pypyr.steps.fileformatyaml permalink

find & replace tokens in yaml file permalink

Parses input yaml file and substitutes {tokens} from the pypyr context.

Pretty much does the same thing as pypyr.steps.fileformat, only it makes it easier to work with curly braces for substitutions without tripping over the yaml’s structural braces.

If your yaml doesn’t use curly braces that aren’t meant for {token} substitutions, you can happily use pypyr.steps.fileformat instead - it’s more memory efficient.

This step does not preserve comments. Use fileformat if you need to preserve comments on output.

Given input yaml like this:

k1: v1
  k2.1: v2.1
    - 2.2.1,
    - START {replaceMeNested} END
k3: "{replaceMeString}"
k4: "{replaceMeInt}"
k5: "{replaceMeBool}"
"{replaceMeKey}": "this will replace the key"

And a pipeline like this:

  - name: pypyr.steps.fileformatyaml
    comment: read a yaml from disk, do some substitutions, write back out.
      replaceMeString: this was replaced by pypyr
      replaceMeInt: 420
      replaceMeBool: false
      replaceMeNested: doesn't matter where you are in the nesting structure
      replaceMeKey: keyfrompypyr
          in: ./sample-files/sample.yaml
          out: ./out/

The formatted output yaml file will be:

k1: v1
  k2.1: v2.1
    - 2.2.1,
    - START doesn't matter where you are in the nesting structure END
k3: this was replaced by pypyr
k4: 420
k5: false
keyfrompypyr: this will replace the key

type-safe token replacement permalink

Notice that you can replace values in the yaml document and keep the correct type - so numbers are numbers, booleans are booleans and so forth.

Even though you always have to set the "{replacement_expression}" inside quotes in the source yaml to ensure valid yaml, pypyr will output the correct type based on the value to which the expression evaluates.

You can also use replacement expressions in the yaml document’s keys.

multiple files & globs permalink

fileformatyaml expects the following context keys:

  • fileFormatYaml
    • in
      • Mandatory path(s) to source file on disk.
      • This can be a string path to a single file, or a glob, or a list of paths and globs.
      • Each path can be a glob, a relative or absolute path.
    • out (optional)
      • Write output file to here. Will create directories in path if these do not exist already.

See file format settings for more examples on in/out path handling - the same processing rules apply.

Example with a glob input and a normal path in a list:

  in: [./file1.yaml, ./testfiles/sub3/**/*.yaml]
  # note the dir separator at the end.
  # since >1 in files, out can only be a dir.
  out: ./out/replace/

If you do not specify out, it will over-write (i.e in-place edit) all the files specified by in.

The file in and out paths support substitutions, which allows you to specify paths dynamically.

See a worked example of fileformatyaml.

see also

last updated on .