Enable InstantiatingObjectParser to pass context as a first argument (#79206)

imotov · web-flow · commit 75dbfecfba16 · 2021-10-18T09:07:08.000-10:00
This is a followup for #78790, which allows us to replace ConstructingObjectParser with InstantiatingObjectParser which makes keeping track of the positional arguments somewhat easier.
diff --git a/libs/x-content/src/main/java/org/elasticsearch/xcontent/InstantiatingObjectParser.java b/libs/x-content/src/main/java/org/elasticsearch/xcontent/InstantiatingObjectParser.java
@@ -23,8 +23,12 @@
  * <p>
  * The main differences being that it is using Builder to construct the parser and takes a class of the target object instead of the object
  * builder. The target object must have exactly one constructor with the number and order of arguments matching the number of order of
- * declared fields. If there are more then 2 constructors with the same number of arguments, one of them needs to be marked with
+ * declared fields. If there are more than 2 constructors with the same number of arguments, one of them needs to be marked with
  * {@linkplain ParserConstructor} annotation.
+ *
+ * It is also possible for the constructor to accept Context as the first parameter, in this case as in the case with multiple constructors
+ * it is required for the constructor to be marked with {@linkplain ParserConstructor} annotation.
+ *
  * <pre>{@code
  *   public static class Thing{
  *       public Thing(String animal, String vegetable, int mineral) {
@@ -37,14 +41,35 @@
  *
  *   }
  *
- *   private static final InstantiatingObjectParser<Thing, SomeContext> PARSER = new InstantiatingObjectParser<>("thing", Thing.class);
+ *   private static final InstantiatingObjectParser<Thing, SomeContext> PARSER;
+ *   static {
+ *       InstantiatingObjectParser.Builder<Thing, SomeContext> parser =
+ *           InstantiatingObjectParser,builder<>("thing", true, Thing.class);
+ *       parser.declareString(constructorArg(), new ParseField("animal"));
+ *       parser.declareString(constructorArg(), new ParseField("vegetable"));
+ *       parser.declareInt(optionalConstructorArg(), new ParseField("mineral"));
+ *       parser.declareInt(Thing::setFruit, new ParseField("fruit"));
+ *       parser.declareInt(Thing::setBug, new ParseField("bug"));
+ *       PARSER = parser.build()
+ *   }
+ * }</pre>
+ * <pre>{@code
+ *
+ *   public static class AnotherThing {
+ *       @ParserConstructor
+ *       public AnotherThing(SomeContext continent, String animal, String vegetable, int mineral) {
+ *           ....
+ *       }
+ *   }
+ *
+ *   private static final InstantiatingObjectParser<AnotherThing, SomeContext> PARSER;
  *   static {
- *       PARSER.declareString(constructorArg(), new ParseField("animal"));
- *       PARSER.declareString(constructorArg(), new ParseField("vegetable"));
- *       PARSER.declareInt(optionalConstructorArg(), new ParseField("mineral"));
- *       PARSER.declareInt(Thing::setFruit, new ParseField("fruit"));
- *       PARSER.declareInt(Thing::setBug, new ParseField("bug"));
- *       PARSER.finalizeFields()
+ *       InstantiatingObjectParser.Builder<AnotherThing, SomeContext> parser =
+ *           InstantiatingObjectParser,builder<>("thing", true, AnotherThing.class);
+ *       parser.declareString(constructorArg(), new ParseField("animal"));
+ *       parser.declareString(constructorArg(), new ParseField("vegetable"));
+ *       parser.declareInt(optionalConstructorArg(), new ParseField("mineral"));
+ *       PARSER = parser.build()
  *   }
  * }</pre>
  */
@@ -72,7 +97,7 @@ public Builder(String name, Class<Value> valueClass) {
         }
 
         public Builder(String name, boolean ignoreUnknownFields, Class<Value> valueClass) {
-            this.constructingObjectParser = new ConstructingObjectParser<>(name, ignoreUnknownFields, this::build);
+            this.constructingObjectParser = new ConstructingObjectParser<>(name, ignoreUnknownFields, this::buildInstance);
             this.valueClass = valueClass;
         }
 
