Add JSON writer to Scala Custom

src/scala/src/main/scala/Custom.scala

@@ -2,6 +2,7 @@ package solutions.bitbadger.documents.scala
 
 import solutions.bitbadger.documents.{Configuration, Parameter}
 
+import java.io.PrintWriter
 import java.sql.{Connection, ResultSet}
 import scala.reflect.ClassTag
 import scala.util.Using
@@ -107,6 +108,60 @@ object Custom:
   def jsonArray(query: String, mapFunc: ResultSet => String): String =
     jsonArray(query, Nil, mapFunc)
 
+  /**
+   * Execute a query that writes a JSON array of results to the given `PrintWriter`
+   *
+   * @param query      The query to retrieve the results
+   * @param parameters Parameters to use for the query
+   * @param writer     The writer to which the results should be written
+   * @param conn       The connection over which the query should be executed
+   * @param mapFunc    The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeJsonArray(query: String, parameters: Seq[Parameter[?]], writer: PrintWriter, conn: Connection,
+                     mapFunc: ResultSet => String): Unit =
+    Using(Parameters.apply(conn, query, parameters)) { stmt => Results.writeJsonArray(writer, stmt, mapFunc) }
+
+  /**
+   * Execute a query that returns a JSON array of results
+   *
+   * @param query   The query to retrieve the results
+   * @param writer  The writer to which the results should be written
+   * @param conn    The connection over which the query should be executed
+   * @param mapFunc The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeJsonArray(query: String, conn: Connection, writer: PrintWriter, mapFunc: ResultSet => String): Unit =
+    writeJsonArray(query, Nil, writer, conn, mapFunc)
+
+  /**
+   * Execute a query that returns a JSON array of results (creates connection)
+   *
+   * @param query      The query to retrieve the results
+   * @param parameters Parameters to use for the query
+   * @param writer     The writer to which the results should be written
+   * @param mapFunc    The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeJsonArray(query: String, parameters: Seq[Parameter[?]], writer: PrintWriter,
+                     mapFunc: ResultSet => String): Unit =
+    Using(Configuration.dbConn()) { conn => writeJsonArray(query, parameters, writer, conn, mapFunc) }
+
+  /**
+   * Execute a query that returns a JSON array of results (creates connection)
+   *
+   * @param query   The query to retrieve the results
+   * @param writer  The writer to which the results should be written
+   * @param mapFunc The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeJsonArray(query: String, writer: PrintWriter, mapFunc: ResultSet => String): Unit =
+    writeJsonArray(query, Nil, writer, mapFunc)
+
   /**
    * Execute a query that returns one or no results
    *

src/scala/src/main/scala/Results.scala

@@ -3,6 +3,7 @@ package solutions.bitbadger.documents.scala
 import solutions.bitbadger.documents.DocumentException
 import solutions.bitbadger.documents.java.Results as CoreResults
 
+import java.io.PrintWriter
 import java.sql.{PreparedStatement, ResultSet, SQLException}
 import scala.collection.mutable.ListBuffer
 import scala.reflect.ClassTag
@@ -47,9 +48,8 @@ object Results:
     try
       val buffer = ListBuffer[Doc]()
       Using(stmt.executeQuery()) { rs =>
-        while (rs.next()) {
+        while rs.next() do
           buffer.append(mapFunc(rs, tag))
-        }
       }
       buffer.toList
     catch
@@ -107,12 +107,37 @@ object Results:
     try
       val results = StringBuilder("[")
       Using(stmt.executeQuery()) { rs =>
-        while (rs.next()) {
+        while rs.next() do
           if (results.length > 2) results.append(",")
           results.append(mapFunc(rs))
-        }
       }
       results.append("]").toString()
     catch
-      case ex: SQLException => 
-        throw DocumentException("Error retrieving documents from query: ${ex.message}", ex)
+      case ex: SQLException => throw DocumentException("Error retrieving documents from query: ${ex.message}", ex)
+
+  /**
+   * Write a JSON array of items for the results of the given command to the given `PrintWriter`, using the specified
+   * mapping function
+   *
+   * @param writer  The writer for the results of the query
+   * @param stmt    The prepared statement to execute
+   * @param mapFunc The mapping function from data reader to JSON text
+   * @return A string with a JSON array of documents from the query's result
+   * @throws DocumentException If there is a problem executing the query (unchecked)
+   */
+  def writeJsonArray(writer: PrintWriter, stmt: PreparedStatement, mapFunc: ResultSet => String): Unit =
+    try
+      writer.write("[")
+      Using(stmt.executeQuery()) { rs =>
+        var isFirst = true
+        while rs.next() do
+          if isFirst then
+            isFirst = false
+          else
+            writer.write(",")
+          writer.write(mapFunc(rs))
+      }
+      writer.write("]")
+    catch
+      case ex: SQLException => throw DocumentException("Error writing documents from query: ${ex.message}", ex)
+

