LINQ Tutorials

Tutorial Home › LINQ

#1 Introduction to LINQ

Basic looking for something with Where(...) and Any(...)

Resources

Learn how to leverage LINQ (Language Integrated Query) of C# to sort, filter, group content-items. This demo uses the following data in app:

Persons - various people who are used in the data. A person can also have one or many favorite books.
Books - books people wrote or contributed to. Books have authors and

Some notes before we start

All our code uses some general stuff explained here:

to enable LINQ commands we always need:
@using System.Linq
most of the code starts by retrieving a list of Books and Authors. This is done using:
App.Data["Books"]
Since we want to use dynamic types (which lets us write things like book.Name, we usually wrap it with:
AsList(App.Data["Books"])
The compiler often can't guess object types we are using, we often need to cast lists to:
IEnumerable<dynamic>
The easiest way is to just run it through AsList(original as object).
The as object part necessary because of limitations in Razor.

Query with Params - Run multiple times

#1 Introduction to LINQ

Basic looking for something with Where(...) and Any(...)

Source Code of this file

Below you'll see the source code of the file. Note that we're just showing the main part, and hiding some parts of the file which are not relevant for understanding the essentials. Click to expand the code

@inherits Custom.Hybrid.Razor14
@using ToSic.Razor.Blade;
<!-- unimportant stuff, hidden -->
@using System.Linq;


<div @Sys.PageParts.InfoWrapper()>
  @Html.Partial("../shared/DefaultInfoSection.cshtml")
  <div @Sys.PageParts.InfoIntro()>
    <p>
      Learn how to leverage LINQ (Language Integrated Query) of C# to sort, filter, group content-items. This demo uses the following data in app:
    </p>
    <ul>
      <li><strong>Persons</strong> - various people who are used in the data. A person can also have one or many favorite books. </li>
      <li><strong>Books</strong> - books people wrote or contributed to. Books have authors and </li>
    </ul>
  </div>
</div>

<h2>Some notes before we start</h2>
<p>
  All our code uses some general stuff explained here:
</p>

<ul>
  <li>
    to enable LINQ commands we always need: <br>
    <code>@@using System.Linq</code></li>
  <li>
    most of the code starts by retrieving a list of <strong>Books</strong> and <strong>Authors</strong>. This is done using: <br>
    <code>App.Data["Books"]</code></li>
  <li>
    Since we want to use <code>dynamic</code> types (which lets us write things like <code>book.Name</code>, we usually wrap it with: <br>
    <code>AsList(App.Data["Books"])</code>
  </li>
  <li>
    The compiler often can't guess object types we are using, we often need to cast lists to: <br>
    <code>IEnumerable&lt;dynamic&gt;</code> <br>
    The easiest way is to just run it through <code>AsList(original as object)</code>. <br>
    The <code>as object</code> part necessary because of limitations in Razor. 
  </li>
</ul>

@* Footer *@
@Html.Partial("../Shared/Layout/FooterWithSource.cshtml", new { Sys = Sys })