Ltree Visualizer

A golang library to visualize or display postgres ltree type data directly from Postgres DB using DOT language and Graphviz.

What is Ltree?

Ltree is a data type which is used to represent the hierarchical tree-like structures in flat rows and columns in postgres DB For more info-refer this https://www.postgresql.org/docs/9.1/ltree.html

Sample Hierarchy:

why do we need this library ?

Ltree Labels are separated using Dot . like 1.2.3.4 and it is not easy to visualize like a tree.

This Library can produce output into two different formats:

• DOT Graph
• Image

DOT Graph:

DOT is a graph description language, using this language we can represent Directed, Undirected and FlowCharts. https://en.wikipedia.org/wiki/DOT_(graph_description_language)

digraph graphname {
    a -> b -> c;
    b -> d;
}

Config:

//Visualizer config
type Visualizer struct {
    LogLevel    log.Level
    RankDir     string
    PostgresURI string //Example postgresql://postgres:postgres@localhost:5432/taxonomy?sslmode=disable
    Query       string //select id, name, path from table1 //columns specified in this example should match or use resultset alias if your column names are different
    FetchFromDB bool
}

RankDir: Sets the direction of tree layout(https://www.graphviz.org/docs/attrs/rankdir/) and supported values are

• TB (Top to Bottom)
• RL (Right to Left)
• LR (Left to Right)
• BT (Bottom to Top) Note: Default is TB

FilePath: FilePath to save the image, this parameter is optional for GenerateDotGraph. Note: Default value of FilePath is graph.png

You can generate image of your ltree data using two ways:

• Directly fetch the data from your Postgres DB
• using Interim JSON file

DB Way (Directly fetch the data from your Postgres DB):

//Visualizer config
type Visualizer struct {
    LogLevel    log.Level
    RankDir     string
    PostgresURI string //Example postgresql://postgres:postgres@localhost:5432/taxonomy?sslmode=disable
    Query       string //select id, name, path from table1 //columns specified in this example should match or use resultset alias if your column names are different
    FetchFromDB bool
}

1. Provide PostgresURI which your app can connect Eg: postgresql://postgres:postgres@localhost:5432/taxonomy?sslmode=disable
2. Provide Query to fetch the data of your Ltree and your query result set should contain id, name, path
3. Set FetchFromDB to true

  import "github.com/jinagamvasubabu/ltreevisualizer"
  import "github.com/sirupsen/logrus"
 
  l := ltreevisualizer.Visualizer{
        PostgresURI: "postgresql://postgres:postgres@localhost:5432/taxonomy?sslmode=disable",
        Query: "select id as id, name as name,path as path from table"
  }
  resp, err := l.ConvertLtreeDataToImage(context.Background(), ltreevisualizer.VisualizerSchema{})
  fmt.Println(resp)

Using Interim Json File:

If you don't want to connect to DB and fetch the results then you can follow this way by using interim JSON file

//VisualizerSchema Contract to send to ltreevisualizer
type VisualizerSchema struct {
	Data []data `json:"data"`
}

type data struct {
	ID   int32  `json:"id"`
	Name string `json:"name"`
	Path string `json:"path"`
	Type string `json:"type"`
}

Refer data.json file under examples directory for sample data

• get LtreeVisualizer

  go get github.com/jinagamvasubabu/ltreevisualizer

• import and use it like below for to generate the output in DOT graph string:

  import "github.com/jinagamvasubabu/ltreevisualizer"
  import "github.com/sirupsen/logrus"
 
  l := ltreevisualizer.Visualizer{}
  resp, err := l.GenerateDotGraph(context.Background(), //json data)
  fmt.Println(resp)

• import and use it like below for to generate the output as an image:

  import "github.com/jinagamvasubabu/ltreevisualizer"
  import "github.com/sirupsen/logrus"
 
  l := ltreevisualizer.Visualizer{}
  err := l.ConvertLtreeDataToImage(context.Background(), //json data)

Note: This will create a graph.png image if you don't specify Filepath

You can refer examples directory for more info

How to test?

Refer visualizer_test.go for sample tests