Troubleshooting

No file was generated

Constago only writes a package file when at least one selected struct produces output.

Check:

1. input.dir is relative to the process working directory.
2. At least one input.include pattern matches a .go file.
3. No exclusion removes the file or package.
4. Struct and field explicit mode is not filtering everything.
5. At least one element has a usable value, or a getter can be produced.

Run with details:

constago --verbose 2 --config constago.yaml

A tagged field is missing

With input.mode: tag, the field produces no value when none of the configured tags exists or when the selected tag value is empty.

Use tagThenField to fall back to the Go field name:

input:
  mode: "tagThenField"
  tag_priority: ["json"]

field in tag priority did not use the Go field name

Inside tag_priority, field means a literal struct tag named field. To always use the Go field name, select field mode:

input:
  mode: "field"
  tag_priority: ["field"]

To prefer a tag and fall back to the Go field name, use tagThenField:

input:
  mode: "tagThenField"
  tag_priority: ["json"]

JSON - appeared in generated output

Constago reads tag text rather than interpreting encoding/json rules. Exclude the field explicitly:

Secret string `json:"-" constago:"exclude"`

Generated code does not compile

Run:

gofmt -w .
go test ./...

Common causes include:

• A generated identifier collides with existing code.
• Two element or getter configurations produce the same name.
• A camel or snake name is inaccessible from another package.
• A field type refers to code unavailable under the active build tags.
• An old generated file is still present under a different filename.

Constago writes syntactically structured Go but does not run gofmt or the Go compiler itself.

Configuration validation failed

Check that:

• File globs end in .go.
• Package selectors use package:ValidGoIdentifier.
• Output filenames end in .go and contain no directory separator.
• Every element and getter has a valid Go identifier name.
• Every getter return names an element or is exactly :value.
• Regex values compile.
• Enum strings match the casing shown in Configuration.