Jsonnet - JSON data template language

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Jsonnet: Google’s JSON data template language.

Features: Support for comments, references, arithmetic, conditional operators, array and object inclusion, introduction, functions, local variables, inheritance, etc.

Website: jsonnet.org

GitHub:github.com/google/json…

Example official language: github.com/google/json…

A, install,

brew install jsonnet
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Second, the tool

VSCode
Plug-in:Jsonnet NG: Supports syntax highlighting and saves previews

After installing the plug-in, click the preview button in the upper right corner

The default preview result is yamL. You can search for jsonnet Preview in Settings to find the corresponding setting and select JSON.

Three, characteristics

1, field,

define

Field names can be unquoted, but must be quoted if there are Spaces

{
  field1: 'lxf1',
  "field 2": 'lxf2'
}
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Hidden fields

The fields defined are not output to the JSON result

Language :: 'jsonnet', LXF: {lang: $. Language, author: name}}Copy the code

Results:

{
    "lxf": {
        "author": "LXF"."lang": "jsonnet"}}Copy the code

2, comments,

Single line comments// Single-line comments

/* Multi-line comments */
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3. String

quotes

Single quotes are no different from double quotes

A single line verbatim string

# Single-line verbatim strings: use @{"single line": @'hello \ lxf'
}
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Results:

{
  "single line": "hello \\ lxf"
}
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Multiline verbatim string

# multi-line string word by word: use | | | {"multiple line": |||
  	hello
  	lxf
  |||,
}
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Results:

{
  "multiple line": "hello\nlxf\n"
}
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Joining together

{
  pi:: 3.1415926,
  format: 'Hello, %s' % 'lxf',
  concat: 'Hello, ' + 'lxf',
  format1: |||
    hello
    pi=%(pi)0.2f
  ||| % self,
}
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Results:

{
    "concat": "Hello, lxf"."format": "Hello, lxf"."format1": "Hello \ npi = 3.14 \ n"
}
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4, variables,

define

uselocalThe keyword defines a variable
Variables defined next to fields are marked with commas (.), other cases define variables with a semicolon (;) at the end

local github = 'https://github.com/LinXunFeng'; Variables that are not defined next to fields end in a semicolonLanguage :: 'jsonnet', LXF: {target: $. Language, author: name, by: self.author, address: github } }Copy the code

Results:

{
  "lxf": {
    "address": "https://github.com/LinXunFeng"."author": "LinXunFeng"."by": "LinXunFeng"."target": "jsonnet"}}Copy the code

reference

Variable name: Proximity principle
selfKeyword: Point to the current object
$Keyword: Point to the root object
[' field name ']: is used to find a field
The field name: Fetch a field, but the field name must conform to the normal naming standard (cannot start with a number, cannot contain Spaces, etc.).
[number]: Is used to fetch array elements
Allowed long path
Strings and arrays allow imagespythonUse array slices likearr[10:20:2]

local github = 'https://github.com/LinXunFeng';
{
  local name = 'LXF',
  language:: 'jsonnet',
  lxf: {
    target: $.language,
    author: name,
    by: self.author,
    address: github,
    languages: ['oc', 'swift', 'python'],
    nums: [1.8.11.22.33.44.55],
  },
  lqr: {
    local name = "fsa_fullstackaction",
    languages: ['java', 'kotlin', 'python'],
    scores: $.lxf.nums[1:3],
    organization: name[4:],
    height: $['lxf'].nums[0] + 'm'
  },
}
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Results:

{
  "lqr": {
    "height": "1.8 m"."languages": [
      "java"."kotlin"."python"]."organization": "fullstackaction"."scores": [
      11.22]},"lxf": {
    "address": "https://github.com/LinXunFeng"."author": "LXF"."by": "LXF"."languages": [
      "oc"."swift"."python"]."nums": [
      1.8.11.22.33.44.55]."target": "jsonnet"}}Copy the code

5. Four operations

Support four operations, bit operations, comparison logic
+When a string is encountered in the operation, the numeric value is converted to a string for concatenation
Strings can be compared
useinKeyword to determine whether a field in the specified object

{
  info: {
    name: 'LinXunFeng'
  },
  ex1: (1 + 2) / 3 * 4,
  ex2: 1 << 2,
  ex3: 'a' <= 'b',
  ex4: 'a' == 'b',
  ex5: 5 + 6 + '1'+1,
  ex6: 'name' in self.info,
}
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Results:

{
    "ex1": 4."ex2": 4."ex3": true."ex4": false."ex5": "1111"."ex6": true."info": {
        "name": "LinXunFeng"}}Copy the code

6, functions,

Support for positional, named, and default parameters
Support closures
A number of commonly used functions are already defined in Standard Library

local addNumber(number) = function(x) number + x;
local add2 = addNumber(2);
local add3 = addNumber(3); {# closures: closures: [add2(2),
    add3(5Local sayHello(name) =' hello %s' % name, sum(x, y):: x + y, newPerson(name=' LXF ', age=18, gender='male'):: {name: name, age: age, gender: gender,}, # call call_say_hello: sayHello(' LXF '), call_sum: $.sum(1, 2),
  lxf: $.newPerson(age=3),
  standard_lib: std.join(' ', std.split('foo/bar', '/')),
  len: [
    std.length('hello'),
    std.length([1.2.3])],}Copy the code

Results:

{
    "call_say_hello": "hello lxf"."call_sum": 3."closures": [
        4.8]."len": [
        5.3]."lxf": {
        "age": 3."gender": "male"."name": "lxf"
    },
    "standard_lib": "foo bar"
}
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7. Conditional statements

