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<title>How to set columns on select using Entity Framework - Sipmann</title>
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<meta name="description" content="Did you know how much data you get back with your EF select? Learn how to specify which fields you would get back.">
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<h1><b><a href="https://www.sipmann.com/select_specific_fields_with_efcore.html" title="Permalink to How to set columns on select using Entity Framework">How to set columns on select using Entity Framework</a></b></h1>
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<i class="fa fa-calendar"></i><time class="w3-opacity" datetime="2020-10-28T19:00:00-03:00"> Wed 28 October 2020</time>
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<p><p>So, you use Entity Framework Core, and you usually code your selects like the following, maybe you are getting too much data.</p>
<div class="highlight"><pre><span></span><code><span class="kt">var</span> <span class="n">products</span> <span class="p">=</span> <span class="n">Products</span>
<span class="p">.</span><span class="n">Where</span><span class="p">(</span><span class="n">p</span> <span class="p">=></span> <span class="n">p</span><span class="p">.</span><span class="n">UnitsInStock</span> <span class="p">></span> <span class="m">0</span><span class="p">)</span>
<span class="p">.</span><span class="n">OrderBy</span><span class="p">(</span><span class="n">p</span> <span class="p">=></span> <span class="n">p</span><span class="p">.</span><span class="n">ProductName</span><span class="p">)</span>
<span class="p">.</span><span class="n">ToList</span><span class="p">()</span>
</code></pre></div>
<p>Running the query above, on my table, you'll get the following output, take a look at how many columns you are getting back from your database.</p>
<p><img alt="Screenshot with every single column" src="/images/ef_core_allcolumns.png"></p>
<p>In my case, I only care about the Title, PublishedData, and a small description. So to get back only these fields, we have a few options. In the first one, we'll set the fields and return them as a dynamic object, the second one, is to give the .NET a class to use. </p>
<div class="highlight"><pre><span></span><code><span class="kt">var</span> <span class="n">products</span> <span class="p">=</span> <span class="n">Products</span>
<span class="p">.</span><span class="n">Select</span><span class="p">(</span><span class="n">p</span> <span class="p">=></span> <span class="k">new</span> <span class="p">{</span><span class="n">p</span><span class="p">.</span><span class="n">ProductID</span><span class="p">,</span> <span class="n">p</span><span class="p">.</span><span class="n">ProductName</span><span class="p">,</span> <span class="n">p</span><span class="p">.</span><span class="n">UnitsInStock</span><span class="p">,</span> <span class="n">p</span><span class="p">.</span><span class="n">UnitPrice</span><span class="p">})</span>
<span class="c1">//.Select(p => new ProductDTO {p.ProductID, p.ProductName, p.UnitsInStock, p.UnitPrice})</span>
<span class="p">.</span><span class="n">Where</span><span class="p">(</span><span class="n">p</span> <span class="p">=></span> <span class="n">p</span><span class="p">.</span><span class="n">UnitsInStock</span> <span class="p">></span> <span class="m">0</span><span class="p">)</span>
<span class="p">.</span><span class="n">OrderBy</span><span class="p">(</span><span class="n">p</span> <span class="p">=></span> <span class="n">p</span><span class="p">.</span><span class="n">ProductName</span><span class="p">)</span>
<span class="p">.</span><span class="n">ToList</span><span class="p">()</span>
</code></pre></div>
<p><img alt="Screenshot with fewer columns and also fewer data size" src="/images/ef_core_less_columns.png"></p></p>
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<h4>Translations:</h4>
<ul>
<li><a href="../pt/select_specific_fields_with_efcore.html">pt - Como definir as colunas no select utilizando Entity Framework</a></li>
</ul>
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function w3_close() {
mySidebar.style.display = "none";
overlayBg.style.display = "none";
}
</script>
</body>
</html>