Answers from a file¶

--answers-from <path> supplies answers from a TOML, JSON or YAML file, on both git tpl init and git tpl update.

$ git tpl init https://github.com/noirbizarre/rust-library-template \
    --answers-from answers.toml

It exists because four unrelated things need the same thing:

• migrating from Copier, Cruft, or anything else that recorded its answers
• creating many projects from one set of house values
• rendering in CI, where there is no terminal to prompt at
• checking a template's fixtures in, so the template can have tests

A tool-specific importer would have bought only the first, and would have put someone else's file format in the CLI surface permanently.

The file¶

Either a flat table of name = value:

project_name = "my-thing"
license = "Apache-2.0"
with_ci = true
port = 8080

…or those same pairs under an answers key, so a template's fixture file can carry other tables beside them:

[answers]
project_name = "my-thing"

[expect]
files = ["pyproject.toml"]

Nothing else is a valid shape. A document that is not a table is refused (tpl::answers::shape) rather than silently supplying nothing.

Formats¶

The same three the data sources take, read by the same parsers, chosen by the file extension:

YAML matters here specifically: .copier-answers.yml and most hand-written house-defaults files are YAML, and requiring a yq step first would have undercut the point of the flag. It is YAML 1.2, so no is the string "no" — see About YAML.

Types are preserved¶

This is the difference between the file and --answer. A flag can only carry text, so --answer port=8080 is a string that the question's declared type turns into an integer. A file carries the type it was written with.

A value that does not match the question's declared type is an error (tpl::eval::wrong_type), never a silent coercion. port = "eighty" for an integer question fails; it does not become 0.

Unknown keys are ignored, and reported¶

A key naming no question in the template is skipped, and named on stderr:

warning: answers ignored: they name no question in this template
  _src_path
  _commit

Both halves are deliberate. Erroring would make the flag useless for the case that motivated it — a .copier-answers.yml carries _src_path and _commit, and any long-lived template has dropped a question at some point. Staying silent would make a typo'd key look exactly like an answer that had no effect.

Nothing about the ignored keys is recorded: .config/git.tpl.toml holds the answers to questions the template actually asked.

A Copier answers file works unedited¶

$ git tpl init https://github.com/example/rust-library \
    --answers-from .copier-answers.yml

This is not Copier compatibility, and is not meant to grow into it. The flag maps names to names: a template whose questions were renamed between tools needs its answers edited. Shipping a mapping language to avoid that would cost more than the editing does.

Precedence¶

--answers-from is repeatable, and later files win over earlier ones — house defaults first, the specific file on top:

$ git tpl init <template> \
    --answers-from house-defaults.toml \
    --answers-from this-project.toml \
    --answer project_name=thing

The whole chain, highest first:

--answer
  >  the last --answers-from
  >  earlier --answers-from
  >  answers recorded in .config/git.tpl.toml   (update only)
  >  the question's default

A question covered by none of them is asked as usual, unless --defaults or tpl.interactive false is in force — in which case its default is taken, and a question with no default is an error (tpl::eval::unanswered).

Failures¶

The path is resolved relative to your working directory, and is used as given. It is deliberately not restricted to the project — you named it yourself, unlike a local data source path, which comes out of a template repository and is therefore untrusted input.