Json generator

The simple console utility to generate JSON items according to the provided example composing JSON body and a set of functions that define the logic to generate new items.

The utility allows delivering the generated JSON to different sources such as an HTTP server, folder or file or console

Contents

• Overall
• Rules
• Generators
• How to use
  • From console
  • From dependency

Overall

Given template:

{
  "description": "the example how to create a json template to generate new jsons",
  "note": "the prefix | in a field name signals that the field carries a function to generate data.",
  "record": {
    "|type": "str_from_list(business,technical,analytical)", 
    "technical":{
       "|id": "uuid()",
       "|index": "seq()",
       "|updated_tm": "dt()",
       "|created_tm": "dt(%Y-%m-%d %H:%M:%S)"
     },
    "|is_active": "bool()",
    "|name": "str(10,customer)",
    "|email": "str(5,,@gmail.com)",
    "|code": "str(5,,'(code)')",
    "|dsc": "str(20)",
    "geo": {
        "|country": "str_from_file(jsons/countries,,)",
        "|city": "str_from_file(jsons/cities,'\n')",
        "|street": "str(10,,-street)",
        "|house": "int(1,1000)"
      },
    "|id_parent": "int_from_list(1,2,3,4,5,6,7)",
    "|related_records": "int(1,1000) -> array(5)"

  }
}

Generated json:

{
  "description": "the example how to create a json template to generate new jsons",
  "note": "the prefix | in a field name signals that the field carries a function to generate data.",
  "record": {
    "code": "Upaz2(code)",
    "dsc": "gLgvDinPZg1aMu9LpPyp",
    "email": "PMWtc@gmail.com",
    "geo": {
      "city": "Rome",
      "country": "Australia",
      "house": 770,
      "street": "7Ke4CAHWpk-street"
    },
    "id_parent": 7,
    "is_active": false,
    "name": "customerXgKChm5t2b",
    "related_records": [
      263,
      489,
      390,
      226,
      361
    ],
    "technical": {
      "created_tm": "2021-05-23 13:09:27",
      "id": "339b0ca7-0e00-4d6e-8073-d270d7d56e2e",
      "index": 1,
      "updated_tm": "2021-05-23 13:09:27"
    },
    "type": "analytical"
  }
}

Rules

Overall, if the field does not have a specific prefix, depicting that the field carries a generator function, the value of the field will be taken and returned in the result. Otherwise, if the field contains a prefix in its name the value is expected to be a string and describe the function to generate the values. By default the prefix is | like in the example:

{
  "|dynamic_field_with_generator": "seq()",
  "static_field": "constant"
}

*Note: the prefix sign can be changed if it interferes with the existing field into any other char.

Generators

Every generator has a following syntax: generator name ( arg1, arg2, ..)

If the generator contains another generator then the syntax obtain extra elements: internal generator (arg1, arg2, .. ) -> encompassing generator (arg1, arg2, ..)

The generators can have empty arguments: str(10,,postfix)

The string literals can be placed as an argument straightly or encompassed by the single quotes: str(10,literal,'with quotes')

List of generators:

How to use

From console

cargo install json-gen

json-gen  -f "file path" -r 10 --pretty --logs --to-folder folder --to-curl '-X POST ip'

Command line Arguments

note: for using --to-curl parameter the system needs to have the curl utility installed.

From dependency

json-gen="*"

use json_generator::json_template::JsonTemplate;
use json_generator::generate;
use serde_json::Value;

fn main() {
    let json_template:&str = "{\"|id\":\"seq()\"}";
    let mut json_template = JsonTemplate::from_str(json_template, "|").unwrap();
    let generated_value:Vec<Value> = generate(&mut json_template,10,true,&mut vec![]);
}

Senders

The function generate gets the last parameter it is an array of senders. Essentially, sender is a struct implementing a trait sender:

pub trait Sender {
    fn send(&mut self, json: &Value, pretty: bool) -> Result<String, GenError>;
}

and example of a simple implementation:

 use json_generator::sender::{Sender, ConsoleSender, string_from};
 use serde_json::Value;
 
impl Sender for ConsoleSender {
fn send(&mut self, json: &Value, pretty: bool) -> Result<String, GenError> {
    println!("{}",  string_from(json, pretty)?);
    Ok("the item has been sent to the console".to_string())
   }
 }

GenError

By default, everything is wrapped with Gen(erator)Error, the general structure to handle errors.

In general, it has the following bowels:

#[derive(Debug)]
pub struct GenError {
    reason: String,
    tpe: GenErrorType,
}

#[derive(Debug)]
pub enum GenErrorType {
    Parser,
    Sender,
    Generator,
    Common,
}

and provides the following methods to work with:

impl GenError {
    pub fn new_with(reason: &str) -> Self {..}
    pub fn new_with_in_parser(reason: &str) -> Self {..}
    pub fn new_with_in_sender(reason: &str) -> Self {..}
    pub fn new_with_in_generator(reason: &str) -> Self {..}
}