SQL feature provider: add nullOrder option

xtraplatform-features-sql/src/main/java/de/ii/xtraplatform/features/sql/app/SqlQueryTemplatesDeriver.java

@@ -17,6 +17,7 @@
 import de.ii.xtraplatform.features.domain.Tuple;
 import de.ii.xtraplatform.features.sql.app.SqlQueryTemplates.MetaQueryTemplate;
 import de.ii.xtraplatform.features.sql.app.SqlQueryTemplates.ValueQueryTemplate;
+import de.ii.xtraplatform.features.sql.domain.FeatureProviderSqlData.QueryGeneratorSettings;
 import de.ii.xtraplatform.features.sql.domain.SchemaSql;
 import de.ii.xtraplatform.features.sql.domain.SqlDialect;
 import java.sql.Timestamp;
@@ -42,18 +43,28 @@ public class SqlQueryTemplatesDeriver
   private final FilterEncoderSql filterEncoder;
   private final boolean computeNumberMatched;
   private final boolean computeNumberSkipped;
+  private final String nullOrder;
 
   public SqlQueryTemplatesDeriver(
       SchemaSql queryablesSchema,
       FilterEncoderSql filterEncoder,
       SqlDialect sqlDialect,
       boolean computeNumberMatched,
-      boolean computeNumberSkipped) {
+      boolean computeNumberSkipped,
+      Optional<QueryGeneratorSettings.NullOrder> nullOrder) {
     this.queryablesSchema = queryablesSchema;
     this.sqlDialect = sqlDialect;
     this.filterEncoder = filterEncoder;
     this.computeNumberMatched = computeNumberMatched;
     this.computeNumberSkipped = computeNumberSkipped;
+    this.nullOrder =
+        nullOrder
+            .map(
+                nulls ->
+                    nulls == QueryGeneratorSettings.NullOrder.FIRST
+                        ? " NULLS FIRST"
+                        : " NULLS LAST")
+            .orElse("");
   }
 
   @Override
@@ -252,9 +263,9 @@ private String getTableQuery(
                   index -> {
                     if (index < additionalSortKeys.size()
                         && additionalSortKeys.get(index).getDirection() == Direction.DESCENDING) {
-                      return sortFields.get(index) + " DESC";
+                      return sortFields.get(index) + " DESC" + nullOrder;
                     }
-                    return sortFields.get(index);
+                    return sortFields.get(index) + nullOrder;
                   })
               .filter(sortField -> sortField.startsWith("A."))
               .map(sortField -> sortField.replace("A.", aliasesNested.get(0) + "."))
@@ -282,9 +293,9 @@ private String getTableQuery(
                 index -> {
                   if (index <= additionalSortKeys.size()
                       && additionalSortKeys.get(index - 1).getDirection() == Direction.DESCENDING) {
-                    return index + " DESC";
+                    return index + " DESC" + nullOrder;
                   }
-                  return String.valueOf(index);
+                  return index + nullOrder;
                 })
             .collect(Collectors.joining(","));
 
@@ -434,7 +445,12 @@ private String getOrderBy(List<SortKey> sortKeys) {
       SortKey sortKey = sortKeys.get(i);
 
       orderBy +=
-          CSKEY + "_" + i + (sortKey.getDirection() == Direction.DESCENDING ? " DESC" : "") + ", ";
+          CSKEY
+              + "_"
+              + i
+              + (sortKey.getDirection() == Direction.DESCENDING ? " DESC" : "")
+              + nullOrder
+              + ", ";
     }
 
     orderBy += SKEY;

xtraplatform-features-sql/src/main/java/de/ii/xtraplatform/features/sql/domain/FeatureProviderSql.java

@@ -521,7 +521,8 @@ protected boolean onStartup() throws InterruptedException {
                                           filterEncoder,
                                           sqlDialect,
                                           getData().getQueryGeneration().getComputeNumberMatched(),
-                                          true)))
+                                          true,
+                                          getData().getQueryGeneration().getNullOrder())))
                           .collect(Collectors.toList()));
                 })
             .collect(ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue));
@@ -544,7 +545,8 @@ protected boolean onStartup() throws InterruptedException {
                                         filterEncoder,
                                         sqlDialect,
                                         getData().getQueryGeneration().getComputeNumberMatched(),
-                                        false)))))
+                                        false,
+                                        getData().getQueryGeneration().getNullOrder())))))
             .collect(ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue));
 
     this.queryTransformer =

xtraplatform-features-sql/src/main/java/de/ii/xtraplatform/features/sql/domain/FeatureProviderSqlData.java

@@ -138,6 +138,11 @@ public ImmutableFeatureProviderSqlData.Builder fillRequiredFieldsWithPlaceholder
   @JsonDeserialize(builder = ImmutableQueryGeneratorSettings.Builder.class)
   interface QueryGeneratorSettings {
 
+    enum NullOrder {
+      FIRST,
+      LAST
+    }
+
     @DocIgnore
     @Value.Default
     default int getChunkSize() {
@@ -159,6 +164,22 @@ default boolean getComputeNumberMatched() {
       return true;
     }
 
+    /**
+     * @langEn If no value is provided, the sort order of the underlying feature provider (typically
+     *     `last` for ascending and `first` for descending) is used. `last` or `first` can be used
+     *     to force a specific sort order, if some rows have null values.
+     * @langDe Ohne Angabe wird die Sortierreihenfolge des zugrunde liegenden Feature-Providers
+     *     verwendet (normalerweise `last` für aufsteigend und `first` für absteigend). `last` oder
+     *     `first` kann verwendet werden, um eine bestimmte Sortierreihenfolge für Spalten mit
+     *     Nullwerten zu erzwingen.
+     * @default -
+     * @since v4.3
+     */
+    @Value.Default
+    default Optional<NullOrder> getNullOrder() {
+      return Optional.empty();
+    }
+
     // TODO
     @DocIgnore
     @Value.Default

xtraplatform-features-sql/src/test/groovy/de/ii/xtraplatform/features/sql/app/SqlQueryTemplatesDeriverSpec.groovy

@@ -29,9 +29,9 @@ class SqlQueryTemplatesDeriverSpec extends Specification {
     @Shared
     FilterEncoderSql filterEncoder = new FilterEncoderSql(OgcCrs.CRS84, new SqlDialectPgis(), null, null, new CqlImpl(), null)
     @Shared
-    SqlQueryTemplatesDeriver td = new SqlQueryTemplatesDeriver(null, filterEncoder, new SqlDialectPgis(), true, false)
+    SqlQueryTemplatesDeriver td = new SqlQueryTemplatesDeriver(null, filterEncoder, new SqlDialectPgis(), true, false, Optional.empty())
     @Shared
-    SqlQueryTemplatesDeriver tdNoNm = new SqlQueryTemplatesDeriver(null, filterEncoder, new SqlDialectPgis(), false, false)
+    SqlQueryTemplatesDeriver tdNoNm = new SqlQueryTemplatesDeriver(null, filterEncoder, new SqlDialectPgis(), false, false, Optional.empty())
 
     @Shared
     QuerySchemaDeriver schemaDeriver