Tag: asp.net mvc

Model Binding an Array from a Form Post | Asp.Net MVC & Asp.Net Core

if you form post html form fields:

<li>
  <label for="name">Your name<span>*</span></label>
  <input type="text" id="name" name="Name" />
</li>
<li>
  <label for="phoneNumber">Telephone<span>*</span></label>
  <input type="tel" id="phoneNumber" name="PhoneNumber" />
</li>

to a Controller using the [FromForm] attribute, AspNet will modelbind the form fields to your parameters by matching the name= attribute of the input elements to Property names on the parameter class:

class MyController : Controller
{
    public IActionResult Index([FromForm]Contact contact){ ... }
}

// ----
public class Contact
{
    public string Name {get;set;}
    public string PhoneNumber {get;set;}
}

But what about model binding an array — for instance, if you have a list of question inputs, and want to store the answers in a list?

If you name each field as if it were an array element:

 <fieldset id="q1">
     <label class="question">Question 1</label>
     <ul class="form-style">
        <li>
            <input type="radio" id="c1" name="answers[0]" value="@c1"/>
            <label for="c1">@c1</label>
        </li>
        <li>
            <input type="radio" id="c2" name="answers[0]" value="@c2"/>
            <label for="c2">@c2</label>
        </li>
    </ul>
  </fieldset>
    <fieldset id="q2">
        <label class="question">Question 1?</label>
        <ul class="form-style">
            <li>
                <input type="radio" id="b1" name="answers[1]" value="@b1"/>
                <label for="b1">@b1</label>
            </li>
            <li>
                <input type="radio" id="b2" name="answers[1]" value="@b2"/>
                <label for="b2">@b2</label>
            </li>
            <li>
                <input type="radio" id="b3" name="answers[1]" value="@b3"/>
                <label for="b3">@b3</label>
            </li>
            <li>
                <input type="radio" id="b4" name="answers[1]" value="@b4"/>
                <label for="b4">@b4</label>
            </li>
        </ul>
    </fieldset>

then AspNet will bind the submitted fields named answers[0], answers[1], ... to an array Property in your class with the matching name:

public class Questions
{
    public string[] Answers {get;set;}
}

Dev Azure Pipeline Web Config Transform

The web.config transform appears at first glance to be somewhat orphaned in Azure DevOps. If you are deploying to a WebApp then the pipeline wizard will probably have given you this snippet for your Build step:

- task: VSBuild@1
  inputs:
    solution: '$(solution)'
    msbuildArgs: '/p:DeployOnBuild=true /p:WebPublishMethod=Package /p:PackageAsSingleFile=true /p:SkipInvalidConfigurations=true /p:DesktopBuildPackageLocation="$(build.artifactStagingDirectory)\WebApp.zip" /p:DeployIisAppPath="Default Web Site"'
    platform: '$(buildPlatform)'
    configuration: '$(buildConfiguration)'

To run config transforms you can add the additional parameter /p:TransformConfigFile=true to your msbuildArgs.

The replacement, of course, is the independent FileTransform task (which can also work within zip files). But once your site is packaged the Web.Release.Config is left behind; so you have to run the FileTransform task before, not after, the build step. (Similarly the WebAppDeployment task can't transform a Web.Release.config that isn't inside the package).

Slightly magically, the default parameter for the FileTransform is exactly what you typically want for web.Release.config transforms:

#xmlTransformationRules: '-transform **\*.Release.config -xml **\*.config-transform **\*.$(Release.EnvironmentName).config -xml **\*.config' # Optional

FileTransform can also do variable substitution, and you can have multiple FileTransform steps in your pipeline. I also like to see some diagnostic feedback so I include script step to show the xml transform result. But I put it before variable substitution, because the variables often include secrets:

- task: FileTransform@1
  displayName: Transform Release.Config
  inputs:
    folderPath: '$(System.DefaultWorkingDirectory)/Ui/'
    enableXmlTransform: true
    xmlTransformationRules: -transform **/*.Release.config -xml **/*.config

- task: PowerShell@2
  displayName: "Confirm web.config transform"
  inputs:
    targetType: 'inline'
    script: 'cat $env:System_DefaultWorkingDirectory/Ui/web.config'
    errorActionPreference: 'continue'

- task: FileTransform@1
  displayName: Variable substitution *.config
  inputs:
    folderPath: '$(System.DefaultWorkingDirectory)/Ui/'
    fileType: 'xml'
    targetFiles: '**/*.config'

- task: VSBuild@1
  ...etc..

