Experience Sitecore ! | SXA: Implementing URL query parameter rendering variant with little efforts

Note! The code used in this post can be cloned from GitHib repository: SXA.Foundation.Variants

Got a requirement to display a value passed with a URL parameter on a page (URL decoded of course). I want to achieve the goal as quick as possible, with the minimum steps, ideally. So, here we go..

1. Just use existing VariantField (located at /sitecore/templates/Foundation/Experience Accelerator/Rendering Variants/VariantField). When copying, ensure you keep new variant field template outside of Experience Accelerator folder (to avoid it being lost on future SXA upgrade), ideally somewhere within a folder with serialization configured.

2. Remove unwanted fields from a new template. I left only a few I felt necessary, but you may end up having even less. Another thing I've done at this step was adding a user-friendly label to the field, to avoid editors' confusion with a misleading naming:

3. Then you need to create a model. As the simplest, I inherited from VariantField

public class VariantQueryString : VariantField
{
    public VariantQueryString(Item variantItem) : base(variantItem)
    {
    }
}

With a parser, I only process those fields I will be using - what I kept from the previous step:

public class ParseQueryStringField : ParseField
{
    public override ID SupportedTemplateId => Constants.RenderingVariants.Templates.QueryString;

    public override void TranslateField(ParseVariantFieldArgs args)
    {
        ParseVariantFieldArgs variantFieldArgs = args;

        variantFieldArgs.TranslatedField = new VariantQueryString(args.VariantItem)
        {
            // this property is reused under different purpose rather than named - it stores URL parameter name
            FieldName = args.VariantItem[Constants.RenderingVariants.Fields.QueryField.FieldName],

            Tag = args.VariantItem.Fields[Constants.RenderingVariants.Fields.QueryField.Tag].GetEnumValue(),
            CssClass = args.VariantItem[Constants.RenderingVariants.Fields.QueryField.CssClass],
            Prefix = args.VariantItem[Constants.RenderingVariants.Fields.QueryField.Prefix],
            Suffix = args.VariantItem[Constants.RenderingVariants.Fields.QueryField.Suffix],
            RenderIfEmpty = args.VariantItem[Constants.RenderingVariants.Fields.QueryField.RenderIfEmpty] == "1"
        };
    }
}

Also reference IDs of these fields within Constants class:

public static class Constants
{
    public static class RenderingVariants
    {
        public static class Fields
        {
            public static class QueryField
            {
                public static ID Tag { get; } = new ID("{F556DEDD-5D6B-4FFF-A904-E4C65AB0E698}");
                public static ID CssClass { get; } = new ID("{B3B6B300-1704-493B-999C-AD21CCE58FEF}");
                public static ID FieldName { get; } = new ID("{9D3717EF-CD09-4D98-8C4A-914299503626}");
                public static ID Prefix { get; } = new ID("{5844C4AA-5E48-4721-8E30-91646E430C83}");
                public static ID Suffix { get; } = new ID("{0EFAF48E-E0DD-4408-80D3-4C001101E834}");
                public static ID RenderIfEmpty { get; } = new ID("{E14C3930-FE6C-48AC-99D8-C6867B489066}");
            }
        }
    }
}

4. Finally, implementing RenderQueryStringField class. Nothing complex - just getting a value from the query string, wrapping it with a selected tag/styles and rendering it into the page. Also, there's a fallback scenario for Experience Editor when a given parameter is missing from URL but component needs to be visible.

public class RenderQueryStringField : RenderVariantField
{
    public override Type SupportedType => typeof(VariantQueryString);

    public override RendererMode RendererMode => RendererMode.Html;

    public override void RenderField(RenderVariantFieldArgs args)
    {
        var variantField = args.VariantField as VariantQueryString;
        if (variantField != null)
        {
            args.ResultControl = RenderQueryStringValue(variantField, args);
            args.Result = RenderControl(args.ResultControl);
        }
    }

    protected virtual Control RenderQueryStringValue(VariantField variantField, RenderVariantFieldArgs args)
    {
        var queryString = HttpContext.Current.Request.QueryString;

        if (!string.IsNullOrEmpty(variantField.FieldName) && !string.IsNullOrWhiteSpace(variantField.Tag))
        {
            if (queryString.HasKeys() && queryString[variantField.FieldName] != null)
            {
                var tag = new HtmlGenericControl(variantField.Tag);
                AddClass(tag, (variantField.CssClass + " " + GetFieldCssClass(variantField.FieldName)).Trim());
                tag.InnerText = queryString[variantField.FieldName];
                return tag;
            }

            if (args.IsControlEditable && PageMode.IsExperienceEditorEditing)
            {
                return GetVariantFieldNameLiteral(variantField.FieldName);
            }
        }

        return new LiteralControl();
    }

    protected virtual HtmlGenericControl GetVariantFieldNameLiteral(string parameterName)
    {
        var missingField = new HtmlGenericControl("span");
        missingField.Attributes.Add("class", "missing-field-hint");
        missingField.InnerText = $"[{parameterName}] URL paramenter";
        return missingField;
    }
}

5. I am adding new field variant into existing Foundation project, but if you haven't got one - you might create it. Do not forget to include config patches. something like below:

?xml version="1.0" encoding="utf-8" ?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <pipelines>
      <parseVariantFields>
        <processor type="Platform.Foundation.Variants.Pipelines.VariantFields.QueryString.ParseQueryStringField, Platform.Foundation.Variants" resolve="true" patch:before="processor[@type='Sitecore.XA.Foundation.RenderingVariants.Pipelines.ParseVariantFields.ParseField, Sitecore.XA.Foundation.RenderingVariants']" />
      </parseVariantFields>
      <renderVariantField>
        <processor type="Platform.Foundation.Variants.Pipelines.VariantFields.QueryString.RenderQueryStringField, Platform.Foundation.Variants" resolve="true" patch:before="processor[@type='Sitecore.XA.Foundation.RenderingVariants.Pipelines.RenderVariantField.RenderVariantField, Sitecore.XA.Foundation.RenderingVariants']"  />
      </renderVariantField>
    </pipelines>
  </sitecore>
</configuration>

6. You might consider adding a new variant field into Insert options. Once done, add it as you normally do with variant fields: