85 lines
2.6 KiB
Plaintext
85 lines
2.6 KiB
Plaintext
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[[modules-scripting-native]]
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=== Native (Java) Scripts
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Sometimes `groovy` and <<modules-scripting-expression, expression>> aren't enough. For those times you can
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implement a native script.
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The best way to implement a native script is to write a plugin and install it.
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The plugin {plugins}/plugin-authors.html[documentation] has more information on
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how to write a plugin so that Elasticsearch will properly load it.
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To register the actual script you'll need to implement `NativeScriptFactory`
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to construct the script. The actual script will extend either
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`AbstractExecutableScript` or `AbstractSearchScript`. The second one is likely
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the most useful and has several helpful subclasses you can extend like
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`AbstractLongSearchScript`, `AbstractDoubleSearchScript`, and
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`AbstractFloatSearchScript`. Finally, your plugin should register the native
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script by declaring the `onModule(ScriptModule)` method.
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If you squashed the whole thing into one class it'd look like:
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[source,java]
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--------------------------------------------------
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public class MyNativeScriptPlugin extends Plugin {
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@Override
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public String name() {
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return "my-native-script";
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}
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@Override
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public String description() {
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return "my native script that does something great";
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}
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public void onModule(ScriptModule scriptModule) {
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scriptModule.registerScript("my_script", MyNativeScriptFactory.class);
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}
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public static class MyNativeScriptFactory implements NativeScriptFactory {
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@Override
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public ExecutableScript newScript(@Nullable Map<String, Object> params) {
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return new MyNativeScript();
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}
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@Override
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public boolean needsScores() {
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return false;
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}
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}
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public static class MyNativeScript extends AbstractFloatSearchScript {
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@Override
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public float runAsFloat() {
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float a = (float) source().get("a");
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float b = (float) source().get("b");
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return a * b;
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}
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}
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}
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--------------------------------------------------
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You can execute the script by specifying its `lang` as `native`, and the name
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of the script as the `id`:
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[source,js]
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--------------------------------------------------
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curl -XPOST localhost:9200/_search -d '{
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"query": {
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"function_score": {
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"query": {
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"match": {
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"body": "foo"
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}
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},
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"functions": [
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{
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"script_score": {
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"script": {
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"id": "my_script",
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"lang" : "native"
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}
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}
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}
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]
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}
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}
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}'
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--------------------------------------------------
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