Reference

An Asp.Net MVC HtmlHelper.RadioButtonsFor helper

These overloads will do the hopefully-obvious thing with a Model => Model.Property and a List of SelectListItems (or a single SelectListItem)

Use the RadioButtonLabelLayout setting to control whether you nest the radio button inside its label, or lay them out as siblings; and whether you like text before button or vice versa.

    public static class HtmlHelperRadioButtonExtensions
    {
        /// <summary>
        /// Returns radio buttons for the property in the object represented by the specified expression.
        /// A radio button is rendered for each item in <paramref name="listOfValues"/>.
        /// Use <paramref name="labelLayout"/> to control whether each label contains its button, or is a sibling, 
        /// and whether button precedes text or vice versa.
        /// <list type="bullet">
        /// <item>
        ///     <term>Example result for the default labelLayout= RadioButtonLabelLayout.LabelTagContainsButtonThenText:</term>
        ///     <description>
        ///     &lt;label for="Object_Property_Red"&gt;&lt;input id="Object_Property_Red" name="Object.Property" type="radio" value="Red" /&gt; Red&lt;/label&gt; 
        ///     &lt;label for="Object_Property_Blue"&gt;&lt;input id="Object_Property_Blue" name="Object.Property" type="radio" value="Blue" /&gt; Blue&lt;/label&gt; 
        ///     </description>
        /// </item>
        /// <item>
        ///     <term>Example result for labelLayout= RadioButtonLabelLayout.SiblingBeforeButton:</term>
        ///     <description>
        ///     &lt;label for="Object_Property_Red"&gt;Red&lt;/label&gt; &lt;input id="Object_Property_Red" name="Object.Property" type="radio" value="Red" /&gt;
        ///     &lt;label for="Object_Property_Blue"&gt; Blue&lt;/label&gt; &lt;input id="Object_Property_Blue" name="Object.Property" type="radio" value="Blue" /&gt;
        ///     </description>
        /// </item>
        /// </list>
        /// </summary>
        /// <param name="listOfValues">Used to generate the Value and the Label Text for each radio button</param>
        /// <param name="labelLayout">One <see cref="RadioButtonLabelLayout"/> to control the layout of the rendered button and its label.</param>
        /// <returns>
        /// An MvcHtmlString for the required buttons 
        /// 
        /// </returns>
        public static MvcHtmlString 
            RadioButtonsFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper,
                                                    Expression<Func<TModel, TProperty>> expression,
                                                    IEnumerable<SelectListItem> listOfValues,
                                                    RadioButtonLabelLayout labelLayout = RadioButtonLabelLayout.LabelTagContainsButtonThenText)
        {
            if (listOfValues == null) { return null; }
            var buttons= listOfValues.Select(item => RadioButtonFor(htmlHelper, expression, item, labelLayout));
            return MvcHtmlString.Create(buttons.Aggregate(new StringBuilder(), (sb, o) => sb.Append(o), sb => sb.ToString()));
        }

        /// <summary> Create an <see cref="IEnumerable{T}"/> list of radio buttons ready for individual processing before rendering</summary>
        public static IEnumerable<MvcHtmlString> RadioButtonListFor<TModel, TProperty>(
                    this HtmlHelper<TModel> htmlHelper,
                    Expression<Func<TModel, TProperty>> expression,
                    IEnumerable<SelectListItem> listOfValues,
                    RadioButtonLabelLayout labelLayout)
        {
            if (listOfValues == null) { return new MvcHtmlString[0]; }
            return listOfValues.Select( item =>  RadioButtonFor(htmlHelper, expression, item, labelLayout) );
        }

        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(
                                HtmlHelper<TModel> htmlHelper, 
                                Expression<Func<TModel, TProperty>> expression, 
                                SelectListItem item, 
                                RadioButtonLabelLayout labelLayout)
        {
            var id = htmlHelper.IdFor(expression) + " " + item.Value;
            var radio = htmlHelper.RadioButtonFor(expression, item.Value, new {id}).ToHtmlString();
            var labelText = HttpUtility.HtmlEncode(item.Text);
            TagBuilder nestingLabel = null;
            switch (labelLayout)
            {
                case RadioButtonLabelLayout.LabelTagContainsTextThenButton:
                    nestingLabel = new TagBuilder("label") {InnerHtml = labelText + " " + radio};
                    return MvcHtmlString.Create(nestingLabel.ToString());
                case RadioButtonLabelLayout.LabelTagContainsButtonThenText:
                    nestingLabel = new TagBuilder("label") {InnerHtml = radio + " " + labelText};
                    return MvcHtmlString.Create(nestingLabel.ToString());
                case RadioButtonLabelLayout.SiblingBeforeButton:
                    return MvcHtmlString.Create(radio + " " + htmlHelper.Label(id, labelText));
                case RadioButtonLabelLayout.SiblingAfterButton:
                    return MvcHtmlString.Create(htmlHelper.Label(id, labelText) + " " + radio);
                default:
                    throw new ArgumentOutOfRangeException("labelLayout", labelLayout, 
                                "This is not a valid RadioButtonLayoutStyle for rendering a radio button");
            }
        }
    }

    public enum RadioButtonLabelLayout
    {
        LabelTagContainsButtonThenText = 0,
        LabelTagContainsTextThenButton = 1,
        SiblingBeforeButton = 2,
        SiblingAfterButton = 3,
    }