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bazel-lib/lib/jq.bzl
2023-04-19 09:03:52 -07:00

139 lines
4.1 KiB
Python

"""Public API for jq"""
load("//lib/private:jq.bzl", _jq_lib = "jq_lib")
_jq_rule = rule(
attrs = _jq_lib.attrs,
implementation = _jq_lib.implementation,
toolchains = ["@aspect_bazel_lib//lib:jq_toolchain_type"],
)
def jq(name, srcs, filter = None, filter_file = None, args = [], out = None, **kwargs):
"""Invoke jq with a filter on a set of json input files.
For jq documentation, see https://stedolan.github.io/jq/.
To use this rule you must register the jq toolchain in your WORKSPACE:
```starlark
load("@aspect_bazel_lib//lib:repositories.bzl", "register_jq_toolchains")
register_jq_toolchains()
```
Usage examples:
```starlark
load("@aspect_bazel_lib//lib:jq.bzl", "jq")
# Create a new file bazel-out/.../no_srcs.json
jq(
name = "no_srcs",
srcs = [],
filter = ".name = \"Alice\"",
)
# Remove fields from package.json.
# Writes to bazel-out/.../package.json which means you must refer to this as ":no_dev_deps"
# since Bazel doesn't allow a label for the output file that collides with the input file.
jq(
name = "no_dev_deps",
srcs = ["package.json"],
filter = "del(.devDependencies)",
)
# Merge bar.json on top of foo.json, producing foobar.json
jq(
name = "merged",
srcs = ["foo.json", "bar.json"],
filter = ".[0] * .[1]",
args = ["--slurp"],
out = "foobar.json",
)
# Long filters can be split over several lines with comments
jq(
name = "complex",
srcs = ["a.json", "b.json"],
filter = \"\"\"
.[0] as $a
# Take select fields from b.json
| (.[1] | {foo, bar, tags}) as $b
# Merge b onto a
| ($a * $b)
# Combine 'tags' array from both
| .tags = ($a.tags + $b.tags)
# Add new field
+ {\\\"aspect_is_cool\\\": true}
\"\"\",
args = ["--slurp"],
)
# Load filter from a file
jq(
name = "merged",
srcs = ["foo.json", "bar.json"],
filter_file = "filter.txt",
args = ["--slurp"],
out = "foobar.json",
)
# Convert genquery output to json
genquery(
name = "deps",
expression = "deps(//some:target)",
scope = ["//some:target"],
)
jq(
name = "deps_json",
srcs = [":deps"],
args = [
"--raw-input",
"--slurp",
],
filter = "{ deps: split(\"\\n\") | map(select(. | length > 0)) }",
)
# With --stamp, causes properties to be replaced by version control info.
jq(
name = "stamped",
srcs = ["package.json"],
filter = "|".join([
# Don't directly reference $STAMP as it's only set when stamping
# This 'as' syntax results in $stamp being null in unstamped builds.
"$ARGS.named.STAMP as $stamp",
# Provide a default using the "alternative operator" in case $stamp is null.
".version = ($stamp.BUILD_EMBED_LABEL // \"<unstamped>\")",
]),
)
```
Args:
name: Name of the rule
srcs: List of input files. May be empty.
filter: Filter expression (https://stedolan.github.io/jq/manual/#Basicfilters).
Subject to stamp variable replacements, see [Stamping](./stamping.md).
When stamping is enabled, a variable named "STAMP" will be available in the filter.
Be careful to write the filter so that it handles unstamped builds, as in the example above.
filter_file: File containing filter expression (alternative to `filter`)
args: Additional args to pass to jq
out: Name of the output json file; defaults to the rule name plus ".json"
**kwargs: Other common named parameters such as `tags` or `visibility`
"""
default_name = name + ".json"
if not out and not default_name in srcs:
out = default_name
_jq_rule(
name = name,
srcs = srcs,
filter = filter,
filter_file = filter_file,
args = args,
out = out,
**kwargs
)