In chiefBiiko/jsonmatch: Match JSON

knitr::opts_chunk$set(echo = TRUE, comment=NA)

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Simple JSON matching.

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Get it

devtools::install_github('chiefBiiko/jsonmatch')

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Usage

jsonmatch::jsonmatch(json, pattern, auto_unbox=FALSE, strict=TRUE)

• json character. In-memory JSON string or filename. required
• pattern character. Subset pattern. required
• auto_unbox logical. Unbox JSON? Default: FALSE. optional
• strict logical. Only allow valid JSON? Default: TRUE. optional

Return character, json. JSON subset.

pattern allows matching keys of JSON arrays and objects. Its syntax rules are simple:

• Array values are referenced via their index (zero-based): [0] or [1,3] or [2:] or [2:3]
• Object values are referenced via their key: .key or .k*y or .*y or .k* or .*
• Multiple subset paths are separated by a comma: .keyA[0],.keyB[0]

Note that a colon within an array subset pattern is only valid if it is trailing, indicating to select all array elements with an index in the range of [low:] to length(array) - 1 aka the end of the array. The wildcard character in an object subset pattern matches any alphanumeric character sequence. Wildcard matching cannot be used if object keys contain non-alphanumeric characters [^[:alnum:]].

For the rationale of auto_unbox check out boxjson. If strict is TRUE and jsonlite::validate(json) evaluates to FALSE an error is thrown.

# some JSON
some.json <- jsonlite::toJSON(list(list(name='herman', gang='almans'), 
                                   list(name='habibo', gang=c('haji', '419'))))

# peek at it
cat('some JSON:\n', some.json, sep='')

# who u with
gangs <- jsonmatch::jsonmatch(some.json, '[0:].gang')
cat('gangs:\n', gangs, sep='')

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TODO

• elaborate tests

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License

MIT

chiefBiiko/jsonmatch documentation built on May 23, 2019, 8:36 a.m.