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POHow to create a business model wrapper for a generic database approach?
 

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  1. POHow to create a business model wrapper for a generic database approach?
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    <p>I'm currently facing a performance problem with creating POCO objects from my database. I'm using Entity Framework 4 as OR-Mapper. The whole application is a prototype for now.</p> <p>Let's assume I want to have some business objects like classes 'Printer' or 'Scanner'. Both classes inherit from a BaseClass called Product. The business classes exist.</p> <p>I try to use a more generic database approach. I don't want to create tables for "Printer" nor "Scanner". I want to have 3 tables: One called Product, and the other Property and PropertyValue (which stores all assigned values to a specific Product).</p> <p>In my business layer I do create a specific object like this:</p> <pre><code>public Printer GetPrinter(int IDProduct) { Printer item = new Printer(); // get the product object with EF // get all PropertyValues // (with Reflection) foreach property in item.GetType().GetProperties // { // property.SetValue("specific value") // } return item; } </code></pre> <p>This is how the EF model looks like: <img src="https://i.stack.imgur.com/rwADO.png" alt="enter image description here"></p> <p>Works fine so far. For now I'm doing performance tests for retrieving multiple sets.</p> <p>I've created a prototype and improved it several times to increase the performance. It is still far away from being usable. I takes 919ms to create 300 objects who only contain 3 properties.</p> <p>The reason for choosing such DB design is to have a generic database design. Adding new properties should only be done in the business model.</p> <p>Am I just being too stupid to create a performant way of retrieving xx objects or is my approach totally wrong? As far as I understand OR-Mapper, they are basically doing the same?</p>
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    1. COYou are using both reflection and a metatable in your approach - each of those techniques degrades performance. How about creating concrete classes and see how that performs?
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    2. CO@rsenna: By metatable you mean that the database rows are being mapped into the EF types?
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    3. CO`Property` and `PropertyValue` are metatables. They do not map directly to actual business entities; instead, they are used to generically define new "types" of entities (and their associated values). I agree this is a powerful (and sometimes very useful) approach, but you'll certainly lose performance going that way.
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