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pypyr.parser.jsonfile permalink

read json file into context permalink

Takes a path from the cli input argument, and read the json file at that path into context. Strongly typed values in the source json will translate into the pipeline context. This lets you initialize pipeline context from a json file.

The input path can be relative or absolute. Relative paths are relative to the current working directory.

example permalink

Given a json file like this, saved as ./sample-files/sample.json:

{
    "key1": "value1",
    "key2": "value2",
    "key3": "value3 and {key1} and {key2}",
    "echoMe": "this is a value from a json file",
    "keyInt": 123,
    "keyBool": true
}

And given a pipeline like this, arbitrarily saved as ./jsonfile-parser.yaml:

# ./jsonfile-parser.yaml
context_parser: pypyr.parser.jsonfile
steps:
  # echoMe is set in the json input file
  - pypyr.steps.echo
  - name: pypyr.steps.set
    comment: use the int as a strongly typed int
    in:
      set:
        intResult: !py keyInt * 2
  
  - name: pypyr.steps.echo
    comment: formatting expressions in json file will work
    in:
      echoMe: '{key3}'
  
  - name: pypyr.steps.echo
    comment: print out result of int calculation
    in:
      echoMe: "strongly typed happens automatically: {intResult}"
  
  - name: pypyr.steps.echo
    comment: only run if input bool is true
    run: '{keyBool}'
    in:
      echoMe: you'll only see me if the bool was true

You can run this pipeline as follows:

$ pypyr jsonfile-parser ./sample-files/sample.json
this is a value from a json file
value3 and value1 and value2
strongly typed happens automatically: 246
you'll only see me if the bool was true

If you change the keyBool bool to false:

$ pypyr jsonfile-parser ./sample-files/sample.json
this is a value from a json file
value3 and value1 and value2
strongly typed happens automatically: 246

json structure permalink

The top root level json should not be an Array [], but rather an Object {}.

Array (this won’t work):

[
  "eggs",
  "ham"
]

Instead, do an Object:

{
  "breakfastOfChampions": [
    "eggs",
    "ham"
  ]
}

spaces in file path permalink

Depending on your O/S, shell and file-system, it’s up to you to deal with special characters in the file-name.

Taking MacOS as an example, all of the following will work:

$ pypyr mypipeline ./testfiles/sample.json
$ pypyr mypipeline ./test files/sample with space.json
$ pypyr mypipeline "./test files/sample with space.json"
$ pypyr mypipeline ./"test files"/"sample with space.json"

encoding permalink

By default the json file will read in the platform’s default encoding. This is utf-8 for most systems, but be aware on Windows it’s still cp1252.

See here for more details on handling text encoding in pypyr and changing the defaults.

see also

last updated on .