComputed) to retrieve the value by key from the array
Creating an observable and subscribing a function to the nameId that updates the observable

You have the option to use the selectedOptions binding and either subscribe to or fetch the currently selected option's value from the bound observableArray, but this serves as an alternative.

This solution provides guidance for your issue, demonstrating the structure that should be implemented in your viewmodel using the first method.

var viewModel = (function() {
  
  var list = ko.observableArray(
    [{ id: 1, type: 'foo1'}, 
     { id: 2, type: 'foo2' }, 
     { id: 3, type: 'foo3' }]
  );
  
  var selectedId = ko.observable();
  
  var selectedType = ko.pureComputed(function() {
    return list().find(function(item) { return item.id === selectedId(); }).type;
  });
  
  return {
    list: list,
    selectedId: selectedId,
    selectedType: selectedType
  };
  
})();

ko.applyBindings(viewModel);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div>
    <select data-bind="options: list,
                       optionsText: 'type',
                       optionsValue: 'id',
                       value: selectedId"></select><br />
    Display this: <span data-bind="text: selectedType"></span><br />
    Store this: <span data-bind="text: selectedId"></span><br /> <!-- not displaying anything -->
    <pre data-bind="text: ko.toJSON($root.selectedModel, null, 2)"></pre>
</div>

Can the optionsText be shown while saving the optionsValue in a dropdown menu?

Answer №1

Answer №2

Answer №3

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