@@ -87,9 +112,15 @@ public InstantiatingObjectParser<Value, Context> build() {
                         throw new IllegalArgumentException("More then one public constructor with @ParserConstructor annotation exist in " +
                             "the class " + valueClass.getName());
                     }
-                    if (c.getParameterCount() != neededArguments) {
-                        throw new IllegalArgumentException("Annotated constructor doesn't have " + neededArguments +
-                            " arguments in the class " + valueClass.getName());
+                    if (c.getParameterCount() < neededArguments || c.getParameterCount() > neededArguments + 1) {
+                        throw new IllegalArgumentException(
+                            "Annotated constructor doesn't have "
+                                + neededArguments
+                                + " or "
+                                + (neededArguments + 1)
+                                + " arguments in the class "
+                                + valueClass.getName()
+                        );
                     }
                     constructor = c;
                 }
@@ -154,13 +185,20 @@ public void declareExclusiveFieldSet(String... exclusiveSet) {
             constructingObjectParser.declareExclusiveFieldSet(exclusiveSet);
         }
 
-        private Value build(Object[] args) {
+        private Value buildInstance(Object[] args, Context context) {
             if (constructor == null) {
                 throw new IllegalArgumentException("InstantiatingObjectParser for type " + valueClass.getName() + " has to be finalized " +
                     "before the first use");
             }
             try {
-                return constructor.newInstance(args);
+                if (constructor.getParameterCount() != args.length) {
+                    Object[] newArgs = new Object[args.length + 1];
+                    System.arraycopy(args, 0, newArgs, 1, args.length);
+                    newArgs[0] = context;
+                    return constructor.newInstance(newArgs);
+                } else {
+                    return constructor.newInstance(args);
+                }
             } catch (Exception ex) {
                 throw new IllegalArgumentException("Cannot instantiate an object of " + valueClass.getName(), ex);
             }
diff --git a/libs/x-content/src/test/java/org/elasticsearch/xcontent/InstantiatingObjectParserTests.java b/libs/x-content/src/test/java/org/elasticsearch/xcontent/InstantiatingObjectParserTests.java
@@ -8,11 +8,8 @@
 
 package org.elasticsearch.xcontent;
 
-import org.elasticsearch.xcontent.InstantiatingObjectParser;
-import org.elasticsearch.xcontent.ParseField;
-import org.elasticsearch.xcontent.ParserConstructor;
-import org.elasticsearch.xcontent.json.JsonXContent;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.json.JsonXContent;
 
 import java.io.IOException;
 import java.util.Objects;
@@ -217,8 +214,10 @@ public void testAnnotationWrongArgumentNumber() {
         InstantiatingObjectParser.Builder<Annotations, Void> builder = InstantiatingObjectParser.builder("foo", Annotations.class);
         builder.declareInt(constructorArg(), new ParseField("a"));
         builder.declareString(constructorArg(), new ParseField("b"));
+        builder.declareInt(constructorArg(), new ParseField("c"));
+        builder.declareString(constructorArg(), new ParseField("d"));
         IllegalArgumentException e = expectThrows(IllegalArgumentException.class, builder::build);
-        assertThat(e.getMessage(), containsString("Annotated constructor doesn't have 2 arguments in the class"));
+        assertThat(e.getMessage(), containsString("Annotated constructor doesn't have 4 or 5 arguments in the class"));
     }
 
