Fake Data

Fake Data Seeder

Agent: Chikondi Banda — Senior Backend Engineer

Create a database seeder for $ARGUMENTS.

Prerequisites

• Model exists in app/models/
• Migration has been run on dev DB (go run . artisan migrate)

Step 1: Read the Model

Read app/models/<entity_name>.go to understand:

• All fields and their types
• Which fields are required vs nullable (*string, *time.Time, etc.)
• Enum/status values (check request validators in app/http/requests/)
• Relationships (FK fields)

Step 2: Create the Seeder File

Create database/seeders/<entity_name>_seeder.go:

package seeders

import (
	"github.com/goravel/framework/facades"
	"books-database/app/models"
	"time"
)

type EntitySeeder struct {
}

// Signature The name and signature of the seeder.
func (s *EntitySeeder) Signature() string {
	return "EntitySeeder"
}

// Run executes the seeder logic.
func (s *EntitySeeder) Run() error {
	// Check if table already has data (idempotent)
	var count int64
	count, err := facades.Orm().Query().Model(&models.Entity{}).Count()
	if err != nil {
		return err
	}
	if count > 0 {
		facades.Log().Infof("EntitySeeder: Skipping - table already has %d records", count)
		return nil
	}

	entities := []models.Entity{
		// ... 25-50 records ...
	}

	for _, entity := range entities {
		if err := facades.Orm().Query().Create(&entity); err != nil {
			return err
		}
	}

	return nil
}

Data Generation Rules

Minimum Records: 25

Generate at least 25 records to ensure meaningful testing of:

• Pagination (default page size is typically 10-20)
• Sorting (needs diverse values to verify order)
• Search (needs varied text to test matching)
• Filters (needs records in each status/category)

Status/Enum Distribution

Distribute records across all enum values:

// For a 2-value enum (ACTIVE/INACTIVE) with 30 records:
// ~20 ACTIVE, ~10 INACTIVE

// For a 4-value enum (AVAILABLE/BORROWED/MAINTENANCE/RESERVED) with 50 records:
// ~20 AVAILABLE, ~12 BORROWED, ~10 MAINTENANCE, ~8 RESERVED

Every enum value must have at least 3 records so filter tabs show meaningful results.

Data Diversity for Sorting

Ensure fields have diverse values that produce a clear sort order:

// GOOD — names that sort differently
{FirstName: "Alice", ...},
{FirstName: "Zara", ...},
{FirstName: "Michael", ...},

// BAD — all similar names
{FirstName: "John", ...},
{FirstName: "John", ...},
{FirstName: "Jane", ...},

For date fields, spread across multiple years:

parseDate("2020-03-15"),
parseDate("2022-07-22"),
parseDate("2024-01-10"),

For numeric fields (price, amount), use varied values:

Price: 9.99,
Price: 24.50,
Price: 149.99,

Nullable Fields

Mix nil and populated values for optional fields:

// ~70% populated, ~30% nil for optional fields
{Bio: strPtr("A detailed biography..."), Email: strPtr("alice@example.com")},
{Bio: nil, Email: strPtr("bob@example.com")},
{Bio: strPtr("Another bio"), Email: nil},
{Bio: nil, Email: nil},

Helper Functions

// String pointer helper
func strPtr(s string) *string { return &s }

// Date pointer helper (reuse if already defined in another seeder)
func parseDate(dateStr string) *time.Time {
	if dateStr == "" {
		return nil
	}
	t, err := time.Parse("2006-01-02", dateStr)
	if err != nil {
		return nil
	}
	return &t
}

Important: Check if parseDate or strPtr already exist in another seeder file before redefining them (Go won't allow duplicate function names in the same package).

FK Relationships

If the entity references another entity via FK:

// Option A: Set FK to known seeded IDs (if parent seeder runs first)
{AuthorID: uintPtr(1), ...},
{AuthorID: uintPtr(2), ...},
{AuthorID: nil, ...},  // Some records without FK (tests nullable FK)

// Option B: Look up parent IDs dynamically
var authors []models.Author
facades.Orm().Query().Find(&authors)
// Use authors[0].ID, authors[1].ID, etc.

Realistic Data

Use contextually appropriate data, not "Test Entity 1":

Group records by category/theme with comments for readability:

entities := []models.Entity{
    // Category A
    {Name: "...", ...},
    {Name: "...", ...},

    // Category B
    {Name: "...", ...},
    {Name: "...", ...},
}

Step 3: Register in DatabaseSeeder

Edit database/seeders/database_seeder.go to include the new seeder:

func (s *DatabaseSeeder) Run() error {
    // ... existing seeders ...

    // Run the entity seeder
    entitySeeder := &EntitySeeder{}
    if err := entitySeeder.Run(); err != nil {
        return err
    }

    return nil
}

Step 4: Register in kernel.go

Edit database/kernel.go to add the seeder:

func (kernel Kernel) Seeders() []seeder.Seeder {
    return []seeder.Seeder{
        &seeders.DatabaseSeeder{},
        &seeders.BookSeeder{},
        &seeders.RBACSeeder{},
        &seeders.ConfigSeeder{},
        &seeders.EntitySeeder{},  // Add here
    }
}

Step 5: Run the Seeder

# Run all seeders
go run . artisan db:seed

# Or run specific seeder
go run . artisan db:seed --seeder=EntitySeeder

Verify

# 1. Project compiles
go build ./...

# 2. Seeder runs without errors
go run . artisan db:seed --seeder=EntitySeeder

# 3. Verify records exist
# Check via API or database client

Idempotency (CRITICAL)

The seeder MUST be idempotent — running it multiple times should not create duplicate records.

Two patterns:

Pattern A: Count Check (simple, used by ConfigSeeder)

var count int64
count, _ = facades.Orm().Query().Model(&models.Entity{}).Count()
if count > 0 {
    return nil  // Skip if any records exist
}

Pattern B: Upsert by Unique Field (for re-seeding)

for _, entity := range entities {
    var existing models.Entity
    err := facades.Orm().Query().Where("email = ?", entity.Email).First(&existing)
    if err != nil {
        // Not found, create it
        facades.Orm().Query().Create(&entity)
    }
    // Already exists, skip
}

Prefer Pattern A for simplicity. Use Pattern B only if you need to update existing seed data.

Data Checklist

Before finishing, verify:

• At least 25 records
• Every enum/status value has 3+ records
• Nullable fields mix nil and populated values
• Text fields have diverse values (for sorting/search)
• Date fields span multiple years (for sorting)
• Numeric fields have varied values (for sorting)
• FK fields mix populated and nil (if nullable)
• Seeder is idempotent (check before insert)
• Registered in database_seeder.go and kernel.go
• go build ./... passes
• go run . artisan db:seed --seeder=EntitySeeder runs successfully

Reference

• Book seeder: database/seeders/book_seeder.go (50 records, grouped by genre)
• Config seeder: database/seeders/config_seeder.go (idempotent with count check)
• Database seeder: database/seeders/database_seeder.go (orchestrator)
• Kernel registration: database/kernel.go

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