C#•4mo ago

Building a Blazor `RenderFragment` in base razor component to be used in derived?

Hey. So I have a base razor component that I want to derive from multiple times, as there will be a lot of duplicated code between the multiple derivations. One thing I have stumbled into, is that I have a title which is largely similar between all the derived components. For this, I currently have the following:

protected virtual string ObjectName => "Item";

protected RenderFragment TitleFragment() => builder =>
{
    builder.OpenComponent<MudText>(0);
    builder.AddAttribute(1, nameof(MudText.Typo), Typo.h6);
    builder.AddAttribute(2, nameof(MudText.Class), "mr-10");

    builder.AddAttribute(3, nameof(MudText.ChildContent), (RenderFragment) ((builder2) =>
    {
        builder2.OpenComponent<MudIcon>(4);
        builder2.AddAttribute(5, nameof(MudIcon.Class), "mr-3 mb-n1");
        if (IsCreating)
            builder2.AddAttribute(6, nameof(MudIcon.Icon), Icons.Material.Filled.Add);
        else
            builder2.AddAttribute(6, nameof(MudIcon.Icon), Icons.Material.Filled.Edit);
        builder2.CloseComponent();
        if(IsCreating)
            builder2.AddContent(7, $"Create {ObjectName}");
        else
            builder2.AddContent(7, $"Edit {ObjectName}");
    }));
    builder.CloseComponent();
};

protected virtual string ObjectName => "Item";

protected RenderFragment TitleFragment() => builder =>
{
    builder.OpenComponent<MudText>(0);
    builder.AddAttribute(1, nameof(MudText.Typo), Typo.h6);
    builder.AddAttribute(2, nameof(MudText.Class), "mr-10");

    builder.AddAttribute(3, nameof(MudText.ChildContent), (RenderFragment) ((builder2) =>
    {
        builder2.OpenComponent<MudIcon>(4);
        builder2.AddAttribute(5, nameof(MudIcon.Class), "mr-3 mb-n1");
        if (IsCreating)
            builder2.AddAttribute(6, nameof(MudIcon.Icon), Icons.Material.Filled.Add);
        else
            builder2.AddAttribute(6, nameof(MudIcon.Icon), Icons.Material.Filled.Edit);
        builder2.CloseComponent();
        if(IsCreating)
            builder2.AddContent(7, $"Create {ObjectName}");
        else
            builder2.AddContent(7, $"Edit {ObjectName}");
    }));
    builder.CloseComponent();
};

This works, and in my derived razor components I can invoke TitleFragment() and get the title that I desire. However, I wasn't sure if there was a way to create a RenderFragment in such a way without using the RenderTreeBuilder? Can I instead somehow declare this as razor syntax somewhere within my base razor component, or is this my only option?

7 Replies

Anu6is•4mo ago

can't you just make a component that you'd reuse?

Pingu•4mo ago

i could, thats another option... But I was wondering if there was a way to build up a render fragment within a component without doing so using the Builder approach

Anu6is•4mo ago

not that i'm aware

Jimmacle•4mo ago

if you do it in the .razor file you can use razor markup inside the method

Pingu•4mo ago

How would I do that? (confused how that would look sorry)

Jimmacle•4mo ago

example from one of mine

@code
{
    private RenderFragment SortHeader(ListProjects.Sort sort, SortDirection initialDirection = SortDirection.None)
    {
        return
            @<MudTh Style="white-space: nowrap;">
                <MudTableSortLabel
                    T="ListProjects.Response.Item"
                    SortLabel="@sort.ToString("G")"
                    InitialDirection="@initialDirection">
                    @sort.Humanize(LetterCasing.Title)
                </MudTableSortLabel>
            </MudTh>;
    }
}

@code
{
    private RenderFragment SortHeader(ListProjects.Sort sort, SortDirection initialDirection = SortDirection.None)
    {
        return
            @<MudTh Style="white-space: nowrap;">
                <MudTableSortLabel
                    T="ListProjects.Response.Item"
                    SortLabel="@sort.ToString("G")"
                    InitialDirection="@initialDirection">
                    @sort.Humanize(LetterCasing.Title)
                </MudTableSortLabel>
            </MudTh>;
    }
}

Pingu•4mo ago

ah ok makes sense. Didn't realise that worked like that... Interesting. 🙂 Thanks 🙂

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Building a Blazor `RenderFragment` in base razor component to be used in derived?