jsonString {jsonStrings}

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

• jsonString$new()

• jsonString$print()

• jsonString$asString()

• jsonString$at()

• jsonString$hasKey()

• jsonString$keys()

• jsonString$addProperty()

• jsonString$erase()

• jsonString$size()

• jsonString$update()

• jsonString$merge()

• jsonString$patch()

• jsonString$push()

• jsonString$is()

• jsonString$type()

• jsonString$flatten()

• jsonString$unflatten()

• jsonString$writeFile()

• jsonString$copy()

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