New field mapping flag - allow_multiple_values

docs/reference/mapping/types.asciidoc

@@ -112,7 +112,7 @@ as-you-type completion.
 === Arrays
 In {es}, arrays do not require a dedicated field data type. Any field can contain
 zero or more values by default, however, all values in the array must be of the
-same field type. See <<array>>.
+same field type. See <<array>> for more detail (including how to reject array values).
 
 [discrete]
 [[types-multi-fields]]

docs/reference/mapping/types/array.asciidoc

@@ -81,3 +81,14 @@ GET my-index-000001/_search
 <3> The second document contains no arrays, but can be indexed into the same fields.
 <4> The query looks for `elasticsearch` in the `tags` field, and matches both documents.
 
+.Rejecting documents with arrays
+[NOTE]
+====================================================
+
+It is possible to reject documents with array values for a field
+by using the `allow_multiple_values` setting in the field's index mapping.
+The default value for fields is `true`, meaning arrays are accepted.
+When this property is set to `false` documents that present arrays instead of single
+values are rejected with an error.
+
+====================================================

docs/reference/mapping/types/boolean.asciidoc

@@ -166,6 +166,12 @@ The following parameters are accepted by `boolean` fields:
 
 [horizontal]
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<doc-values,`doc_values`>>::
 
     Should the field be stored on disk in a column-stride fashion, so that it

docs/reference/mapping/types/date.asciidoc

@@ -112,6 +112,12 @@ The following parameters are accepted by `date` fields:
 
 [horizontal]
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<doc-values,`doc_values`>>::
 
     Should the field be stored on disk in a column-stride fashion, so that it

docs/reference/mapping/types/ip.asciidoc

@@ -43,6 +43,12 @@ NOTE: You can also store ip ranges in a single field using an <<range,ip_range d
 
 The following parameters are accepted by `ip` fields:
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<doc-values,`doc_values`>>::
 
     Should the field be stored on disk in a column-stride fashion, so that it

docs/reference/mapping/types/keyword.asciidoc

@@ -53,6 +53,12 @@ include::numeric.asciidoc[tag=map-ids-as-keyword]
 
 The following parameters are accepted by `keyword` fields:
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<doc-values,`doc_values`>>::
 
     Should the field be stored on disk in a column-stride fashion, so that it

docs/reference/mapping/types/numeric.asciidoc

@@ -111,6 +111,12 @@ the data as both a `keyword` _and_ a numeric data type.
 
 The following parameters are accepted by numeric types:
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<coerce,`coerce`>>::
 
     Try to convert strings to numbers and truncate fractions for integers.

docs/reference/mapping/types/object.asciidoc

@@ -79,6 +79,12 @@ You are not required to set the field `type` to `object` explicitly, as this is
 The following parameters are accepted by `object` fields:
 
 [horizontal]
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<dynamic,`dynamic`>>::
 
     Whether or not new `properties` should be added dynamically

docs/reference/mapping/types/range.asciidoc

@@ -214,6 +214,11 @@ PUT range_index/_doc/2
 The following parameters are accepted by range types:
 
 [horizontal]
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
 
 <<coerce,`coerce`>>::
 

docs/reference/mapping/types/version.asciidoc

@@ -9,7 +9,7 @@ The `version` field type is a specialization of the `keyword` field for
 handling software version values and to support specialized precedence
 rules for them. Precedence is defined following the rules outlined by
 https://semver.org/[Semantic Versioning], which for example means that
-major, minor and patch version parts are sorted numerically (i.e. 
+major, minor and patch version parts are sorted numerically (i.e.
 "2.1.0" < "2.4.1" < "2.11.2") and pre-release versions are sorted before
 release versions (i.e. "1.0.0-alpha" < "1.0.0").
 
