ASNApalooza 2014 session: Stop validating user input like a rookie

1. Stop validating user input like a
rookie
Server side data validation using data annotations and
the .NET validator class
Presented by Tim Daniels
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2. Server side validation
• Takes place during a post back
• When the user request requires server resources
• Use in conjunction with client side validation
• Malicious users can easily bypass client side validation
• Client side validation provides a better user experience
• A more responsive web page
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3. Server side validation
• A server side validation design pattern;
• Validation rules defined at the domain object model
level
• Each domain entity contains its own specific data
validation rules
• A validation class that is reusable by all domain objects
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4. The .Net Validator Class
• A helper class for validating objects
• Capable of validating all properties of an object
• Dependent on data annotation attributes
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5. The .Net Validator Class
• A member of the System.ComponentModel.DataAnnotations
name space
• A static class
• Does not require instantiation
• We will utilize the TryValidateObject method
• The Details
MSDN Validator Class
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6. The TryValidateObject Method
• A public method of the Validator class
• Capable of validating all properties of an object
• Returns a value of Type: System.Boolean
• true if the object validates; otherwise false
• The Details
• MSDN Validator.TryValidateObject Method
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7. The TryValidateObject Method
• Requires four arguments passed to it;
1. Type: System.Object
• The object to Validate
2. Type: ValidationContext Class
• The Context that describes the object to validate
3. Type: Collections.Generic.Icollection<ValidationResult>
• A Collection to hold each failed validation
4. Type: System.Boolean
• true to validate all properties
• false only required attributes are validated
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8. The Object to Validate
BegClass CustomerAccess(*Public)
begconstructor Access(*Public)
endconstructor
dclprop Number type(*decimal) access(*public) attributes(Key(), ScaffoldColumn(*false))
dclprop CustomerName type(*string) access(*public) attributes(DisplayAttribute(Name:="Name"), RequiredAttribute(), +
StringLengthAttribute(40, ErrorMessage:="Name cannot be longer than 40 characters"))
dclprop Address type(*string) access(*public) attributes(DisplayAttribute(Name:="Street Address"), RequiredAttribute())
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9. The Validation Context Class
• Describes the context in which a validation check is performed
• The object to be validated is placed into a context suitable for input to the
Validator class
• The object to be validated is passed to the constructor of the Validator class
• The Details
• MSDN Validation Context Class
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10. The Validation Result Class
• Represents a container for the results of a validation
request
• Properties;
• Error Message
• The error message associated with the validation
• Member Name
• The name of the property validated
• The Details
• MSDN ValidationResult Class
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11. A Boolean specifies which properties to validate
• True
• Validate all properties
• False
• Only required attributes are validated
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12. Coding the Customer Validator Example
First add a reference to this assembly:
System.ComponentModel.DataAnnotations
Add this using statement:
Using System.ComponentModel.DataAnnotations
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13. Customer Validator Demonstration
Unit Test
• Visual Studio Test Explorer
• Test Validator
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