chrusty / go-tableprinter

Print a formatted table from GoLang interfaces

go-tableprinter

Print a formatted table from GoLang interfaces. This can be useful if you're building a CLI, or just prefer a more human-readable interpretation of your data.

Features

• Handles structs / maps / slices / interfaces
• Colums are alphabetically ordered by default (this can be disabled if you prefer)
• Tables can optionally have borders (disabled by default)
• Requires no modification to existing data structures
• Nil values are listed as <nil>
• Interfaces can be printed straight to stdout
• Optionally they can also be printed to any io.Writer (buffer, stderr, file etc)
• You can also use the Marshal() function to render a table as bytes
• Uses the String() method to render values (when available)

Limitations

• Currently unable to print unexported struct fields, similar to JSON or YAML (listed as <unexported>)

Usage

You can use this package to print tables either by using the default *Printer, or making your own (with specific config).

Using the default printer

package main

import (
	"fmt"

	"github.com/chrusty/go-tableprinter"
)

type exampleType struct {
	Name           string
	Age            int
	FavouriteWords []string
	Tags           map[string]interface{}
	IsCrufty       bool
}

func main() {

	// Prepare some example data:
	example := exampleType{
		Name:           "prawn",
		Age:            15248,
		FavouriteWords: []string{"Cruft", "Crufts", "Crufty"},
		Tags: map[string]interface{}{
			"crufty": true,
			"grumpy": true,
		},
		IsCrufty: true,
	}

	// Disable sorting then print using the default printer:
	tableprinter.SetSortedHeaders(false)
	tableprinter.Print(example)
	fmt.Printf("\n\n")

	// Re-enable sorting then print using the default printer:
	tableprinter.SetSortedHeaders(true)
	tableprinter.Print(example)
	fmt.Printf("\n\n")

	// See what happens when we print a map:
	tableprinter.Print(example.Tags)
	fmt.Printf("\n\n")

	// See what happens when we print a slice:
	tableprinter.Print(example.FavouriteWords)
	fmt.Printf("\n\n")

	// Set borders then print using the default printer:
	tableprinter.SetBorder(true)
	tableprinter.Print(example)
}

  NAME  |  AGE  |    FAVOURITEWORDS     |             TAGS             | ISCRUFTY
+-------+-------+-----------------------+------------------------------+----------+
  prawn | 15248 | [Cruft Crufts Crufty] | map[crufty:true grumpy:true] | true


   AGE  |    FAVOURITEWORDS     | ISCRUFTY | NAME  |             TAGS
+-------+-----------------------+----------+-------+------------------------------+
  15248 | [Cruft Crufts Crufty] | true     | prawn | map[crufty:true grumpy:true]


  CRUFTY | GRUMPY
+--------+--------+
  true   | true


  VALUE
+--------+
  Cruft
  Crufts
  Crufty


+-------+-----------------------+----------+-------+------------------------------+
|  AGE  |    FAVOURITEWORDS     | ISCRUFTY | NAME  |             TAGS             |
+-------+-----------------------+----------+-------+------------------------------+
| 15248 | [Cruft Crufts Crufty] | true     | prawn | map[crufty:true grumpy:true] |
+-------+-----------------------+----------+-------+------------------------------+

Using a custom printer

package main

import (
	"fmt"

	"github.com/chrusty/go-tableprinter"
)

type exampleType struct {
	Name           string
	Age            int
	FavouriteWords []string
	Tags           map[string]interface{}
	IsCrufty       bool
}

func main() {

	// Make a custom printer with the default values:
	printer := tableprinter.New().WithBorders(true)

	// Prepare some example data (this time a slice):
	examples := []exampleType{
		{
			Name:           "prawn",
			Age:            15248,
			FavouriteWords: []string{"Cruft", "Crufts", "Crufty"},
			Tags: map[string]interface{}{
				"crufty": false,
				"grumpy": true,
			},
			IsCrufty: false,
		},
		{
			Name:           "CruftLord",
			Age:            99999,
			FavouriteWords: []string{"CruftLord", "CruftMaster", "Darth Crufter"},
			Tags: map[string]interface{}{
				"crufty": true,
				"grumpy": false,
			},
			IsCrufty: true,
		},
	}

	// Use the custom printer to print the examples:
	if err := printer.Print(examples); err != nil {
		panic(err)
	}

	// Use the Marshal method to get bytes:
	tableBytes, _ := printer.Marshal(examples)
	fmt.Printf("\nThis table is %dB\n", len(tableBytes))
}

+-------+---------------------------------------+----------+-----------+-------------------------------+
|  AGE  |            FAVOURITEWORDS             | ISCRUFTY |   NAME    |             TAGS              |
+-------+---------------------------------------+----------+-----------+-------------------------------+
| 15248 | [Cruft Crufts Crufty]                 | false    | prawn     | map[crufty:false grumpy:true] |
| 99999 | [CruftLord CruftMaster Darth Crufter] | true     | CruftLord | map[crufty:true grumpy:false] |
+-------+---------------------------------------+----------+-----------+-------------------------------+

This table is 630B

History

ToDo

• Optional row numbering

0.4.0

• Detects and uses String() methods to render values

0.3.0

• Optionally sort columns by headers

0.2.0

• Use go-spew to format values
• Provide a default tableformatter
• Make Borders optional

0.1.0

• Handle generic interfaces (default)
• Handle pointers
• Handle structs
• Handle maps
• Handle slices of the above