@@ -30,7 +30,7 @@ PUT my-index-000001
 
 --------------------------------------------------
 
-The field offers the same search capabilities as a regular keyword field. It 
+The field offers the same search capabilities as a regular keyword field. It
 can e.g. be searched for exact matches using `match` or `term` queries and
 supports prefix and wildcard searches. The main benefit is that `range` queries
 will honor Semver ordering, so a `range` query between "1.0.0" and "1.5.0"
@@ -56,6 +56,12 @@ The following parameters are accepted by `version` fields:
 
 [horizontal]
 
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
+
 <<mapping-field-meta,`meta`>>::
 
     Metadata about the field.

docs/reference/mapping/types/wildcard.asciidoc

@@ -114,6 +114,11 @@ GET my-index-000001/_search
 The following parameters are accepted by `wildcard` fields:
 
 [horizontal]
+`allow_multiple_values`::
+
+    Should the field permit arrays of values?  Accepts `true`
+    (default) or `false`. When `false`, documents presenting arrays
+    of values for this field will be rejected with an error.
 
 <<null-value,`null_value`>>::
 

modules/legacy-geo/src/main/java/org/elasticsearch/legacygeo/mapper/LegacyGeoShapeFieldMapper.java

@@ -563,6 +563,7 @@ public LegacyGeoShapeFieldMapper(
             builder.orientation.get(),
             multiFields,
             copyTo,
+            builder.getAllowMultipleValues(),
             parser
         );
         this.indexCreatedVersion = builder.indexCreatedVersion;

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/RankFeatureFieldMapper.java

@@ -74,6 +74,12 @@ protected List<Parameter<?>> getParameters() {
             return Arrays.asList(positiveScoreImpact, meta);
         }
 
+        @Override
+        protected boolean supportsAllowMultipleValuesChoice() {
+            // We don't allow users to redefine if multiple values are allowed - they are never allowed.
+            return false;
+        }
+
         @Override
         public RankFeatureFieldMapper build(MapperBuilderContext context) {
             return new RankFeatureFieldMapper(

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/RankFeaturesFieldMapper.java

@@ -59,6 +59,12 @@ protected List<Parameter<?>> getParameters() {
             return List.of(positiveScoreImpact, meta);
         }
 
+        @Override
+        protected boolean supportsAllowMultipleValuesChoice() {
+            // We don't allow users to redefine if multiple values are allowed - they are never allowed.
+            return false;
+        }
+
         @Override
         public RankFeaturesFieldMapper build(MapperBuilderContext context) {
             return new RankFeaturesFieldMapper(

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/SearchAsYouTypeFieldMapper.java

@@ -141,6 +141,12 @@ public static class Builder extends FieldMapper.Builder {
 
         private final Parameter<Map<String, String>> meta = Parameter.metaParam();
 
+        @Override
+        protected boolean supportsAllowMultipleValuesChoice() {
+            // We don't allow users to redefine if multiple values are allowed - they are always allowed.
+            return false;
+        }
+
         public Builder(String name, IndexAnalyzers indexAnalyzers) {
             super(name);
             this.analyzers = new TextParams.Analyzers(
@@ -646,7 +652,7 @@ public SearchAsYouTypeFieldMapper(
         ShingleFieldMapper[] shingleFields,
         Builder builder
     ) {
-        super(simpleName, mappedFieldType, indexAnalyzers, MultiFields.empty(), copyTo, false, null);
+        super(simpleName, mappedFieldType, indexAnalyzers, MultiFields.empty(), copyTo, true, false, null);
         this.prefixField = prefixField;
         this.shingleFields = shingleFields;
         this.maxShingleSize = builder.maxShingleSize.getValue();

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/TokenCountFieldMapper.java

@@ -72,6 +72,12 @@ protected List<Parameter<?>> getParameters() {
             return Arrays.asList(index, hasDocValues, store, analyzer, nullValue, enablePositionIncrements, meta);
         }
 
