Package 'jsonStrings'

Title: Manipulation of JSON Strings
Description: Fast manipulation of JSON strings. Allows to extract or delete an element in a JSON string, merge two JSON strings, and more.
Authors: Stéphane Laurent [aut, cre], Niels Lohmann [cph] ('nlohmann/json' C++ library)
Maintainer: Stéphane Laurent <[email protected]>
License: GPL (>= 2)
Version: 2.1.1
Built: 2024-11-06 03:10:14 UTC
Source: https://github.com/stla/jsonstrings

Help Index

R6 class to represent a JSON string

Description

R6 class to represent a JSON string.

Active bindings

prettyPrint

get or set the value of prettyPrint

Methods

Public methods

Method new()

Creates a new jsonString object.

Usage
jsonString$new(string)
Arguments
string

a string representing a JSON object, or the path to a JSON file

Returns

A jsonString object.

Examples
jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$prettyPrint
jstring
jstring$prettyPrint <- FALSE
jstring

jstring <- "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
jsonString$new(jstring)

Method print()

Print a jsonString object.

Usage
jsonString$print(...)
Arguments
...

ignored

Examples
jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring
jstring$prettyPrint <- FALSE
jstring

Method asString()

Converts a jsonString to a character string.

Usage
jsonString$asString(pretty = FALSE)
Arguments
pretty

Boolean, whether to get a pretty string

Returns

A string.

Examples
jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
cat(jstring$asString())
cat(jstring$asString(pretty = TRUE))

Method at()

Extract an element in a JSON string by giving a path of keys or indices.

Usage
jsonString$at(...)
Arguments
...

the elements forming the path, integers or strings; an integer represents an index in an array (starting at 0), a string represents a key in an object

Returns

A jsonString object.

Examples
jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$at(1)
jstring$at(2, "x")

Method hasKey()

Checks whether a key exists in the reference JSON string.

Usage
jsonString$hasKey(key)
Arguments
key

a string

Returns

A Boolean value.

Examples
jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$hasKey("x")
jstring <- jsonString$new(
  "{\"x\": [2,3,4], \"y\": 42}"
)
jstring$hasKey("x")

Method keys()

Get the keys of the reference JSON string (if it represents an object).

Usage
jsonString$keys()
Returns

A character vector.

Examples
jstring <- jsonString$new(
  "{\"x\": [2,3,4], \"y\": 42}"
)
jstring$keys()

Method addProperty()

Add a new property to the reference JSON string (if it represents an object).

Usage
jsonString$addProperty(key, value)
Arguments
key

a character string, the key of the new property

value

a JSON string, either a jsonString object or a string

Returns

This updates the reference JSON string and this returns it invisibly.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
ppty <- jsonString$new("[9, 99]")
jstring$addProperty("c", ppty)
jstring
jstring$addProperty("d", "null")
jstring

Method erase()

Erase an object property or an array element from the reference JSON string.

Usage
jsonString$erase(at)
Arguments
at

either a character string, the key of the property to be erased, or an integer, the index of the array element to be erased

Returns

This invisibly returns the updated reference JSON string.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$erase("b")
jstring
jstring <- jsonString$new("[1, 2, 3, 4, 5]")
jstring$erase(2)
jstring

Method size()

Number of elements in the reference JSON string.

Usage
jsonString$size()
Returns

An integer.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$size()

Method update()

Update the reference JSON string (if it represents an object).

Usage
jsonString$update(jstring)
Arguments
jstring

a JSON string representing an object, either a jsonString object or a string

Returns

This invisibly returns the updated reference JSON string.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring2 <- "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
jstring$update(jstring2)
jstring

Method merge()

Merge the reference JSON string (if it represents an object).

Usage
jsonString$merge(jstring)
Arguments
jstring

a JSON string, either a jsonString object or a string representing a JSON object

Returns

This invisibly returns the updated reference JSON string.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring2 <- "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
jstring$merge(jstring2)
jstring

Method patch()

Apply a JSON patch to the reference JSON string (if it represents an array or an object).

Usage
jsonString$patch(jspatch)
Arguments
jspatch

a JSON patch, a JSON string representing an array (see the link in details); it could be either a jsonString object or a string

Details

See jsonpatch.com.

Returns

A new jsonString object.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jspatch <- "[
  {\"op\": \"remove\", \"path\": \"/a\"},
  {\"op\": \"replace\", \"path\": \"/b\", \"value\": null}
]"
jstring$patch(jspatch)

Method push()

Append an element to the reference JSON string (if it represents an array).

Usage
jsonString$push(jstring)
Arguments
jstring

a JSON string, either a jsonString object or a string representing a JSON object

Returns

This invisibly returns the updated reference JSON string.

Examples
jstring <- jsonString$new("[1, 2, 3, 4, 5]")
jstring2 <- jsonString$new(
  "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
 )
jstring$push(jstring2)
jstring

Method is()

Check the type of the reference JSON string.

Usage
jsonString$is(type)
Arguments
type

the type to be checked, one of "array", "object", "string", "number", "integer", "float", "null", "boolean"

Returns

A Boolean value.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$is("object")
jstring$is("array")
jstring <- jsonString$new("999")
jstring$is("integer")
jstring$is("number")
jstring$is("float")

Method type()

Get the type of the reference JSON string.

Usage
jsonString$type()
Returns

A character string indicating the type of the JSON string.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$type()
jstring <- jsonString$new("999")
jstring$type()

Method flatten()

Flatten the reference JSON string.

