What causes "FTP config is nil" in gofr-dev/gofr?

Provide a non-nil *ftp.Config with host/port before connecting.

FTP config is nil

Error message

FTP config is nil

What it means

errFTPConfigNil is returned by the FTP storage adapter's Connect when its internal *Config pointer is nil. The adapter cannot dial an FTP server without connection parameters, so it refuses to start. It is a programming/configuration error, not a transient network condition.

Source

Thrown at pkg/gofr/datasource/file/ftp/storage_adapter.go:19

package ftp

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"path"
	"strings"
	"time"

	"github.com/jlaffaye/ftp"
	"gofr.dev/pkg/gofr/datasource/file"
)

var (
	// Storage adapter errors.
	errFTPConfigNil            = errors.New("FTP config is nil")
	errFTPClientNotInitialized = errors.New("FTP client is not initialized")
	errEmptyObjectName         = errors.New("object name is empty")
	errInvalidOffset           = errors.New("invalid offset: must be >= 0")
	errEmptySourceOrDest       = errors.New("source and destination names cannot be empty")
	errSameSourceAndDest       = errors.New("source and destination are the same")
	errFailedToCreateReader    = errors.New("failed to create reader")
	errFailedToCreateWriter    = errors.New("failed to create writer")
	errObjectNotFound          = errors.New("object not found")
	errFailedToGetObjectAttrs  = errors.New("failed to get object attrs")
	errFailedToDeleteObject    = errors.New("failed to delete object")
	errFailedToListObjects     = errors.New("failed to list objects")
	errFailedToListDirectory   = errors.New("failed to list directory")
	errWriterAlreadyClosed     = errors.New("writer already closed")
	errFTPConfigInvalid        = errors.New("invalid FTP configuration: host and port are required")
)

// Config represents the FTP configuration.
type Config struct {

View on GitHub (pinned to 187eb24962)

Solutions

Provide a non-nil *ftp.Config with host/port before connecting.
Guard at startup: if cfg == nil, fail fast with a clear configuration error instead of reaching Connect().
Use ftp.New(&ftp.Config{...}) so defaults (DialTimeout, location) are applied.

Example fix

// before
adapter := &ftp.StorageAdapter{} // cfg nil
adapter.Connect()
// after
adapter := ftp.New(&ftp.Config{Host: host, Port: 21})

Defensive patterns

Strategy: validation

Validate before calling

if cfg == nil {
    return nil, fmt.Errorf("ftp config required: set host and port")
}
fs := ftp.New(cfg)

Type guard

func hasFTPConfig(c *ftp.Config) bool { return c != nil && c.Host != "" }

Try / catch

// Connect is async and logs; guard construction instead
if cfg == nil {
    log.Fatal("FTP config is nil; refusing to start FTP filesystem")
}
fs := ftp.New(cfg)

Prevention

Never pass nil to ftp.New; always supply a populated Config.
Validate config presence at application startup, not at connect time.
If config is optional in your app, skip creating the FTP filesystem entirely when absent.

When it happens

Trigger: Calling Connect() on a storageAdapter created with a nil cfg (e.g. ftp.New(nil) paths where config was never populated, or manual adapter construction with &storageAdapter{cfg: nil}).

Common situations: Passing nil to constructors and assuming defaults; zero-value struct usage before initialization; DI frameworks injecting a nil config when no FTP config is present in the environment.

Related errors

AI-assisted analysis of gofr-dev/gofr@187eb24962 (2026-09-01). Data as JSON: /api/errors/1f637ad4dcea3807. Report an issue: GitHub.