Using it standalone

filevalidator lives in its own Go module. You can import it without pulling in the filekit core or any storage drivers:

go get github.com/gobeaver/filekit/filevalidator

Validate an HTTP upload

package main

import (
    "net/http"

    "github.com/gobeaver/filekit/filevalidator"
)

var uploads = filevalidator.NewBuilder().
    MaxSize(10 * filevalidator.MB).
    AcceptImages().
    Extensions(".jpg", ".jpeg", ".png", ".webp").
    WithContentValidation().
    Build()

func handleUpload(w http.ResponseWriter, r *http.Request) {
    if err := r.ParseMultipartForm(32 << 20); err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }
    fh := r.MultipartForm.File["file"][0]

    if err := uploads.Validate(fh); err != nil {
        http.Error(w, err.Error(), http.StatusUnprocessableEntity)
        return
    }

    // safe to persist
}

Validate a stream you already have

import (
    "context"
    "io"

    "github.com/gobeaver/filekit/filevalidator"
)

func ingest(ctx context.Context, name string, size int64, body io.Reader) error {
    v := filevalidator.ForDocuments().Build()
    return v.ValidateReader(body, name, size)
}

ValidateReader reads the first ~512 bytes for MIME detection and runs the configured content validator. The reader is consumed only as far as the validator needs.

Validate a byte slice

v := filevalidator.NewBuilder().
    MaxSize(1 * filevalidator.MB).
    Accept("application/json").
    WithContentValidation().
    Build()

err := v.ValidateBytes(data, "config.json")

Validate a local file

err := filevalidator.ValidateLocalFile(v, "/tmp/upload.png")

Cancellation

All Validate* methods have a WithContext variant for cancellation:

err := v.ValidateWithContext(ctx, fh)

What you avoid by going standalone

Importing only filevalidator does not pull github.com/gobeaver/filekit, so you skip every driver dependency (AWS SDK, GCS SDK, Azure SDK, pkg/sftp, fsnotify, gobwas/glob, …). The validator module itself depends only on the Go standard library.