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Overview

Insert operations in ChameleonDB provide a safe, validated way to create new records in your database. All inserts go through a three-stage validation pipeline to ensure data integrity.

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Basic Insert

The simplest insert requires setting values for all required fields: 
import (
    "context"
    "github.com/chameleon-db/chameleondb/chameleon/pkg/engine"
    "github.com/google/uuid"
)

ctx := context.Background()

result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    Set("name", "Ana Garcia").
    Execute(ctx)

if err != nil {
    log.Fatal(err)
}

fmt.Printf("User created: %v\n", result.ID)

​
Insert with Default Values

Fields with defaults in your schema don’t need to be set: 
// Schema defines: created_at: timestamp default now()
result, err := eng.Insert("Post").
    Set("id", uuid.New().String()).
    Set("title", "My First Post").
    Set("content", "Hello, world!").
    Set("author_id", userID).
    // published defaults to false
    // created_at defaults to now()
    Execute(ctx)

​
Validation Pipeline

Every insert goes through three validation stages:

​
1. Schema Validation

Verifies that:
  • Entity exists in schema
  • All fields are defined
  • Types match schema definitions
result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", 12345). // Wrong type!
    Execute(ctx)

// Error: Type mismatch: field 'email' expects string, got int

​
2. Constraint Validation

Enforces:
  • NOT NULL constraints
  • UNIQUE constraints
  • Field presence requirements
result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    // Missing required field 'name'
    Execute(ctx)

// Error: NotNullError: Field 'name' cannot be null

​
3. Database Validation

Final checks at database level:
  • Foreign key constraints
  • Unique constraint violations
  • Database-specific rules
result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]"). // Email already exists
    Set("name", "Ana").
    Execute(ctx)

// Error: UniqueConstraintError: Field 'email' must be unique
//        Value: [email protected] already exists
//        Suggestion: Use a different value or update the existing record

​
Error Handling

ChameleonDB provides typed errors for precise error handling: 
import "errors"

result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    Set("name", "Ana").
    Execute(ctx)

if err != nil {
    var uniqueErr *engine.UniqueConstraintError
    if errors.As(err, &uniqueErr) {
        // Handle duplicate entry
        return fmt.Errorf("email already registered: %w", err)
    }
    
    var fkErr *engine.ForeignKeyError
    if errors.As(err, &fkErr) {
        // Handle invalid reference
        return fmt.Errorf("invalid reference: %w", err)
    }
    
    var notNullErr *engine.NotNullError
    if errors.As(err, &notNullErr) {
        // Handle missing required field
        return fmt.Errorf("missing required field: %w", err)
    }
    
    // Unknown error
    return fmt.Errorf("insert failed: %w", err)
}

​
Insert with Relations

When inserting records with foreign keys, ensure parent records exist: 
// First, create the user
userResult, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    Set("name", "Ana").
    Execute(ctx)

if err != nil {
    log.Fatal(err)
}

// Then create posts referencing the user
postResult, err := eng.Insert("Post").
    Set("id", uuid.New().String()).
    Set("title", "First Post").
    Set("content", "Hello, world!").
    Set("author_id", userResult.ID). // Reference to User
    Execute(ctx)

if err != nil {
    log.Fatal(err)
}
If you try to insert a record with an invalid foreign key reference, you’ll get a ForeignKeyError:
result, err := eng.Insert("Post").
    Set("id", uuid.New().String()).
    Set("title", "Orphan Post").
    Set("author_id", "invalid-uuid"). // User doesn't exist
    Execute(ctx)

// Error: ForeignKeyError: Invalid reference
//        Field 'author_id' references non-existent User

​
Debug Mode

Use .Debug() to see the generated SQL: 
result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    Set("name", "Ana").
    Debug(). // Shows SQL
    Execute(ctx)

// Output:
// [SQL] Insert User
// INSERT INTO users (id, email, name) VALUES ($1, $2, $3)
// [ARGS] [550e8400-e29b-41d4-a716-446655440000, [email protected], Ana]

​
Repository Pattern

Recommended pattern for production applications: 
package repository

import (
    "context"
    "github.com/chameleon-db/chameleondb/chameleon/pkg/engine"
    "github.com/google/uuid"
)

type UserRepository struct {
    eng *engine.Engine
}

func NewUserRepository(eng *engine.Engine) *UserRepository {
    return &UserRepository{eng: eng}
}

func (r *UserRepository) Create(ctx context.Context, email, name string) (*engine.InsertResult, error) {
    return r.eng.Insert("User").
        Set("id", uuid.New().String()).
        Set("email", email).
        Set("name", name).
        Execute(ctx)
}

​
Best Practices

​
Always Generate UUIDs

import "github.com/google/uuid"

// Good: Generate UUID in application
result, err := eng.Insert("User").
    Set("id", uuid.New().String()).
    Set("email", "[email protected]").
    Set("name", "Ana").
    Execute(ctx)

// Bad: Don't rely on database to generate IDs
result, err := eng.Insert("User").
    Set("email", "[email protected]").
    Set("name", "Ana").
    Execute(ctx) // Missing 'id' will cause NotNullError

​
Validate Before Insert

func (r *UserRepository) Create(ctx context.Context, email, name string) error {
    // Validate email format
    if !isValidEmail(email) {
        return fmt.Errorf("invalid email format")
    }
    
    // Validate name length
    if len(name) < 2 {
        return fmt.Errorf("name too short")
    }
    
    // Perform insert
    _, err := r.eng.Insert("User").
        Set("id", uuid.New().String()).
        Set("email", email).
        Set("name", name).
        Execute(ctx)
    
    return err
}

​
Handle Errors Gracefully

import "net/http"

func createUserHandler(w http.ResponseWriter, r *http.Request) {
    result, err := repo.Create(r.Context(), email, name)
    if err != nil {
        var uniqueErr *engine.UniqueConstraintError
        if errors.As(err, &uniqueErr) {
            http.Error(w, "Email already registered", http.StatusConflict)
            return
        }
        
        http.Error(w, "Internal server error", http.StatusInternalServerError)
        return
    }
    
    w.WriteHeader(http.StatusCreated)
    json.NewEncoder(w).Encode(result)
}

​
Next Steps

Update Operations

Learn how to safely update existing records

Delete Operations

Remove records with safety guards

Safety Guards

Understand ChameleonDB’s mutation safety features

Error Handling

Complete error handling reference

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