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Mastering Entity Framework Core 2.0

You're reading from   Mastering Entity Framework Core 2.0 Dive into entities, relationships, querying, performance optimization, and more, to learn efficient data-driven development

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Product type Paperback
Published in Dec 2017
Publisher Packt
ISBN-13 9781788294133
Length 386 pages
Edition 1st Edition
Languages
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Author (1):
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Prabhakaran Anbazhagan Prabhakaran Anbazhagan
Author Profile Icon Prabhakaran Anbazhagan
Prabhakaran Anbazhagan
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Toc

Table of Contents (13) Chapters Close

Preface 1. Kickstart - Introduction to Entity Framework Core 2. The Other Way Around – Database First Approach FREE CHAPTER 3. Relationships – Terminology and Conventions 4. Building Relationships – Understanding Mapping 5. Know the Validation – Explore Inbuilt Validations 6. Save Yourself – Hack Proof Your Entities 7. Going Raw – Leveraging SQL Queries in LINQ 8. Query Is All We Need – Query Object Pattern 9. Fail Safe Mechanism – Transactions 10. Make It Real – Handling Concurrencies 11. Performance – It's All About Execution Time 12. Isolation – Building a Multi-Tenant Database

MaxLength field validation


The MaxLength validation is helpful for creating constraints on certain fields such as Username, Zip code, and so on. We will investigate MaxLength validation in this section.

The validation error can be captured in the  MaxLengthdata annotation if the field value length is greater than the configured length. For instance, if the maximum length is configured as 30, then if the length of total characters provided in the field is greater than 30, the max length validation error would be thrown.

The MaxLength attribute/data annotation can be configured as follows:

    public class RegistrationViewModel
    {
      [Required(ErrorMessage = "Username is required")]
      [MinLength(6, ErrorMessage = "Username needs minimum 6 
       characters")] 
      [MaxLength(30)]
      public string Username { get; set; }
      // Code removed for brevity
    }

If the field value does not meet the maximum length requirement, then the validation error, The field Username must be a...

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