Essential Books

Validation Attributes

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Validation attributes are used to enforce various validation rules in a declarative fashion on classes or class members. All validation attributes derive from the ValidationAttribute base class.

Example: RequiredAttribute

When validated through the ValidationAttribute.Validate method, this attribute will return an error if the Name property is null or contains only whitespace. 

public class ContactModel
{
    [Required(ErrorMessage = "Please provide a name.")]
    public string Name { get; set; }
}

Example: StringLengthAttribute

The StringLengthAttribute validates if a string is less than the maximum length of a string. It can optionally specify a minimum length. Both values are inclusive. 

public class ContactModel
{
    [StringLength(20, MinimumLength = 5, ErrorMessage = "A name must be between five and twenty characters.")]
    public string Name { get; set; }
}

Example: RangeAttribute

The RangeAttribute gives the maximum and minimum value for a numeric field. 

public class Model
{
    [Range(0.01, 100.00,ErrorMessage = "Price must be between 0.01 and 100.00")]
    public decimal Price { get; set; }
}

Example: CustomValidationAttribute

The CustomValidationAttribute class allows a custom static method to be invoked for validation. The custom method must be static ValidationResult [MethodName] (object input). 

public class Model
{
    [CustomValidation(typeof(MyCustomValidation), "IsNotAnApple")]
    public string FavoriteFruit { get; set; }
}

Method declaration: 

public static class MyCustomValidation
{
    public static ValidationResult IsNotAnApple(object input)
    {
        var result = ValidationResult.Success;

        if (input?.ToString()?.ToUpperInvariant() == "APPLE")
        {
            result = new ValidationResult("Apples are not allowed.");
        }

        return result;
    }
}
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Data Annotation:
* Data Annotation Basics
* Creating a custom validation attribute
* Manually Execute Validation Attributes
* EditableAttribute data modeling attribute
* Validation Attributes
* DisplayNameAttribute display attribute
Table Of Contents
0 Getting Started With C#
1 Literals
2 Operators
3 Conditional Statements
4 Equality Operator
5 Equals and GetHashCode
6 Null-Coalescing Operator
7 Null-Conditional Operators
8 nameof Operator
9 Verbatim String
10 Common String Operations
11 String Format
12 String Concatenate
13 String Manipulation
14 String Interpolation
15 String Escape Sequences
16 StringBuilder
17 Regex
18 DateTime
19 Arrays
20 On Algorithm for circular rotation of an array
21 Enum
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31 Built-in Types
32 Aliases of built-in types
33 Anonymous types
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35 Type Conversion
36 Casting
37 Nullable types
38 Constructors and Finalizers
39 Access Modifiers
40 Interfaces
41 Static Classes
42 Singleton Implementation
43 Dependency Injection
44 Partial class and methods
45 Object Initializers
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47 Extension Methods
48 Named Arguments
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50 Data Annotation
51 Keywords
52 Recursion
53 Naming Conventions
54 XML Documentation Comments
55 Comments and regions
56 Inheritance
57 Generics
58 Using Statement
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63 LINQ to Objects
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69 C# 7.0 Features
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74 Exception Handling
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77 Read and Understand Stack trackes
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85 Properties
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87 INotifyPropertyChanged interface
88 Events
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90 Overload Resolution
91 Preprocessor directives
92 Structs
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94 Delegates
95 File and Stream IO
96 Networking
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100 Asynchronous Socket
101 Action Filters
102 Polymorphism
103 Immutability
104 Indexer
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106 Stream
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108 Stopwatches
109 Threading
110 Async/Await, BackgroundWorker, Task and Thread examples
111 Async Await
112 Synchronization Context in Async/Await
113 BackgroundWorker
114 Task Parallel Library
115 Making a variable thread safe
116 Lock Statement
117 Yield Keyword
118 Task Parallel Library TPL Dataflow Constructs
119 Functional Programming
120 Func delegates
121 Function with multiple return values
122 Binary Serialization
123 ICloneable
124 IComparable
125 Accessing Databases
126 Using SQLite
127 Caching
128 Code Contracts
129 Code Contracts and Assertions
130 Structural Design Patterns
131 Creational Design Patterns
132 Implementing Decorating Design Pattern
133 Implementing Flyweight Design Pattern
134 System.Management.Automation
135 Pointers
136 Pointers and Unsafe Code
137 Simulating C Unions with C# Structs
138 Reactive Extensions Rx
139 AsseblyInfo.cs examples
140 Creating Console Application
141 CLSCompliantAttribute
142 ObservableCollection
143 Hash Functions
144 Generating Random Numbers
145 Cryptography
146 Unsafe Code in .NET
147 C# Script
148 Runtime Compile
149 Interoperability
150 .NET Compiler Platform Roslyn
151 Creating Own MessageBox in Windows Form Application
152 Including Font Resources
153 Garbage Collector
154 Windows Communication Foundation
155 Contributors