     public void testDoubleDeclarationThrowsException() throws IOException {
@@ -240,4 +239,80 @@ class DoubleFieldDeclaration {
         assertThat(exception, instanceOf(IllegalArgumentException.class));
         assertThat(exception.getMessage(), startsWith("Parser already registered for name=[name]"));
     }
+
+    public static class ContextArgument {
+        final String context;
+        final int a;
+        final String b;
+        final long c;
+
+        public ContextArgument() {
+            this(1, "2", 3);
+        }
+
+        public ContextArgument(int a, String b) {
+            this(a, b, -1);
+        }
+
+
+        public ContextArgument(int a, String b, long c) {
+            this(null, a, b, c);
+        }
+
+        public ContextArgument(String context, int a, String b, long c) {
+            this.context = context;
+            this.a = a;
+            this.b = b;
+            this.c = c;
+        }
+
+        @ParserConstructor
+        public ContextArgument(String context, int a, String b, String c) {
+            this.context = context;
+            this.a = a;
+            this.b = b;
+            this.c = Long.parseLong(c);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            ContextArgument that = (ContextArgument) o;
+            return a == that.a &&
+                c == that.c &&
+                Objects.equals(b, that.b);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(a, b, c);
+        }
+    }
+
+    public void testContextAsArgument() throws IOException {
+        InstantiatingObjectParser.Builder<ContextArgument, String> builder = InstantiatingObjectParser.builder(
+            "foo",
+            ContextArgument.class
+        );
+        builder.declareInt(constructorArg(), new ParseField("a"));
+        builder.declareString(constructorArg(), new ParseField("b"));
+        builder.declareString(constructorArg(), new ParseField("c"));
+        InstantiatingObjectParser<ContextArgument, String> parser = builder.build();
+        try (XContentParser contentParser = createParser(JsonXContent.jsonXContent, "{\"a\": 5, \"b\":\"6\", \"c\": \"7\"}")) {
+            assertThat(parser.parse(contentParser, "context"), equalTo(new ContextArgument("context", 5, "6", 7)));
+        }
+    }
+
+    public void testContextAsArgumentWrongArgumentNumber() {
+        InstantiatingObjectParser.Builder<ContextArgument, String> builder = InstantiatingObjectParser.builder(
+            "foo",
+            ContextArgument.class
+        );
+        builder.declareInt(constructorArg(), new ParseField("a"));
+        builder.declareString(constructorArg(), new ParseField("b"));
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, builder::build);
+        assertThat(e.getMessage(), containsString("Annotated constructor doesn't have 2 or 3 arguments in the class"));
+    }
+
 }
diff --git a/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilities.java b/server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilities.java
@@ -10,12 +10,14 @@
 
 import org.elasticsearch.Version;
 import org.elasticsearch.index.mapper.TimeSeriesParams;
+import org.elasticsearch.xcontent.InstantiatingObjectParser;
 import org.elasticsearch.xcontent.ParseField;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.xcontent.ConstructingObjectParser;
+import org.elasticsearch.xcontent.ParserConstructor;
 import org.elasticsearch.xcontent.ToXContentObject;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xcontent.XContentParser;
@@ -159,6 +161,59 @@ public FieldCapabilities(String name, String type,
 
     }
 
+    /**
+     * Constructor for a set of indices used by parser
+     * @param name The name of the field
+     * @param type The type associated with the field.
+     * @param isMetadataField Whether this field is a metadata field.
+     * @param isSearchable Whether this field is indexed for search.
+     * @param isAggregatable Whether this field can be aggregated on.
+     * @param isDimension Whether this field can be used as dimension
+     * @param metricType If this field is a metric field, returns the metric's type or null for non-metrics fields
+     * @param indices The list of indices where this field name is defined as {@code type},
+     *                or null if all indices have the same {@code type} for the field.
+     * @param nonSearchableIndices The list of indices where this field is not searchable,
+     *                             or null if the field is searchable in all indices.
+     * @param nonAggregatableIndices The list of indices where this field is not aggregatable,
+     *                               or null if the field is aggregatable in all indices.
+     * @param nonDimensionIndices The list of indices where this field is not a dimension
+     * @param metricConflictsIndices The list of indices where this field is has different metric types or not mark as a metric
+     * @param meta Merged metadata across indices.
+     */
+    @SuppressWarnings("unused")
+    @ParserConstructor
+    public FieldCapabilities(
+        String name,
+        String type,
+        Boolean isMetadataField,
+        boolean isSearchable,
+        boolean isAggregatable,
+        Boolean isDimension,
+        String metricType,
+        List<String> indices,
+        List<String> nonSearchableIndices,
+        List<String> nonAggregatableIndices,
+        List<String> nonDimensionIndices,
+        List<String> metricConflictsIndices,
+        Map<String, Set<String>> meta
+    ) {
+        this(
+            name,
+            type,
+            isMetadataField == null ? false : isMetadataField,
+            isSearchable,
+            isAggregatable,
+            isDimension == null ? false : isDimension,
+            metricType != null ? Enum.valueOf(TimeSeriesParams.MetricType.class, metricType) : null,
+            indices != null ? indices.toArray(new String[0]) : null,
+            nonSearchableIndices != null ? nonSearchableIndices.toArray(new String[0]) : null,
+            nonAggregatableIndices != null ? nonAggregatableIndices.toArray(new String[0]) : null,
+            nonDimensionIndices != null ? nonDimensionIndices.toArray(new String[0]) : null,
+            metricConflictsIndices != null ? metricConflictsIndices.toArray(new String[0]) : null,
+            meta != null ? meta : Collections.emptyMap()
+        );
+    }
+
     FieldCapabilities(StreamInput in) throws IOException {
         this.name = in.readString();
         this.type = in.readString();
@@ -254,43 +309,31 @@ public static FieldCapabilities fromXContent(String name, XContentParser parser)
     }
 
