Adding fromXContent to Suggest and Suggestion class (#23226)

A follow up to #23202, this adds parsing from xContent and tests to the four Suggestion implementations
and the top level suggest element to be used later when parsing the entire SearchResponse.

5 files changed, 76 insertions, 7 deletions

diff --git a/core/src/main/java/org/elasticsearch/common/xcontent/XContentHelper.java b/core/src/main/java/org/elasticsearch/common/xcontent/XContentHelper.java
index 968ad8ac6b..0c6cb1c5cd 100644
--- a/core/src/main/java/org/elasticsearch/common/xcontent/XContentHelper.java
+++ b/core/src/main/java/org/elasticsearch/common/xcontent/XContentHelper.java
@@ -448,12 +448,20 @@ public class XContentHelper {
      * {@link XContentType}. Wraps the output into a new anonymous object.
      */
     public static BytesReference toXContent(ToXContent toXContent, XContentType xContentType, boolean humanReadable) throws IOException {
+        return toXContent(toXContent, xContentType, ToXContent.EMPTY_PARAMS, humanReadable);
+    }
+
+    /**
+     * Returns the bytes that represent the XContent output of the provided {@link ToXContent} object, using the provided
+     * {@link XContentType}. Wraps the output into a new anonymous object.
+     */
+    public static BytesReference toXContent(ToXContent toXContent, XContentType xContentType, Params params, boolean humanReadable) throws IOException {
         try (XContentBuilder builder = XContentBuilder.builder(xContentType.xContent())) {
             builder.humanReadable(humanReadable);
             if (toXContent.isFragment()) {
                 builder.startObject();
             }
-            toXContent.toXContent(builder, ToXContent.EMPTY_PARAMS);
+            toXContent.toXContent(builder, params);
             if (toXContent.isFragment()) {
                 builder.endObject();
             }
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java b/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
index 36a780fec3..ba5ad712f4 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/Suggest.java
@@ -20,6 +20,7 @@ package org.elasticsearch.search.suggest;
 
 import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
@@ -47,17 +48,19 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
+import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpectedToken;
 
 /**
  * Top level suggest result, containing the result for each suggestion.
  */
 public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? extends Option>>>, Streamable, ToXContent {
 
-    private static final String NAME = "suggest";
+    static final String NAME = "suggest";
 
     public static final Comparator<Option> COMPARATOR = (first, second) -> {
         int cmp = Float.compare(second.getScore(), first.getScore());
@@ -72,7 +75,7 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
 
     private Map<String, Suggestion<? extends Entry<? extends Option>>> suggestMap;
 
-    public Suggest() {
+    private Suggest() {
         this(Collections.emptyList());
     }
 
@@ -167,6 +170,18 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
         return builder;
     }
 
+    /**
+     * this parsing method assumes that the leading "suggest" field name has already been parsed by the caller
+     */
+    public static Suggest fromXContent(XContentParser parser) throws IOException {
+        ensureExpectedToken(XContentParser.Token.START_OBJECT, parser.currentToken(), parser::getTokenLocation);
+        List<Suggestion<? extends Entry<? extends Option>>> suggestions = new ArrayList<>();
+        while ((parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+            suggestions.add(Suggestion.fromXContent(parser));
+        }
+        return new Suggest(suggestions);
+    }
+
     public static Suggest readSuggest(StreamInput in) throws IOException {
         Suggest result = new Suggest();
         result.readFrom(in);
@@ -216,7 +231,7 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
         protected int size;
         protected final List<T> entries = new ArrayList<>(5);
 
-        public Suggestion() {
+        protected Suggestion() {
         }
 
         public Suggestion(String name, int size) {
@@ -369,6 +384,52 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
             return builder;
         }
 
+        public static Suggestion<? extends Entry<? extends Option>> fromXContent(XContentParser parser) throws IOException {
+            ensureExpectedToken(XContentParser.Token.FIELD_NAME, parser.currentToken(), parser::getTokenLocation);
+            String typeAndName = parser.currentName();
+            // we need to extract the type prefix from the name and throw error if it is not present
+            int delimiterPos = typeAndName.indexOf(InternalAggregation.TYPED_KEYS_DELIMITER);
+            String type = null;
+            String name = null;
+            if (delimiterPos > 0) {
+                type = typeAndName.substring(0, delimiterPos);
+                name = typeAndName.substring(delimiterPos + 1);
+            } else {
+                throw new ParsingException(parser.getTokenLocation(),
+                        "Cannot parse suggestion response without type information. Set [" + RestSearchAction.TYPED_KEYS_PARAM
+                                + "] parameter on the request to ensure the type information is added to the response output");
+            }
+            Suggestion suggestion = null;
+            Function<XContentParser, Entry> entryParser = null;
+            // the "size" parameter and the SortBy for TermSuggestion cannot be parsed from the response, use default values
+            // TODO investigate if we can use NamedXContentRegistry instead of this switch
+            switch (type) {
+                case Suggestion.NAME:
+                    suggestion = new Suggestion(name, -1);
+                    entryParser = Suggestion.Entry::fromXContent;
+                    break;
+                case PhraseSuggestion.NAME:
+                    suggestion = new PhraseSuggestion(name, -1);
+                    entryParser = PhraseSuggestion.Entry::fromXContent;
+                    break;
+                case TermSuggestion.NAME:
+                    suggestion = new TermSuggestion(name, -1, SortBy.SCORE);
+                    entryParser = TermSuggestion.Entry::fromXContent;
+                    break;
+                case CompletionSuggestion.NAME:
+                    suggestion = new CompletionSuggestion(name, -1);
+                    entryParser = CompletionSuggestion.Entry::fromXContent;
+                    break;
+                default:
+                    throw new ParsingException(parser.getTokenLocation(), "Unknown suggestion type [{}]", type);
+            }
+            ensureExpectedToken(XContentParser.Token.START_ARRAY, parser.nextToken(), parser::getTokenLocation);
+            while ((parser.nextToken()) != XContentParser.Token.END_ARRAY) {
+                suggestion.addTerm(entryParser.apply(parser));
+            }
+            return suggestion;
+        }
+
         /**
          * Represents a part from the suggest text with suggested options.
          */
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
index 51b44a300d..ed45104d99 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java
@@ -64,7 +64,7 @@ import static org.elasticsearch.search.suggest.Suggest.COMPARATOR;
  */
 public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSuggestion.Entry> {
 
-    private static final String NAME = "completion";
+    public static final String NAME = "completion";
 
     public static final int TYPE = 4;
 
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
index 3ea0d61d72..fb646b03ae 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java
@@ -35,7 +35,7 @@ import java.io.IOException;
  */
 public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry> {
 
-    private static final String NAME = "phrase";
+    public static final String NAME = "phrase";
     public static final int TYPE = 3;
 
     public PhraseSuggestion() {
diff --git a/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java b/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
index 5f6cd310ad..31621fb63b 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java
@@ -41,7 +41,7 @@ import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constru
  */
 public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
 
-    private static final String NAME = "term";
+    public static final String NAME = "term";
 
     public static final Comparator<Suggestion.Entry.Option> SCORE = new Score();
     public static final Comparator<Suggestion.Entry.Option> FREQUENCY = new Frequency();