Usage
jsonString$flatten()
Returns

A new jsonString object.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":{\"x\":\"hello\",\"y\":\"hi\"}}"
)
jstring$flatten()

Method unflatten()

Unflatten the reference JSON string (if it is flattened).

Usage
jsonString$unflatten()
Returns

A new jsonString object.

Examples
folder <- system.file(package = "jsonStrings")
files <- list.files(folder, recursive = TRUE)
sizes <- file.size(file.path(folder, files))
files <- sprintf('"%s"', paste0("/", files))
string <- sprintf("{%s}", paste0(files, ":", sizes, collapse = ","))
jstring <- jsonString$new(string)
jstring$unflatten()

Method writeFile()

Write the reference JSON string to a file.

Usage
jsonString$writeFile(filename)
Arguments
filename

name of the file

Returns

Nothing.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jsonfile <- tempfile(fileext = ".json")
jstring$writeFile(jsonfile)
cat(readLines(jsonfile), sep = "\n")
jsonString$new(jsonfile)

Method copy()

Copy the reference JSON string.

Usage
jsonString$copy()
Returns

A new jsonString object.

Examples
jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
copy <- jstring$copy()
copy$erase("b")
jstring
naive_copy <- jstring
naive_copy$erase("b")
jstring

Examples

## ------------------------------------------------
## Method `jsonString$new`
## ------------------------------------------------

jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$prettyPrint
jstring
jstring$prettyPrint <- FALSE
jstring
jstring <- "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
jsonString$new(jstring)

## ------------------------------------------------
## Method `jsonString$print`
## ------------------------------------------------

jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring
jstring$prettyPrint <- FALSE
jstring

## ------------------------------------------------
## Method `jsonString$asString`
## ------------------------------------------------

jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
cat(jstring$asString())
cat(jstring$asString(pretty = TRUE))

## ------------------------------------------------
## Method `jsonString$at`
## ------------------------------------------------

jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$at(1)
jstring$at(2, "x")

## ------------------------------------------------
## Method `jsonString$hasKey`
## ------------------------------------------------

jstring <- jsonString$new(
  "[1, [\"a\", 99], {\"x\": [2,3,4], \"y\": 42}]"
)
jstring$hasKey("x")
jstring <- jsonString$new(
  "{\"x\": [2,3,4], \"y\": 42}"
)
jstring$hasKey("x")

## ------------------------------------------------
## Method `jsonString$keys`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"x\": [2,3,4], \"y\": 42}"
)
jstring$keys()

## ------------------------------------------------
## Method `jsonString$addProperty`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
ppty <- jsonString$new("[9, 99]")
jstring$addProperty("c", ppty)
jstring
jstring$addProperty("d", "null")
jstring

## ------------------------------------------------
## Method `jsonString$erase`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$erase("b")
jstring
jstring <- jsonString$new("[1, 2, 3, 4, 5]")
jstring$erase(2)
jstring

## ------------------------------------------------
## Method `jsonString$size`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$size()

## ------------------------------------------------
## Method `jsonString$update`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring2 <- "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
jstring$update(jstring2)
jstring

## ------------------------------------------------
## Method `jsonString$merge`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring2 <- "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
jstring$merge(jstring2)
jstring

## ------------------------------------------------
## Method `jsonString$patch`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jspatch <- "[
  {\"op\": \"remove\", \"path\": \"/a\"},
  {\"op\": \"replace\", \"path\": \"/b\", \"value\": null}
]"
jstring$patch(jspatch)

## ------------------------------------------------
## Method `jsonString$push`
## ------------------------------------------------

jstring <- jsonString$new("[1, 2, 3, 4, 5]")
jstring2 <- jsonString$new(
  "{\"a\":[4,5,6],\"c\":\"goodbye\"}"
 )
jstring$push(jstring2)
jstring

## ------------------------------------------------
## Method `jsonString$is`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$is("object")
jstring$is("array")
jstring <- jsonString$new("999")
jstring$is("integer")
jstring$is("number")
jstring$is("float")

## ------------------------------------------------
## Method `jsonString$type`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jstring$type()
jstring <- jsonString$new("999")
jstring$type()

## ------------------------------------------------
## Method `jsonString$flatten`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":{\"x\":\"hello\",\"y\":\"hi\"}}"
)
jstring$flatten()

## ------------------------------------------------
## Method `jsonString$unflatten`
## ------------------------------------------------

folder <- system.file(package = "jsonStrings")
files <- list.files(folder, recursive = TRUE)
sizes <- file.size(file.path(folder, files))
files <- sprintf('"%s"', paste0("/", files))
string <- sprintf("{%s}", paste0(files, ":", sizes, collapse = ","))
jstring <- jsonString$new(string)
jstring$unflatten()

## ------------------------------------------------
## Method `jsonString$writeFile`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
jsonfile <- tempfile(fileext = ".json")
jstring$writeFile(jsonfile)
cat(readLines(jsonfile), sep = "\n")
jsonString$new(jsonfile)

## ------------------------------------------------
## Method `jsonString$copy`
## ------------------------------------------------

jstring <- jsonString$new(
  "{\"a\":[1,2,3],\"b\":\"hello\"}"
)
copy <- jstring$copy()
copy$erase("b")
jstring
naive_copy <- jstring
naive_copy$erase("b")
jstring