     @SuppressWarnings("unchecked")
-    private static final ConstructingObjectParser<FieldCapabilities, String> PARSER = new ConstructingObjectParser<>(
-        "field_capabilities",
-        true,
-        (a, name) -> new FieldCapabilities(
-            name,
-            (String) a[0],
-            a[3] == null ? false : (boolean) a[3],
-            (boolean) a[1],
-            (boolean) a[2],
-            a[4] == null ? false : (boolean) a[4],
-            a[5] != null ? Enum.valueOf(TimeSeriesParams.MetricType.class, (String) a[5]) : null,
-            a[6] != null ? ((List<String>) a[6]).toArray(new String[0]) : null,
-            a[7] != null ? ((List<String>) a[7]).toArray(new String[0]) : null,
-            a[8] != null ? ((List<String>) a[8]).toArray(new String[0]) : null,
-            a[9] != null ? ((List<String>) a[9]).toArray(new String[0]) : null,
-            a[10] != null ? ((List<String>) a[10]).toArray(new String[0]) : null,
-            a[11] != null ? ((Map<String, Set<String>>) a[11]) : Collections.emptyMap()
-        )
-    );
+    private static final InstantiatingObjectParser<FieldCapabilities, String> PARSER;
 
     static {
-        PARSER.declareString(ConstructingObjectParser.constructorArg(), TYPE_FIELD); // 0
-        PARSER.declareBoolean(ConstructingObjectParser.constructorArg(), SEARCHABLE_FIELD); // 1
-        PARSER.declareBoolean(ConstructingObjectParser.constructorArg(), AGGREGATABLE_FIELD); // 2
-        PARSER.declareBoolean(ConstructingObjectParser.optionalConstructorArg(), IS_METADATA_FIELD); // 3
-        PARSER.declareBoolean(ConstructingObjectParser.optionalConstructorArg(), TIME_SERIES_DIMENSION_FIELD); // 4
-        PARSER.declareString(ConstructingObjectParser.optionalConstructorArg(), TIME_SERIES_METRIC_FIELD); // 5
-        PARSER.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), INDICES_FIELD); // 6
-        PARSER.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_SEARCHABLE_INDICES_FIELD); // 7
-        PARSER.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_AGGREGATABLE_INDICES_FIELD); // 8
-        PARSER.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_DIMENSION_INDICES_FIELD); // 9
-        PARSER.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), METRIC_CONFLICTS_INDICES_FIELD); // 10
-        PARSER.declareObject(
+        InstantiatingObjectParser.Builder<FieldCapabilities, String> parser = InstantiatingObjectParser.builder(
+            "field_capabilities",
+            true,
+            FieldCapabilities.class
+        );
+        parser.declareString(ConstructingObjectParser.constructorArg(), TYPE_FIELD);
+        parser.declareBoolean(ConstructingObjectParser.optionalConstructorArg(), IS_METADATA_FIELD);
+        parser.declareBoolean(ConstructingObjectParser.constructorArg(), SEARCHABLE_FIELD);
+        parser.declareBoolean(ConstructingObjectParser.constructorArg(), AGGREGATABLE_FIELD);
+        parser.declareBoolean(ConstructingObjectParser.optionalConstructorArg(), TIME_SERIES_DIMENSION_FIELD);
+        parser.declareString(ConstructingObjectParser.optionalConstructorArg(), TIME_SERIES_METRIC_FIELD);
+        parser.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), INDICES_FIELD);
+        parser.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_SEARCHABLE_INDICES_FIELD);
+        parser.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_AGGREGATABLE_INDICES_FIELD);
+        parser.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), NON_DIMENSION_INDICES_FIELD);
+        parser.declareStringArray(ConstructingObjectParser.optionalConstructorArg(), METRIC_CONFLICTS_INDICES_FIELD);
+        parser.declareObject(
             ConstructingObjectParser.optionalConstructorArg(),
-            (parser, context) -> parser.map(HashMap::new, p -> Set.copyOf(p.list())),
+            (p, context) -> p.map(HashMap::new, v -> Set.copyOf(v.list())),
             META_FIELD
-        ); // 11
+        );
+        PARSER = parser.build();
     }
 
     /**
