DataGenerator

Data Generator. Give it a ⭐ if you find it useful.

ChangeLog

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${\color{grey}{Key \space features}}$

${\color{darkgreen}{Calculated \space properties}}$

Construct a property value using just generated values from the same object.

// Given: FirstName and LastName are randomly generated. The email is dynamically constructed. 
.Property(s => s.Email).Construct(s => $"{s.FirstName}.{s.LastName}@mycompany.com") 

${\color{darkgreen}{String \space templates}}$

Support placeholders for numbers, oneofs, resources, and file content, replacing them with values from the corresponding list.

A template like:

"Note: [number:100-999] [resource:Firstnames] [file:lastnames.txt:4-10] [oneof:Europe,America,Africa]"

could generate an output such as: Note: 137 Jessica Torres Africa.

Note

Specifying a range for numbers is required.

Note

The built-in Length(min, max) method is ignored when using templates.

${\color{blue}{Decorators}}$

Enhance the just generated random value using decorators.

.Property(s => s.Name)
    .Template("[resource:Nouns]")
    .Decorate(r => CapitalizeFirstLetter(r?.ToString()))

${\color{darkgreen}{Random \space generation \space rules}}$

Define rules for generating values, each associated with a probability.

// Generates a negative value in the range of [-5, -1) with a probability of 0.1 (10%).
.Property(s => s.Year)
    .Range(1,5)
    .GenerationRule("NegativeYear", 0.1, _ => Random.Shared.Next(-5, -1))

Note

The probability of using the default generation logic (P_d) — when no specific generation rules apply — is calculated as: P_d = 1 - ΣP_i. Where P_i represents the probability of each individual generation rule.

${\color{darkgreen}{Nullable \space rule}}$

Defines the probability of assigning a null value.

Note

The property type must be either nullable (T?) or a reference type with nullable annotations enabled (?).

// Precondition
class Student
{
    public string? FirstName {get; set; }
    public string LastName {get; set; }
}

// Great job :)
.Property(s => s.FirstName)
    .Template("[file:firstnames.txt]")
    .Nullable(0.25)

// Will throw an exception :(
.Property(s => s.FirstName)
    .Template("[file:lastnames.txt]")
    .Nullable(0.25)

${\color{darkgreen}{Predefined \space values}}$

Choose a value from the predefined collection.

.Property(s => s.Degree)
    .FromCollection(["Bachelor", "Master", "Doctor"])

${\color{darkgreen}{Ignore}}$

Excludes the property from the generation process.

scheme.ForType<StudentGroup>()
    .Ignore(s => s.CourseTeachers)

${\color{darkgreen}{Custom \space generators}}$

// A custom generator should inherit from `GeneratorBase<T>`
public class PhoneGenerator : GeneratorBase<string>
{
    private const char SpecialSymbol = '#';

    public override string CreateRandomValue(Property property)
    {
        var mask = property.GetValueRule("PhoneMask") ?? "### ### ###";

        var builder = new StringBuilder();
        Random random = GetRandomInstance(property);

        foreach (var c in mask.ToString()!)
            builder.Append(c != SpecialSymbol ? c : random.Next(0, 10).ToString());

        return builder.ToString();
    }
}

// Usage
.Property(s => s.Phone)
    .UseGenerator(new PhoneGenerator())
    .ValueRule("PhoneMask", "## ## ## ##")

${\color{black}{Generators}}$

• BooleanGenerator
• DateTimeGenerator
• DateTimeOffsetGenerator
• DecimalGenerator
• DoubleGenerator
• EmailGenerator
• EnumGenerator
• GuidGenerator
• IntGenerator
• IpGenerator
• PhoneGenerator
• SetGenerator
• StringGenerator

${\color{black}{Example}}$ ➫

var scheme = new DataScheme();

//StudentGroup
scheme.ForType<StudentGroup>()
    .Ignore(s => s.CourseTeachers)
    .Property(s => s.Name).Template("[resource:Nouns]").Decorate(r => Utility.CapitalizeFirstLetter(r?.ToString()))
    .Property(s => s.Students).Count(3, 5)
    .Property(s => s.ContactPhones).Count(2, 3).UseGenerator(new PhoneGenerator());

//Student
scheme.ForType<Student>()
    .Property(s => s.FirstName).Template("[resource:Firstnames:3-4]")
    .Property(s => s.LastName).Template("[file:lastnames.txt]:4-6").Nullable(0.25)
    .Property(s => s.Email).Construct(s => $"{Utility.BuildNameWithoutSpaces(s.FirstName, s.LastName)}" + 
                                           $"{TemplateProcessor.CreateValue(Random.Shared,"@[resource:Domains]")}")
    .Property(s => s.BirthDay).Range(DateTime.Today.AddYears(-60), DateTime.Today.AddYears(-16)).Nullable(0.1)
    .Property(s => s.Year).Range(1,5).GenerationRule("NegativeYear", 0.5, _ => Random.Shared.Next(-5, -1))
    .Property(s => s.Courses).Count(2,4)
    .Property(s => s.Degree).FromCollection(["Bachelor", "Master", "Doctor"])
    .Property(s => s.Note).Template("Note: [number:100-999] [resource:Firstnames] [file:lastnames.txt] [oneof:Europe,America,Africa].");

//Contact
scheme.ForType<Contact>()
    .Property(s => s.Phone).UseGenerator(new PhoneGenerator()).PhoneMask("## ## ## ##")
    .Property(s => s.Address).Template("[resource:Addresses]")
    .Property(s => s.IpAddress).UseGenerator(new IpGenerator()).Nullable(0.5);

var dataGenerator = new SimpleDataGenerator(scheme);
var randomStudentCollection = dataGenerator.GenerateForType<StudentGroup>();

${\color{black}{Default \space values}}$

The range default values can be overriden if necessary.