Runtime fields to expose _source and stored fields like other script fields

This commit exposes stored fields to runtime fields (through params._fields) and replaces the current way to access _source (source['field']) in favour of the documented way for all existing scripts: params._source .

Author: javanna

x-pack/plugin/runtime-fields/qa/rest/src/yamlRestTest/java/org/elasticsearch/xpack/runtimefields/rest/CoreTestsWithRuntimeFieldsIT.java

@@ -166,7 +166,7 @@ private static String painlessToLoadFromSource(String name, String type) {
             return null;
         }
         StringBuilder b = new StringBuilder();
-        b.append("def v = source['").append(name).append("'];\n");
+        b.append("def v = params._source.").append(name).append(";\n");
         b.append("if (v instanceof Iterable) {\n");
         b.append("  for (def vv : ((Iterable) v)) {\n");
         b.append("    if (vv != null) {\n");

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/AbstractScriptFieldScript.java

@@ -9,12 +9,16 @@
 import org.apache.lucene.index.LeafReaderContext;
 import org.elasticsearch.index.fielddata.ScriptDocValues;
 import org.elasticsearch.script.AggregationScript;
+import org.elasticsearch.script.DynamicMap;
 import org.elasticsearch.script.ScriptCache;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.search.lookup.LeafSearchLookup;
 import org.elasticsearch.search.lookup.SearchLookup;
+import org.elasticsearch.search.lookup.SourceLookup;
 
+import java.util.HashMap;
 import java.util.Map;
+import java.util.function.Function;
 
 import static org.elasticsearch.common.unit.TimeValue.timeValueMillis;
 
@@ -45,13 +49,25 @@ public static <F> ScriptContext<F> newContext(String name, Class<F> factoryClass
         );
     }
 
+    private static final Map<String, Function<Object, Object>> PARAMS_FUNCTIONS = Map.of(
+        "_source",
+        value -> ((SourceLookup) value).loadSourceIfNeeded()
+    );
+
     private final Map<String, Object> params;
     private final LeafSearchLookup leafSearchLookup;
 
     public AbstractScriptFieldScript(Map<String, Object> params, SearchLookup searchLookup, LeafReaderContext ctx) {
         this.leafSearchLookup = searchLookup.getLeafSearchLookup(ctx);
-        // TODO how do other scripts get stored fields exposed? Through asMap? I don't see any getters for them.
-        this.params = params;
+        params = new HashMap<>(params);
+        for (Map.Entry<String, Object> entry : leafSearchLookup.asMap().entrySet()) {
+            // accessing doc_values through through params._doc and params.doc is deprecated in all existing script contexts,
+            // it makes little sense to expose it deprecated for runtime fields
+            if (entry.getKey().equals("_doc") == false && entry.getKey().equals("doc") == false) {
+                params.put(entry.getKey(), entry.getValue());
+            }
+        }
+        this.params = new DynamicMap(params, PARAMS_FUNCTIONS);
     }
 
     /**
@@ -71,7 +87,7 @@ public final Map<String, Object> getParams() {
     /**
      * Expose the {@code _source} to the script.
      */
-    public final Map<String, Object> getSource() {
+    protected final Map<String, Object> getSource() {
         return leafSearchLookup.source();
     }
 

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/10_keyword.yml

@@ -17,6 +17,7 @@ setup:
                 type: double
               node:
                 type: keyword
+                store: true
               day_of_week:
                 type: runtime_script
                 runtime_type: keyword
@@ -27,7 +28,7 @@ setup:
                 type: runtime_script
                 runtime_type: keyword
                 script: |
-                  Instant instant = Instant.ofEpochMilli(source['timestamp']);
+                  Instant instant = Instant.ofEpochMilli(params._source.timestamp);
                   ZonedDateTime dt = ZonedDateTime.ofInstant(instant, ZoneId.of("UTC"));
                   emitValue(dt.dayOfWeek.getDisplayName(TextStyle.FULL, Locale.ROOT));
               # Test fetching many values
@@ -45,7 +46,7 @@ setup:
                 runtime_type: keyword
                 script:
                   source: |
-                    for (String node : doc['node']) {
+                    for (String node : params._fields.node.values) {
                       emitValue(params.prefix + node);
                     }
                   params:

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/20_long.yml

@@ -33,7 +33,7 @@ setup:
                 runtime_type: long
                 script:
                   source: |
-                    emitValue((long)(source['voltage'] * params.multiplier));
+                    emitValue((long)(params._source.voltage * params.multiplier));
                   params:
                     multiplier: 10
               # Test fetching many values

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/30_double.yml

@@ -33,7 +33,7 @@ setup:
                 runtime_type: double
                 script:
                   source: |
-                    emitValue(source['voltage'] / params.max);
+                    emitValue(params._source.voltage / params.max);
                   params:
                     max: 5.8
               # Test fetching many values

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/40_date.yml

@@ -33,7 +33,7 @@ setup:
                 runtime_type: date
                 script:
                   source: |
-                    Instant instant = Instant.ofEpochMilli(parse(source['timestamp']));
+                    Instant instant = Instant.ofEpochMilli(parse(params._source.timestamp));
                     ZonedDateTime dt = ZonedDateTime.ofInstant(instant, ZoneId.of("UTC"));
                     emitValue(toEpochMilli(dt.plus(1, ChronoUnit.DAYS)));
               # Test returning millis

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/50_ip.yml

@@ -27,7 +27,7 @@ setup:
                 runtime_type: ip
                 script:
                   source: |
-                    String m = source["message"];
+                    String m = params._source.message;
                     int end = m.indexOf(" ");
                     emitValue(m.substring(0, end));
               # Test emitting many values

x-pack/plugin/src/test/resources/rest-api-spec/test/runtime_fields/60_boolean.yml

@@ -33,7 +33,7 @@ setup:
                 runtime_type: boolean
                 script:
                   source: |
-                    emitValue(source['voltage'] >= 5.0);
+                    emitValue(params._source.voltage >= 5.0);
               # Test many booleans
               big_vals:
                 type: runtime_script