yq/pkg/yqlib/doc/usage/toml.md
Copilot 2927a28283
TOML encoder: prefer readable table sections over inline tables (#2649)
* Initial plan

* Fix TOML encoder to prefer readable table sections over inline tables

When converting from YAML/JSON to TOML, the encoder now always uses
readable TOML table section syntax ([section]) instead of compact inline
hash table syntax (key = { ... }), which better matches TOML's goal as
a human-focused configuration format.

Changes:
- decoder_toml.go: Mark inline TOML tables with FlowStyle so round-trips
  can be distinguished from YAML flow mappings
- encoder_toml.go:
  - encodeTopLevelEntry: use FlowStyle check instead of EncodeSeparate to
    decide inline vs table section (all block mappings now become tables)
  - encodeSeparateMapping: count FlowStyle children as attributes; use
    recursive encodeSeparateMapping for nested non-flow mappings
  - encodeMappingBodyWithPath: emit non-flow child mappings as sub-table
    sections instead of inline tables
- toml_test.go: add encode (YAML→TOML) test scenarios, update roundtrip
  expectations for inline tables (now expanded to table sections)

Agent-Logs-Url: https://github.com/mikefarah/yq/sessions/4824a219-6d5e-42e7-bca1-a8a277bf8c6a

Co-authored-by: mikefarah <1151925+mikefarah@users.noreply.github.com>

* Fix TOML roundtrip: use TomlInline flag instead of FlowStyle to preserve inline tables

FlowStyle affected YAML decode output (causing inline tables to appear as
YAML flow mappings). Replace it with a new TOML-specific TomlInline bool
on CandidateNode that:
- Is set by the TOML decoder for inline tables (not FlowStyle)
- Is copied by UpdateAttributesFrom so it survives DeeplyAssign merges
- Is checked by the TOML encoder alongside FlowStyle (for YAML flow maps)
- Has no effect on the YAML encoder, preserving existing TOML→YAML output

TOML roundtrip tests are restored to their original expected values (inline
tables stay inline, table sections stay as sections).

Agent-Logs-Url: https://github.com/mikefarah/yq/sessions/f59bdf62-6d16-4664-991b-38eb87c9d81c

Co-authored-by: mikefarah <1151925+mikefarah@users.noreply.github.com>

* Refactor EncodeSeparate+TomlInline into a single EncodeHint enum

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Co-authored-by: mikefarah <1151925+mikefarah@users.noreply.github.com>

* Fix stale comment in hasStructuralChildren

Agent-Logs-Url: https://github.com/mikefarah/yq/sessions/24db9a8f-601d-4ccf-ada7-129ed3226bb6

Co-authored-by: mikefarah <1151925+mikefarah@users.noreply.github.com>

* Remove unused hasStructuralChildren method from tomlEncoder

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---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mikefarah <1151925+mikefarah@users.noreply.github.com>
2026-04-12 18:36:43 +10:00