+        @Override
+        protected boolean supportsAllowMultipleValuesChoice() {
+            // Disable the default of parsing `allow_multiple_values` setting.
+            return false;
+        }
+
         @Override
         public TokenCountFieldMapper build(MapperBuilderContext context) {
             if (analyzer.getValue() == null) {

modules/parent-join/src/main/java/org/elasticsearch/join/mapper/ParentJoinFieldMapper.java

@@ -119,6 +119,12 @@ protected List<Parameter<?>> getParameters() {
             return Arrays.asList(eagerGlobalOrdinals, relations, meta);
         }
 
+        @Override
+        protected boolean supportsAllowMultipleValuesChoice() {
+            // Disable the default of parsing `allow_multiple_values` setting.
+            return false;
+        }
+
         @Override
         public ParentJoinFieldMapper build(MapperBuilderContext context) {
             checkObjectOrNested(context, name);
@@ -208,6 +214,7 @@ protected ParentJoinFieldMapper(
         boolean eagerGlobalOrdinals,
         List<Relations> relations
     ) {
+        // TODO pass allowMultipleValues = false here? DocumentParser would then reject any arrays
         super(simpleName, mappedFieldType, Lucene.KEYWORD_ANALYZER, MultiFields.empty(), CopyTo.empty());
         this.parentIdFields = parentIdFields;
         this.eagerGlobalOrdinals = eagerGlobalOrdinals;

plugins/mapper-annotated-text/src/main/java/org/elasticsearch/index/mapper/annotatedtext/AnnotatedTextFieldMapper.java

@@ -531,7 +531,14 @@ protected AnnotatedTextFieldMapper(
         CopyTo copyTo,
         Builder builder
     ) {
-        super(simpleName, mappedFieldType, wrapAnalyzer(builder.analyzers.getIndexAnalyzer()), multiFields, copyTo);
+        super(
+            simpleName,
+            mappedFieldType,
+            wrapAnalyzer(builder.analyzers.getIndexAnalyzer()),
+            multiFields,
+            copyTo,
+            builder.getAllowMultipleValues()
+        );
         assert fieldType.tokenized();
         this.fieldType = fieldType;
         this.builder = builder;

server/src/main/java/org/elasticsearch/index/mapper/AbstractGeometryFieldMapper.java

@@ -123,9 +123,10 @@ protected AbstractGeometryFieldMapper(
         Explicit<Boolean> ignoreZValue,
         MultiFields multiFields,
         CopyTo copyTo,
+        boolean allowMultipleValues,
         Parser<T> parser
     ) {
-        super(simpleName, mappedFieldType, indexAnalyzers, multiFields, copyTo, false, null);
+        super(simpleName, mappedFieldType, indexAnalyzers, multiFields, copyTo, allowMultipleValues, false, null);
         this.ignoreMalformed = ignoreMalformed;
         this.ignoreZValue = ignoreZValue;
         this.parser = parser;
@@ -138,20 +139,32 @@ protected AbstractGeometryFieldMapper(
         Explicit<Boolean> ignoreZValue,
         MultiFields multiFields,
         CopyTo copyTo,
+        boolean allowMultipleValues,
         Parser<T> parser
     ) {
-        this(simpleName, mappedFieldType, Collections.emptyMap(), ignoreMalformed, ignoreZValue, multiFields, copyTo, parser);
+        this(
+            simpleName,
+            mappedFieldType,
+            Collections.emptyMap(),
+            ignoreMalformed,
+            ignoreZValue,
+            multiFields,
+            copyTo,
+            allowMultipleValues,
+            parser
+        );
     }
 
     protected AbstractGeometryFieldMapper(
         String simpleName,
         MappedFieldType mappedFieldType,
         MultiFields multiFields,
         CopyTo copyTo,
+        boolean allowMultipleValues,
         Parser<T> parser,
         String onScriptError
     ) {
-        super(simpleName, mappedFieldType, Collections.emptyMap(), multiFields, copyTo, true, onScriptError);
+        super(simpleName, mappedFieldType, Collections.emptyMap(), multiFields, copyTo, allowMultipleValues, true, onScriptError);
         this.ignoreMalformed = new Explicit<>(false, true);
         this.ignoreZValue = new Explicit<>(false, true);
         this.parser = parser;

server/src/main/java/org/elasticsearch/index/mapper/AbstractPointGeometryFieldMapper.java

