OpenSearch/docs
Nik Everett d03b8e4abb Implement reading from null safe dereferences
Null safe dereferences make handling null or missing values shorter.
Compare without:
```
if (ctx._source.missing != null && ctx._source.missing.foo != null) {
  ctx._source.foo_length = ctx.source.missing.foo.length()
}
```

To with:
```
Integer length = ctx._source.missing?.foo?.length();
if (length != null) {
  ctx._source.foo_length = length
}
```

Combining this with the as of yet unimplemented elvis operator allows
for very concise defaults for nulls:
```
ctx._source.foo_length = ctx._source.missing?.foo?.length() ?: 0;
```

Since you have to start somewhere, we started with null safe dereferenes.

Anyway, this is a feature borrowed from groovy. Groovy allows writing to
null values like:
```
def v = null
v?.field = 'cat'
```
And the writes are simply ignored. Painless doesn't support this at this
point because it'd be complex to implement and maybe not all that useful.

There is no runtime cost for this feature if it is not used. When it is
used we implement it fairly efficiently, adding a jump rather than a
temporary variable.

This should also work fairly well with doc values.
2016-11-09 07:20:11 -05:00
..
community-clients Add elasticsearcher for PHP (#21143) 2016-11-04 17:27:31 +01:00
groovy-api Fix version constant in Groovy API docs 2016-11-08 08:08:45 -05:00
java-api Documentation updates for scroll API size parameter (#21229) 2016-11-01 15:55:09 -04:00
java-rest Rest client: don't reuse that same HttpAsyncResponseConsumer across multiple retries (#21378) 2016-11-08 16:42:42 +01:00
perl Updated copyright years to include 2016 (#17808) 2016-04-18 12:39:23 +02:00
plugins Docs: Update discovery plugins example configuration with discovery.zen.hosts_provider (#21390) 2016-11-07 13:33:08 -08:00
python Remove most of the need for `// NOTCONSOLE` 2016-09-06 10:32:54 -04:00
reference Implement reading from null safe dereferences 2016-11-09 07:20:11 -05:00
resiliency Update resiliency page for the release of v5 (#21177) 2016-10-28 18:46:54 +02:00
ruby Updated copyright years to include 2016 (#17808) 2016-04-18 12:39:23 +02:00
src/test Test: Remove multi process support from rest test runner (#21391) 2016-11-07 15:07:34 -08:00
README.asciidoc Document how to run a single docs test 2016-10-06 21:10:49 +02:00
build.gradle Make it clear _suggest doesn't support source filtering (#21268) 2016-11-06 20:15:45 -05:00

README.asciidoc

The Elasticsearch docs are in AsciiDoc format and can be built using the
Elasticsearch documentation build process.

See: https://github.com/elastic/docs

Snippets marked with `// CONSOLE` are automatically annotated with "VIEW IN
SENSE" in the documentation and are automatically tested by the command
`gradle :docs:check`. To test just the docs from a single page, use e.g.
`gradle :docs:check -Dtest.method=*rollover*`.

By default `// CONSOLE` snippet runs as its own isolated
test. You can manipulate the test execution in the following ways:

* `// TEST`: Explicitly marks a snippet as a test. Snippets marked this way
are tests even if they don't have `// CONSOLE`.
  * `// TEST[s/foo/bar/]`: Replace `foo` with `bar` in the test. This should be
  used sparingly because it makes the test "lie". Sometimes, though, you can use
  it to make the tests more clear.
  * `// TEST[catch:foo]`: Used to expect errors in the requests. Replace `foo`
  with `request` to expect a 400 error, for example. If the snippet contains
  multiple requests then only the last request will expect the error.
  * `// TEST[continued]`: Continue the test started in the last snippet. Between
  tests the nodes are cleaned: indexes are removed, etc. This will prevent that.
  This is really useful when you have text and snippets that work together to
  tell the story of some use case because it merges the snippets (and thus the
  use case) into one big test.
  * `// TEST[skip:reason]`: Skip this test. Replace `reason` with the actual
  reason to skip the test. Snippets without `// TEST` or `// CONSOLE` aren't
  considered tests anyway but this is useful for explicitly documenting the
  reason why the test shouldn't be run.
  * `// TEST[setup:name]`: Run some setup code before running the snippet. This
  is useful for creating and populating indexes used in the snippet. The setup
  code is defined in `docs/build.gradle`.
  * `// TEST[warning:some warning]`: Expect the response to include a `Warning`
  header. If the response doesn't include a `Warning` header with the exact
  text then the test fails. If the response includes `Warning` headers that
  aren't expected then the test fails.
* `// TESTRESPONSE`: Matches this snippet against the body of the response of
  the last test. If the response is JSON then order is ignored. With
  `// TEST[continued]` you can make tests that contain multiple command snippets
  and multiple response snippets.
  * `// TESTRESPONSE[s/foo/bar/]`: Substitutions. See `// TEST[s/foo/bar]`.
  * `// TESTRESPONSE[_cat]`: Add substitutions for testing `_cat` responses. Use
  this after all other substitutions so it doesn't make other substitutions
  difficult.
* `// TESTSETUP`: Marks this snippet as the "setup" for all other snippets in
  this file. This is a somewhat natural way of structuring documentation. You
  say "this is the data we use to explain this feature" then you add the
  snippet that you mark `// TESTSETUP` and then every snippet will turn into
  a test that runs the setup snippet first. See the "painless" docs for a file
  that puts this to good use. This is fairly similar to `// TEST[setup:name]`
  but rather than the setup defined in `docs/build.gradle` the setup is defined
  right in the documentation file.

Any place you can use json you can use elements like `$body.path.to.thing`
which is replaced on the fly with the contents of the thing at `path.to.thing`
in the last response.