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Markdown

# TOML
Decode from TOML. Note that `yq` does not yet support outputting in TOML format (and therefore it cannot roundtrip)
## Parse: Simple
Given a sample.toml file of:
```toml
A = "hello"
B = 12
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
A: hello
B: 12
```
## Parse: Deep paths
Given a sample.toml file of:
```toml
person.name = "hello"
person.address = "12 cat st"
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
person:
name: hello
address: 12 cat st
```
## Encode: Scalar
Given a sample.toml file of:
```toml
person.name = "hello"
person.address = "12 cat st"
```
then
```bash
yq '.person.name' sample.toml
```
will output
```yaml
hello
```
## Parse: inline table
Given a sample.toml file of:
```toml
name = { first = "Tom", last = "Preston-Werner" }
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
name:
first: Tom
last: Preston-Werner
```
## Parse: Array Table
Given a sample.toml file of:
```toml
[owner.contact]
name = "Tom Preston-Werner"
age = 36
[[owner.addresses]]
street = "first street"
suburb = "ok"
[[owner.addresses]]
street = "second street"
suburb = "nice"
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
owner:
contact:
name: Tom Preston-Werner
age: 36
addresses:
- street: first street
suburb: ok
- street: second street
suburb: nice
```
## Parse: Array of Array Table
Given a sample.toml file of:
```toml
[[fruits]]
name = "apple"
[[fruits.varieties]] # nested array of tables
name = "red delicious"
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
fruits:
- name: apple
varieties:
- name: red delicious
```
## Parse: Empty Table
Given a sample.toml file of:
```toml
[dependencies]
```
then
```bash
yq -oy '.' sample.toml
```
will output
```yaml
dependencies: {}
```
## Roundtrip: inline table attribute
Given a sample.toml file of:
```toml
name = { first = "Tom", last = "Preston-Werner" }
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
name = { first = "Tom", last = "Preston-Werner" }
```
## Roundtrip: table section
Given a sample.toml file of:
```toml
[owner.contact]
name = "Tom"
age = 36
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
[owner.contact]
name = "Tom"
age = 36
```
## Roundtrip: array of tables
Given a sample.toml file of:
```toml
[[fruits]]
name = "apple"
[[fruits.varieties]]
name = "red delicious"
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
[[fruits]]
name = "apple"
[[fruits.varieties]]
name = "red delicious"
```
## Roundtrip: arrays and scalars
Given a sample.toml file of:
```toml
A = ["hello", ["world", "again"]]
B = 12
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
A = ["hello", ["world", "again"]]
B = 12
```
## Roundtrip: simple
Given a sample.toml file of:
```toml
A = "hello"
B = 12
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
A = "hello"
B = 12
```
## Roundtrip: deep paths
Given a sample.toml file of:
```toml
[person]
name = "hello"
address = "12 cat st"
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
[person]
name = "hello"
address = "12 cat st"
```
## Roundtrip: empty array
Given a sample.toml file of:
```toml
A = []
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
A = []
```
## Roundtrip: sample table
Given a sample.toml file of:
```toml
var = "x"
[owner.contact]
name = "Tom Preston-Werner"
age = 36
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
var = "x"
[owner.contact]
name = "Tom Preston-Werner"
age = 36
```
## Roundtrip: empty table
Given a sample.toml file of:
```toml
[dependencies]
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
[dependencies]
```
## Roundtrip: comments
Given a sample.toml file of:
```toml
# This is a comment
A = "hello" # inline comment
B = 12
# Table comment
[person]
name = "Tom" # name comment
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
# This is a comment
A = "hello" # inline comment
B = 12
# Table comment
[person]
name = "Tom" # name comment
```
## Roundtrip: sample from web
Given a sample.toml file of:
```toml
# This is a TOML document
title = "TOML Example"
[owner]
name = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00-08:00
[database]
enabled = true
ports = [8000, 8001, 8002]
data = [["delta", "phi"], [3.14]]
temp_targets = { cpu = 79.5, case = 72.0 }
# [servers] yq can't do this one yet
[servers.alpha]
ip = "10.0.0.1"
role = "frontend"
[servers.beta]
ip = "10.0.0.2"
role = "backend"
```
then
```bash
yq '.' sample.toml
```
will output
```yaml
# This is a TOML document
title = "TOML Example"
[owner]
name = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00-08:00
[database]
enabled = true
ports = [8000, 8001, 8002]
data = [["delta", "phi"], [3.14]]
temp_targets = { cpu = 79.5, case = 72.0 }
# [servers] yq can't do this one yet
[servers.alpha]
ip = "10.0.0.1"
role = "frontend"
[servers.beta]
ip = "10.0.0.2"
role = "backend"
```
## Encode: Simple mapping produces table section
Given a sample.yml file of:
```yaml
arg:
hello: foo
```
then
```bash
yq -o toml '.' sample.yml
```
will output
```toml
[arg]
hello = "foo"
```