src/scala/src/main/scala/extensions/package.scala

@@ -3,6 +3,7 @@ package solutions.bitbadger.documents.scala.extensions
 import solutions.bitbadger.documents.{DocumentIndex, Field, FieldMatch, Parameter}
 import solutions.bitbadger.documents.scala.*
 
+import java.io.PrintWriter
 import java.sql.{Connection, ResultSet}
 import scala.reflect.ClassTag
 
@@ -58,6 +59,32 @@ extension (conn: Connection)
   def customJsonArray(query: String, mapFunc: ResultSet => String): String =
     Custom.jsonArray(query, mapFunc)
 
+  /**
+   * Execute a query that writes a JSON array of results to the given `PrintWriter`
+   *
+   * @param query      The query to retrieve the results
+   * @param parameters Parameters to use for the query
+   * @param writer     The writer to which the results should be written
+   * @param mapFunc    The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeCustomJsonArray(query: String, parameters: Seq[Parameter[?]], writer: PrintWriter,
+                           mapFunc: ResultSet => String): Unit =
+    Custom.writeJsonArray(query, parameters, writer, conn, mapFunc)
+
+  /**
+   * Execute a query that writes a JSON array of results to the given `PrintWriter`
+   *
+   * @param query   The query to retrieve the results
+   * @param writer  The writer to which the results should be written
+   * @param mapFunc The mapping function to extract the JSON from the query
+   * @return A JSON array of results for the given query
+   * @throws DocumentException If parameters are invalid
+   */
+  def writeCustomJsonArray(query: String, writer: PrintWriter, mapFunc: ResultSet => String): Unit =
+    Custom.writeJsonArray(query, writer, mapFunc)
+
   /**
    * Execute a query that returns one or no results
    *

src/scala/src/test/scala/integration/CustomFunctions.scala

@@ -7,6 +7,7 @@ import solutions.bitbadger.documents.scala.extensions.*
 import solutions.bitbadger.documents.scala.tests.TEST_TABLE
 import solutions.bitbadger.documents.{Configuration, Field, Parameter, ParameterType}
 
+import java.io.{PrintWriter, StringWriter}
 import scala.jdk.CollectionConverters.*
 
 object CustomFunctions:
@@ -29,19 +30,43 @@ object CustomFunctions:
 
   def jsonArraySingle(db: ThrowawayDatabase): Unit =
     db.conn.insert(TEST_TABLE, ArrayDocument("one", "2" :: "3" :: Nil))
-    assertEquals(JsonFunctions.maybeJsonB("[{\"id\":\"one\",\"values\":[\"2\",\"3\"]}]"),
+    assertEquals(JsonFunctions.maybeJsonB("""[{"id":"one","values":["2","3"]}]"""),
       db.conn.customJsonArray(FindQuery.all(TEST_TABLE), Nil, Results.jsonFromData),
       "A single document list was not represented correctly")
   
   def jsonArrayMany(db: ThrowawayDatabase): Unit =
     ArrayDocument.testDocuments.foreach { doc => db.conn.insert(TEST_TABLE, doc) }
-    assertEquals(JsonFunctions.maybeJsonB("[{\"id\":\"first\",\"values\":[\"a\",\"b\",\"c\"]},"
-        + "{\"id\":\"second\",\"values\":[\"c\",\"d\",\"e\"]},"
-        + "{\"id\":\"third\",\"values\":[\"x\",\"y\",\"z\"]}]"),
+    assertEquals(JsonFunctions.maybeJsonB("""[{"id":"first","values":["a","b","c"]},"""
+        + """{"id":"second","values":["c","d","e"]},{"id":"third","values":["x","y","z"]}]"""),
       db.conn.customJsonArray(FindQuery.all(TEST_TABLE) + QueryUtils.orderBy((Field.named("id") :: Nil).asJava), Nil,
         Results.jsonFromData),
       "A multiple document list was not represented correctly")
 
