edgedb-delete-checker

main.go

package main

import (
	"flag"
	"fmt"
	"io/fs"
	"io/ioutil"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Checker finds the links with deletion rules from the esdl files in the dir.
type Checker struct {
	Dir   string
	Links []Link
}

// Link represents a link in the esdl file.
type Link struct {
	Source   string // source type name
	Target   string // target type name
	Name     string // link name
	OnDelete string // on delete constraint
}

// String implements the Stringer interface.
func (l Link) String() string {
	switch l.OnDelete {
	case "allow":
		return fmt.Sprintf("If you delete %s, it will be deleted from %s (via .%s), and %s will stay", l.Target, l.Source, l.Name, l.Source)
	case "delete source":
		return fmt.Sprintf("If you delete %s, all linked %s will be deleted (via .%s)", l.Target, l.Source, l.Name)
	case "restrict":
		return fmt.Sprintf("If you try to delete %s that is referenced by %s (via .%s), it'll return an error", l.Target, l.Source, l.Name)
	default:
		return fmt.Sprintf("Unknown on delete constraint %s", l.OnDelete)
	}
}

func main() {
	var dir = flag.String("dir", ".", "directory with dbschema/.esdl files for your project")
	flag.Parse()

	c := Checker{
		Dir: *dir,
	}
	// find all dbschema/.esdl files in the directory
	err := filepath.WalkDir(*dir, func(s string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}

		if d.IsDir() {
			return nil
		}

		if filepath.Ext(s) != ".esdl" {
			return nil
		}

		return c.processESDL(s)
	})
	if err != nil {
		fmt.Println("[ERROR]:", err)
		os.Exit(1)
	}

	// sort by target for output
	sort.Slice(c.Links, func(i, j int) bool {
		return c.Links[i].Target < c.Links[j].Target
	})

	for _, link := range c.Links {
		fmt.Println(link)
	}

	fmt.Println()
	fmt.Println("See details on: https://www.edgedb.com/docs/datamodel/links#ref-datamodel-link-deletion")
}

func (c *Checker) processESDL(path string) error {
	data, err := ioutil.ReadFile(path)
	if err != nil {
		return fmt.Errorf("read file: %w", err)
	}

	// find lines theat contain "link "
	// and print them
	currentType := ""
	lines := strings.Split(string(data), "\n")
	for i, line := range lines {
		lastLine := i == len(lines)-1
		line = strings.TrimSpace(line)

		// save current type (esdl can contain many types
		if strings.Contains(line, "type ") {
			currentType = strings.Split(line, " ")[1]
			continue
		}

		if strings.Contains(line, "link ") {
			// peek the next line and check if it contains "on target delete"
			var onDelete string = "restrict"
			if !lastLine {
				nextLine := strings.TrimSpace(lines[i+1])
				if strings.Contains(nextLine, "on target delete") {
					if strings.Contains(nextLine, "allow") {
						onDelete = "allow"
					} else if strings.Contains(nextLine, "delete source") {
						onDelete = "delete source"
					}
				}
			}

			// strip required/multi
			line = strings.ReplaceAll(line, "required ", "")
			line = strings.ReplaceAll(line, "multi ", "")

			// split by spaces
			fields := strings.Fields(line)
			var name, target string

			name = fields[1]
			target = fields[3]

			// skip backlinks
			if strings.HasPrefix(target, ".<") {
				continue
			}

			// cleanup
			if strings.HasPrefix(name, "`") {
				name = strings.Trim(name, "`")
			}
			if strings.HasSuffix(target, ";") {
				target = strings.TrimSuffix(target, ";")
			}

			link := Link{
				Source:   currentType,
				Target:   target,
				Name:     name,
				OnDelete: onDelete,
			}
			c.Links = append(c.Links, link)
		}
	}
	return nil
}