Use consistent build pattern

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/select/MultiSelectDSL.java

@@ -19,6 +19,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
+import java.util.Optional;
 
 import org.jetbrains.annotations.NotNull;
 import org.mybatis.dynamic.sql.SortSpecification;
@@ -74,24 +75,20 @@ public FetchFirstFinisher fetchFirst(long fetchFirstRows) {
     @NotNull
     @Override
     public MultiSelectModel build() {
-        MultiSelectModel.Builder builder = new MultiSelectModel.Builder()
+        return new MultiSelectModel.Builder()
                 .withInitialSelect(initialSelect)
                 .withUnionQueries(unionQueries)
-                .withOrderByModel(orderByModel);
-
-        addPagingModel(builder);
-        return builder.build();
+                .withOrderByModel(orderByModel)
+                .withPagingModel(buildPagingModel().orElse(null))
+                .build();
     }
 
-    private void addPagingModel(MultiSelectModel.Builder builder) {
-        if (limit != null || offset != null || fetchFirstRows != null) {
-            // add paging model if any values set
-            builder.withPagingModel(new PagingModel.Builder()
-                    .withLimit(limit)
-                    .withOffset(offset)
-                    .withFetchFirstRows(fetchFirstRows)
-                    .build());
-        }
+    private Optional<PagingModel> buildPagingModel() {
+        return new PagingModel.Builder()
+                .withLimit(limit)
+                .withOffset(offset)
+                .withFetchFirstRows(fetchFirstRows)
+                .build();
     }
 
     public class LimitFinisher implements Buildable<MultiSelectModel> {

src/main/java/org/mybatis/dynamic/sql/select/PagingModel.java

@@ -62,8 +62,12 @@ public Builder withFetchFirstRows(Long fetchFirstRows) {
             return this;
         }
 
-        public PagingModel build() {
-            return new PagingModel(this);
+        public Optional<PagingModel> build() {
+            if (limit == null && offset == null && fetchFirstRows == null) {
+                return Optional.empty();
+            }
+
+            return Optional.of(new PagingModel(this));
         }
     }
 }

src/main/java/org/mybatis/dynamic/sql/select/SelectDSL.java

@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -130,10 +131,11 @@ public SelectDSL<R> configureStatement(Consumer<StatementConfiguration> consumer
     @NotNull
     @Override
     public R build() {
-        SelectModel.Builder builder = SelectModel.withQueryExpressions(buildModels())
-                .withOrderByModel(orderByModel);
-        addPagingModel(builder);
-        return adapterFunction.apply(builder.build());
+        SelectModel selectModel = SelectModel.withQueryExpressions(buildModels())
+                .withOrderByModel(orderByModel)
+                .withPagingModel(buildPagingModel().orElse(null))
+                .build();
+        return adapterFunction.apply(selectModel);
     }
 
     private List<QueryExpressionModel> buildModels() {
@@ -142,15 +144,12 @@ private List<QueryExpressionModel> buildModels() {
                 .collect(Collectors.toList());
     }
 
-    private void addPagingModel(SelectModel.Builder builder) {
-        if (limit != null || offset != null || fetchFirstRows != null) {
-            // add paging model if any values set
-            builder.withPagingModel(new PagingModel.Builder()
-                    .withLimit(limit)
-                    .withOffset(offset)
-                    .withFetchFirstRows(fetchFirstRows)
-                    .build());
-        }
+    private Optional<PagingModel> buildPagingModel() {
+        return new PagingModel.Builder()
+                .withLimit(limit)
+                .withOffset(offset)
+                .withFetchFirstRows(fetchFirstRows)
+                .build();
     }
 
     public class LimitFinisher implements Buildable<R> {

src/test/java/org/mybatis/dynamic/sql/InvalidSQLTest.java

@@ -47,7 +47,7 @@
 import org.mybatis.dynamic.sql.select.join.JoinModel;
 import org.mybatis.dynamic.sql.select.join.JoinSpecification;
 import org.mybatis.dynamic.sql.select.join.JoinType;
-import org.mybatis.dynamic.sql.select.render.PagingModelRenderer;
+import org.mybatis.dynamic.sql.select.render.FetchFirstPagingModelRenderer;
 import org.mybatis.dynamic.sql.select.render.SelectStatementProvider;
 import org.mybatis.dynamic.sql.update.UpdateModel;
 import org.mybatis.dynamic.sql.util.InternalError;
@@ -238,16 +238,15 @@ void testMissingMessage() {
 
     @Test
     void testInvalidPagingModel() {
-        PagingModel pagingModel = new PagingModel.Builder().build();
+        Optional<PagingModel> pagingModel = new PagingModel.Builder().withLimit(22L).build();
 
         RenderingContext renderingContext = RenderingContext
                 .withRenderingStrategy(RenderingStrategies.MYBATIS3)
                 .build();
 
-        PagingModelRenderer renderer = new PagingModelRenderer.Builder()
-                .withPagingModel(pagingModel)
-                .withRenderingContext(renderingContext)
-                .build();
+        assertThat(pagingModel).isPresent();
+
+        FetchFirstPagingModelRenderer renderer = new FetchFirstPagingModelRenderer(renderingContext, pagingModel.get());
 
         assertThatExceptionOfType(InvalidSqlException.class)
                 .isThrownBy(renderer::render)