+  def writeJsonArrayEmpty(db: ThrowawayDatabase): Unit =
+    assertEquals(0L, db.conn.countAll(TEST_TABLE), "The test table should be empty")
+    val output = StringWriter()
+    val writer = PrintWriter(output)
+    db.conn.writeCustomJsonArray(FindQuery.all(TEST_TABLE), Nil, writer, Results.jsonFromData)
+    assertEquals("[]", output.toString, "An empty list was not represented correctly")
+
+  def writeJsonArraySingle(db: ThrowawayDatabase): Unit =
+    db.conn.insert(TEST_TABLE, ArrayDocument("one", "2" :: "3" :: Nil))
+    val output = StringWriter()
+    val writer = PrintWriter(output)
+    db.conn.writeCustomJsonArray(FindQuery.all(TEST_TABLE), Nil, writer, Results.jsonFromData)
+    assertEquals(JsonFunctions.maybeJsonB("""[{"id":"one","values":["2","3"]}]"""), output.toString,
+      "A single document list was not represented correctly")
+
+  def writeJsonArrayMany(db: ThrowawayDatabase): Unit =
+    ArrayDocument.testDocuments.foreach { doc => db.conn.insert(TEST_TABLE, doc) }
+    val output = StringWriter()
+    val writer = PrintWriter(output)
+    db.conn.writeCustomJsonArray(FindQuery.all(TEST_TABLE) + QueryUtils.orderBy((Field.named("id") :: Nil).asJava), Nil,
+      writer, Results.jsonFromData)
+    assertEquals(JsonFunctions.maybeJsonB("""[{"id":"first","values":["a","b","c"]},"""
+        + """{"id":"second","values":["c","d","e"]},{"id":"third","values":["x","y","z"]}]"""),
+      output.toString, "A multiple document list was not represented correctly")
+
   def singleNone(db: ThrowawayDatabase): Unit =
     assertTrue(db.conn.customSingle[JsonDocument](FindQuery.all(TEST_TABLE), Results.fromData).isEmpty,
       "There should not have been a document returned")

src/scala/src/test/scala/integration/PostgreSQLCustomIT.scala

@@ -32,6 +32,21 @@ class PostgreSQLCustomIT:
   def jsonArrayMany(): Unit =
     Using(PgDB()) { db => CustomFunctions.jsonArrayMany(db) }
 
+  @Test
+  @DisplayName("writeJsonArray succeeds with empty array")
+  def writeJsonArrayEmpty(): Unit =
+    Using(PgDB()) { db => CustomFunctions.writeJsonArrayEmpty(db) }
+
+  @Test
+  @DisplayName("writeJsonArray succeeds with a single-item array")
+  def writeJsonArraySingle(): Unit =
+    Using(PgDB()) { db => CustomFunctions.writeJsonArraySingle(db) }
+
+  @Test
+  @DisplayName("writeJsonArray succeeds with a multi-item array")
+  def writeJsonArrayMany(): Unit =
+    Using(PgDB()) { db => CustomFunctions.writeJsonArrayMany(db) }
+
   @Test
   @DisplayName("single succeeds when document not found")
   def singleNone(): Unit =

src/scala/src/test/scala/integration/SQLiteCustomIT.scala

@@ -32,6 +32,21 @@ class SQLiteCustomIT:
   def jsonArrayMany(): Unit =
     Using(SQLiteDB()) { db => CustomFunctions.jsonArrayMany(db) }
 
+  @Test
+  @DisplayName("writeJsonArray succeeds with empty array")
+  def writeJsonArrayEmpty(): Unit =
+    Using(SQLiteDB()) { db => CustomFunctions.writeJsonArrayEmpty(db) }
+
+  @Test
+  @DisplayName("writeJsonArray succeeds with a single-item array")
+  def writeJsonArraySingle(): Unit =
+    Using(SQLiteDB()) { db => CustomFunctions.writeJsonArraySingle(db) }
+
+  @Test
+  @DisplayName("writeJsonArray succeeds with a multi-item array")
+  def writeJsonArrayMany(): Unit =
+    Using(SQLiteDB()) { db => CustomFunctions.writeJsonArrayMany(db) }
+
   @Test
   @DisplayName("single succeeds when document not found")
   def singleNone(): Unit =