Karma Database Package

The karma/database package provides utilities to work with PostgreSQL using Go structs. It helps you insert, update, and parse query results without writing verbose SQL.

📦 Installation

go get github.com/MelloB1989/karma

🔌 Database Connection

Use the built-in PostgresConn function to connect to your database using .env values.

import "github.com/MelloB1989/karma/database"

db, err := database.PostgresConn()
if err != nil {
    log.Fatal(err)
}
defer db.Close()

You can optionally pass pool config:

opts := database.PostgresConnOptions{
	MaxOpenConns:    ptr(20),
	MaxIdleConns:    ptr(10),
	ConnMaxLifetime: ptr(300), // in seconds
}
db, err := database.PostgresConn(opts)

🔧 Environment Configuration

Your .env file must define one of the following:

# Default fallback
DATABASE_URL=postgres://username:password@localhost:5432/mydb?sslmode=disable

# Optional environment-based configs
ENVIRONMENT=dev
DEV_DATABASE_URL=postgres://dev_user:dev_pass@localhost:5432/devdb?sslmode=disable
PROD_DATABASE_URL=postgres://prod_user:prod_pass@db.example.com:5432/proddb?sslmode=require

Karma will choose the right URL based on the ENVIRONMENT variable.

🧩 Struct Definition Rules

To enable Karma’s ORM helpers, your struct must follow specific tag and format rules.

type User struct {
    TableName string                 `karma_table:"users" json:"-"`
    Id        int                    `json:"id"`
    Username  string                 `json:"username"`
    Email     string                 `json:"email"`
    Tags      []string               `json:"tags" db:"tags"`
    Metadata  map[string]interface{} `json:"metadata" db:"metadata"`
}

✅ Guidelines

CamelCase field names in Go
snake_case keys for JSON and DB tags
For arrays/maps/structs, always add db:"<column_name>" for PostgreSQL compatibility
Include TableName field with karma_table tag for ORM functionality

🔧 Function Reference

FetchColumnNames

func FetchColumnNames(db *sqlx.DB, tableName string) ([]string, error)

Returns a list of column names for a given table.

cols, err := database.FetchColumnNames(db, "users")
fmt.Println(cols) // ["id", "username", "email", ...]

ParseRows

func ParseRows(rows *sql.Rows, dest interface{}) error

Scans SQL rows into a slice of structs.

var users []User
rows, _ := db.Query("SELECT * FROM users")
err := database.ParseRows(rows, &users)

dest must be a pointer to a slice of structs.

InsertStruct

func InsertStruct(db *sqlx.DB, tableName string, data interface{}) error

Inserts a struct into a table.

user := User{
    Username: "john_doe",
    Email:    "john@example.com",
    Tags:     []string{"admin", "beta"},
    Metadata: map[string]interface{}{"source": "referral"},
}
err := database.InsertStruct(db, "users", &user)

UpdateStruct

func UpdateStruct(db *sqlx.DB, tableName string, data interface{}, conditionField string, conditionValue interface{}) error

Updates a table row based on a given condition.

user.Email = "new@email.com"
err := database.UpdateStruct(db, "users", &user, "id", user.Id)

🧪 Full Example

package main

import (
	"log"
	"github.com/MelloB1989/karma/database"
)

type User struct {
	TableName string                 `karma_table:"users" json:"-"`
	Id        int                    `json:"id"`
	Username  string                 `json:"username"`
	Email     string                 `json:"email"`
	Tags      []string               `json:"tags" db:"tags"`
	Metadata  map[string]interface{} `json:"metadata" db:"metadata"`
}

func main() {
	db, err := database.PostgresConn()
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	// Insert
	user := User{Username: "alice", Email: "alice@ex.com", Tags: []string{"early"}, Metadata: map[string]interface{}{"lang": "en"}}
	if err := database.InsertStruct(db, "users", &user); err != nil {
		log.Fatal(err)
	}

	// Update
	user.Email = "alice@updated.com"
	if err := database.UpdateStruct(db, "users", &user, "id", user.Id); err != nil {
		log.Fatal(err)
	}

	// Fetch
	rows, err := db.Query("SELECT * FROM users")
	if err != nil {
		log.Fatal(err)
	}
	var users []User
	if err := database.ParseRows(rows, &users); err != nil {
		log.Fatal(err)
	}
	log.Println("Fetched users:", users)
}

🧠 Pro Tips

For dynamic field updates (only update changed fields), use sqlx.NamedExec manually.
Use karma/config for all env loading. Never hardcode secrets.
Combine with karma/middleware to add request logging or panic recovery around DB operations.

Get Started

The Karma Suite packages

database Package

Karma Database Package

📦 Installation

🔌 Database Connection

🔧 Environment Configuration

🧩 Struct Definition Rules

✅ Guidelines

🔧 Function Reference

FetchColumnNames

ParseRows

InsertStruct

UpdateStruct

🧪 Full Example

🧠 Pro Tips

​Karma Database Package

​📦 Installation

​🔌 Database Connection

​🔧 Environment Configuration

​🧩 Struct Definition Rules

​✅ Guidelines

​🔧 Function Reference

​FetchColumnNames

​ParseRows

​InsertStruct

​UpdateStruct

​🧪 Full Example

​🧠 Pro Tips

Karma Database Package

📦 Installation

🔌 Database Connection

🔧 Environment Configuration

🧩 Struct Definition Rules

✅ Guidelines

🔧 Function Reference

FetchColumnNames

ParseRows

InsertStruct

UpdateStruct

🧪 Full Example

🧠 Pro Tips