string flowerList = string.Empty;
foreach (var flower in Plants.Where(x => x.Status == PlantStatus.Active))
{
flowerList = string.IsNullOrWhiteSpace(flowerList)
? "<li>" flower.Colour " " flower.Priority " " flower.Category "</li>"
: flowerList "<li>" flower.Colour " " flower.Priority " " flower.Category "</li>" ;
}
I have the above code to display a C# list data data in a html page. How can i group my flowerList
html out put by flower.Category
.
For each Category, I would wish to have flower.Category
as the group header and then under it list the related records.
CodePudding user response:
The code is already using LINQ. Grouping in LINQ is performed by the GroupBy
operator. It's not a good idea to put the query in the foreach
clause though, even for simple queries. Modifying it becomes a lot harder.
This snippet groups by category and then generates the HTML string. Instead of concatenating strings though it uses a StringBuilder to avoid creating temporary strings.
var categories=Plants.Where(x => x.Status == PlantStatus.Active)
.GroupBy(x=>x.Category);
var builder=new StringBuilder();
foreach(var category n categories)
{
builder.AppendFormat("<div>\n<h1>{0}</h1>\n", category.Key);
foreach(var flower in category)
{
builder.AppendFormat("<li>{0} {1}</li>\n",
flower.Colour,
flower.Priority);
}
builder.AppendLine("</div>");
}
var html=builder.ToString();
Template Engines
Generating strings like this works only for simple HTML though. Even this code is becoming hard to maintain. In such cases it's better to use a template engine like Visual Studio's T4 or the more modern Scriban or Handlebars.NET.
The following example uses Scriban
var template = Template.Parse(@"
<H1>Flowers by Category</H1>
{{ for category in Categories }}
<div>
<h2>{{ category.key }}</h2>
<ul>
{{ for flower in category }}
<li>{{ flower.Colour }} {{ flower.Priority }}</li>
{{ end }}
</ul>
</div>
{{ end }}
");
var html = template.Render(new { Categories = categories });
It's now a lot easier to understand what the output will look like, edit the template and find any errors
CodePudding user response:
Here is one possible way to group the output by flower.Category:
string flowerList = string.Empty;
// Group the flowers by category
var flowerGroups = Plants
.Where(x => x.Status == PlantStatus.Active)
.GroupBy(x => x.Category);
// Iterate over the groups and create the HTML output
foreach (var group in flowerGroups)
{
// Create the header for the group
flowerList = "<h3>" group.Key "</h3>";
// Create a list of flowers in the group
flowerList = "<ul>";
foreach (var flower in group)
{
flowerList = "<li>" flower.Colour " " flower.Priority " " flower.Category "</li>";
}
flowerList = "</ul>";
}
This code will first group the flowers by flower.Category, then iterate over the groups and create a heading for each group followed by a list of flowers in that group. The final result will be a string containing the HTML output.
CodePudding user response:
var categories=Plants.Where(x => x.Status == PlantStatus.Active) .GroupBy(x=>x.Category);
var builder=new StringBuilder("
- ");
foreach(var plants in categories)
{
foreach(var plant in plants)
{
builder.AppendFormat("
- {0} {1} {2} \n", flower.Colour, flower.Priority, flower.Category); } } builder.AppendLine("
var html=builder.ToString();