Expression: if a then b else C, else is optional, returns null by default

local Person(isFemale) = {
  name: 'lxf',
  age: 18,
  gender: if isFemale then 'female' else 'male',
  [if isFemale then 'clothing']: 'dress',
};

{
  condition1: if 2 > 1 then 'true' else 'false',
  condition2: if 2 < 1 then 'true',
  male: Person(false),
  female: Person(true),}Copy the code

Results:

{
    "condition1": "true"."condition2": null."female": {
        "age": 18."clothing": "dress"."gender": "female"."name": "lxf"
    },
    "male": {
        "age": 18."gender": "male"."name": "lxf"}}Copy the code

8. Object merge

use+Operator to combine two objects, and if a field conflict is encountered, the fields in the object on the right are used
Right object can be usedsuperKeywords refer to fields in the left object
use+ :When the operator combines two objects, the right object overwrites the existing fields in the left object, and the missing fields are added

# +
local base = {
    f: 2,
    g: self.f + 100}; base + { f:5,
    old_f: super.f,
    old_g: super.g,
}

##################################

# +:
local base = {
    override: {
        x: 1,
    },
    composite+: {
        x: 1,}}; { override: { y:2, 
      z: 3 
    },
    composite: { 
      y: 4, 
      z: 5 
    },
} + base
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Results:

# +
{
    "f": 5."g": 105."old_f": 2."old_g": 105
}

##################################

# +:

{
    "composite": {
        "x": 1."y": 4."z": 5
    },
    "override": {
        "x": 1}}Copy the code

9. Import the template

Similar to copy/paste code
It can also be used to importjsonThe original data
The suffix of a template file must be.libsonnet
useimportKeyword to import the template content and store it using the specified variable

Content of the template

{
  newPerson(
    name,
    country='China',
    age=18
  ):: {
    name: name,
    country: country,
    age: age,
    belly: [],
    eat(food):: self + {
      belly+: [food],
    },
  },
}
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Use the template

Localpersontemplate = import 'libs/lxflib.libsonnet'; libsonnet = libsonnet; personTemplate .newPerson(name='lxf', age=3)
  .eat('rice')
  .eat('pear')
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Results:

{
    "age": 3."belly": [
        "rice"."pear"]."country": "China"."name": "lxf"
}
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Four, terminal use

1, basic use

#Simple code can be run directly using -e
jsonnet -e '{key: 1+2}'
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View the conversion results of the Jsonnet file

jsonnet shuttle.jsonnet
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2. Specify the library path

If there is an imported template file in the Jsonnet file, but only write the name of the template file, not the path

Libsonnet local personTemplate = import 'lxflib.libsonnet';Copy the code

In this case, direct execution of the command will report an error

RUNTIME ERROR: couldn't open import "lxflib.libsonnet": no match locally or in the Jsonnet library paths.
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At this point you have two choices

Option 1: Honestly write the full relative path when importing

local personTemplate = import 'libs/lxflib.libsonnet';
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Option 2: Use the -j

parameter

 jsonnet -J ./libs shuttle.jsonnet
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3. Export the result to a file

Export json files using jsonnet files

jsonnet shuttle.jsonnet -o shuttle.json
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4. Multiple file output

Jsonnet also supports scenarios where multiple JSON files are generated using a single Jsonnet file, such as both A.JAXon and B.JAXon

{
  "a.json": {
    x: 1,
    y: $["b.json"].y,
  },
  "b.json": {
    x: $["a.json"].x,
    y: 2,}}Copy the code

The command

#Jsonnet -m 
      
        Jsonnet file
      
jsonnet -m . multiple_output.jsonnet
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Results:

$ cat a.json 
{
   "x": 1,
   "y": 2
}

$ cat b.json 
{
   "x": 1,
   "y": 2
}
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Five, the application of

In order to improve our work efficiency, it is often to organize and save some commonly used commands.

I do, for example, and use it with Shuttle, a shortcut menu that uses JSON to configure terminal commands.

As shown in the figure below, I added the command that triggers the remote Jenkins to package, but the remote build machine for some reason switches between two fixed IP addresses, so I added two, only the IP is different

However, in addition to the packaging function, other functions are related to the build machine IP, so once we add an IP, we have to change a lot of things, and also find that the command is the same, if one day the command is changed… 😭

So in cases like this, we need the help of Jsonnet to simplify things.

On the left of the image below, I’ve defined some common templates under the libs directory and put some constant configurations into the constant.libsonnet template file

In the shuttle. Jsonnet file, the entire shuttle configuration is defined

The good thing about this is that when the new person comes in and you need them to be able to step in immediately to pack and distribute, you just need to configure the Shuttle.

Configuring the Shuttle simply requires adjusting the constant.libsonnet file and executing one line of command!

jsonnet . shuttle.jsonnet -o ~/.shuttle.json
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Jsonnet – JSON data template language

A, install,

Second, the tool

Three, characteristics

1, field,

define

Hidden fields

2, comments,

3. String

quotes

A single line verbatim string

Multiline verbatim string

Joining together

4, variables,

define

reference

5. Four operations

6, functions,

7. Conditional statements

8. Object merge

9. Import the template

Four, terminal use

1, basic use

2. Specify the library path

3. Export the result to a file

4. Multiple file output

Five, the application of

Jsonnet – JSON data template language

A, install,

Second, the tool

Three, characteristics

1, field,

define

Hidden fields

2, comments,

3. String

quotes

A single line verbatim string

Multiline verbatim string

Joining together

4, variables,

define

reference

5. Four operations

6, functions,

7. Conditional statements

8. Object merge

9. Import the template

Four, terminal use

1, basic use

2. Specify the library path

3. Export the result to a file

4. Multiple file output

Five, the application of

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