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textrude_convenience.md

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Textrude convenience commands for working with files

The render command provides the most powerful way of applying templates to arbitrary sets of inputs and outputs as described here but Textrude also supplies some commands that make it easy to apply simple Scriban expressions to files as "one-liners".

All commands have the same basic parameter set:

  • -i, --input : an input file or stdin if omitted
  • -o, --output : an output file or stdout if omitted
  • -e, --expression : a Scriban expression
  • -f, --format : specifies the format of the data. If this is omitted, textrude will try to guess the format, first by looking at the file extension (if a filename was used) and then by examining the first few hundred characters of the input.

All the Scriban built-in methods are imported to allow for terser expressions; ie contains may be used instead of string.contains.

'i' commands

The i commands assume that the input is an array of items. I.e. Json array, Yaml array, CSV file or text file (which is treated as an array of lines)

The expression is applied to each item in turn, with the current item being referred to as i.

iFilter

Returns only the items that match the filter.
Examples:

# perform a search on items
textrude iFilter -e "(i.Population >100) && (contains i.Country 'United')"

iDo

Mutates each item in turn and returns the input set

Examples:

# create a new column/property from two others 
textrude iDo -e "i.productivity= i.gdp/i.population"

# remove a column/property
textrude iDo -e "i.unwanted=null"

iMap

Creates a new item in place of the old item returns the mapped set

Examples:

#create a new set of records, each with an 'id' and 'name' property derived from the input
textrude iMap -e "id: i.id, name: (i.first+i.last) "

'm' commands

The m commands operate on the model. In contrast to the i commands, they do not automatically return a serialised representation of the model because it's not normally useful. However you can use a pipe to one of the format conversion commands if you want.

mDo

Pipes the model into the expression and returns the result.

Examples:

# return the number of items in the input.  Note that "array.size" is fully qualifed
# because the string.size method would otherwise take preference
textrude mDo -e "array.size"

Do

Returns the result of the expression. The input model is referred to as 'm'

Examples

# remove an unwanted property and return the JSON representation
textrude Do -e "m.additional_info=null;to_json"

# print out the size of the Yaml represention vs the size of the JSON representation
textrude Do -e "'Yaml:'+ (m|to_yaml|size) +' Json:'+(to_json|size)"