@@ -42,7 +42,7 @@ protected AbstractPointGeometryFieldMapper(
         CopyTo copyTo,
         Parser<T> parser
     ) {
-        super(simpleName, mappedFieldType, ignoreMalformed, ignoreZValue, multiFields, copyTo, parser);
+        super(simpleName, mappedFieldType, ignoreMalformed, ignoreZValue, multiFields, copyTo, true, parser);
         this.nullValue = nullValue;
     }
 
@@ -54,7 +54,7 @@ protected AbstractPointGeometryFieldMapper(
         Parser<T> parser,
         String onScriptError
     ) {
-        super(simpleName, mappedFieldType, multiFields, copyTo, parser, onScriptError);
+        super(simpleName, mappedFieldType, multiFields, copyTo, true, parser, onScriptError);
         this.nullValue = null;
     }
 

server/src/main/java/org/elasticsearch/index/mapper/AbstractShapeGeometryFieldMapper.java

@@ -69,9 +69,10 @@ protected AbstractShapeGeometryFieldMapper(
         Explicit<Orientation> orientation,
         MultiFields multiFields,
         CopyTo copyTo,
+        boolean allowMultipleValues,
         Parser<T> parser
     ) {
-        super(simpleName, mappedFieldType, indexAnalyzers, ignoreMalformed, ignoreZValue, multiFields, copyTo, parser);
+        super(simpleName, mappedFieldType, indexAnalyzers, ignoreMalformed, ignoreZValue, multiFields, copyTo, allowMultipleValues, parser);
         this.coerce = coerce;
         this.orientation = orientation;
     }
@@ -85,6 +86,7 @@ protected AbstractShapeGeometryFieldMapper(
         Explicit<Orientation> orientation,
         MultiFields multiFields,
         CopyTo copyTo,
+        boolean allowMultipleValues,
         Parser<T> parser
     ) {
         this(
@@ -97,6 +99,7 @@ protected AbstractShapeGeometryFieldMapper(
             orientation,
             multiFields,
             copyTo,
+            allowMultipleValues,
             parser
         );
     }

server/src/main/java/org/elasticsearch/index/mapper/BinaryFieldMapper.java

@@ -142,7 +142,7 @@ protected BinaryFieldMapper(
         CopyTo copyTo,
         Builder builder
     ) {
-        super(simpleName, mappedFieldType, multiFields, copyTo);
+        super(simpleName, mappedFieldType, multiFields, copyTo, builder.allowMultipleValues);
         this.stored = builder.stored.getValue();
         this.hasDocValues = builder.hasDocValues.getValue();
     }

server/src/main/java/org/elasticsearch/index/mapper/BooleanFieldMapper.java

@@ -277,6 +277,7 @@ protected BooleanFieldMapper(
             Lucene.KEYWORD_ANALYZER,
             multiFields,
             copyTo,
+            builder.allowMultipleValues,
             builder.script.get() != null,
             builder.onScriptError.getValue()
         );

server/src/main/java/org/elasticsearch/index/mapper/DateFieldMapper.java

@@ -720,7 +720,15 @@ private DateFieldMapper(
         Resolution resolution,
         Builder builder
     ) {
-        super(simpleName, mappedFieldType, multiFields, copyTo, builder.script.get() != null, builder.onScriptError.get());
+        super(
+            simpleName,
+            mappedFieldType,
+            multiFields,
+            copyTo,
+            builder.allowMultipleValues,
+            builder.script.get() != null,
+            builder.onScriptError.get()
+        );
         this.store = builder.store.getValue();
         this.indexed = builder.index.getValue();
         this.hasDocValues = builder.docValues.getValue();