Update the error message if column doesn't exist in projection

src/main/java/io/stargate/sgv2/jsonapi/exception/ProjectionException.java

@@ -14,7 +14,8 @@ public ProjectionException(ErrorInstance errorInstance) {
   }
 
   public enum Code implements ErrorCode<ProjectionException> {
-    UNSUPPORTED_COLUMN_TYPES;
+    UNSUPPORTED_COLUMN_TYPES,
+    UNKNOWN_TABLE_COLUMNS;
 
     private final ErrorTemplate<ProjectionException> template;
 

src/main/java/io/stargate/sgv2/jsonapi/service/operation/tables/TableProjection.java

@@ -85,8 +85,15 @@ public static <CmdT extends Projectable> TableProjection fromDefinition(
 
     // TODO: A table can't be with empty columns. Think a redundant check.
     if (columns.isEmpty()) {
-      throw ErrorCodeV1.UNSUPPORTED_PROJECTION_DEFINITION.toApiException(
-          "did not include any Table columns");
+      throw ProjectionException.Code.UNKNOWN_TABLE_COLUMNS.get(
+          errVars(
+              table,
+              map -> {
+                map.put("allColumns", errFmtApiColumnDef(table.apiTableDef().allColumns()));
+                map.put(
+                    "unknownColumns",
+                    command.tableProjectionDefinition().getColumnNames().toString());
+              }));
     }
 
     // result set has ColumnDefinitions not ColumnMetadata kind of weird

src/main/java/io/stargate/sgv2/jsonapi/service/projection/TableProjectionDefinition.java

@@ -30,6 +30,15 @@ private TableProjectionDefinition(boolean inclusion, List<String> columnNames) {
     this.columnNames = columnNames;
   }
 
+  /**
+   * Return the column defined in the projection.
+   *
+   * @return a new {@code ArrayList} containing the column names.
+   */
+  public List<String> getColumnNames() {
+    return new ArrayList<>(columnNames);
+  }
+
   public static TableProjectionDefinition createFromDefinition(JsonNode projectionDefinition) {
     // First special case: "simple" default projection; "include all"
     if (projectionDefinition == null || projectionDefinition.isEmpty()) {

src/main/resources/errors.yaml

@@ -619,6 +619,17 @@ request-errors:
       
       Resend the command using only supported column types.
 
+  - scope: PROJECTION
+    code: UNKNOWN_TABLE_COLUMNS
+    title: Columns in the projection are not defined in the table schema
+    body: |-
+      Only columns defined in the table schema can be included in the projection.
+      
+      The table ${keyspace}.${table} defines the columns: ${allColumns}.
+      The projection included the following unknown columns: ${unknownColumns}.
+      
+      ${SNIPPET.RESEND_USING_ONLY_DEFINED_COLUMNS}
+
   # ================================================================================================================
   # Family: REQUEST         Scope: SCHEMA
   # ================================================================================================================

src/test/java/io/stargate/sgv2/jsonapi/api/v1/tables/ProjectionSchemaIntegrationTest.java

@@ -8,6 +8,7 @@
 import io.stargate.sgv2.jsonapi.api.model.command.CommandName;
 import io.stargate.sgv2.jsonapi.api.v1.util.DataApiResponseValidator;
 import io.stargate.sgv2.jsonapi.api.v1.util.scenarios.AllScalarTypesTableScenario;
+import io.stargate.sgv2.jsonapi.exception.ProjectionException;
 import io.stargate.sgv2.jsonapi.fixtures.types.ApiDataTypesForTesting;
 import io.stargate.sgv2.jsonapi.service.schema.tables.ApiColumnDefContainer;
 import io.stargate.sgv2.jsonapi.service.schema.tables.ApiDataTypeDefs;
@@ -143,6 +144,19 @@ public void findManyProjectionMissingColumns() {
         .doesNotHaveProjectionSchemaWith("MISSING_COLUMN");
   }
 
+  @Test
+  public void findProjectionUnknownColumns() {
+
+    // Select a column that does not exist, should not be in the projection schema
+    assertTableCommand(keyspaceName, TABLE_NAME)
+        .templated()
+        .find(Map.of("id", "row-1"), List.of("FAKE2", "FAKE1"), Map.of(), Map.of())
+        .hasSingleApiError(
+            ProjectionException.Code.UNKNOWN_TABLE_COLUMNS,
+            ProjectionException.class,
+            "The projection included the following unknown columns: [FAKE2, FAKE1]");
+  }
+
   private DataApiResponseValidator assertProjectionSchema(
       DataApiResponseValidator validator, ApiColumnDefContainer columns) {
     columns.values().forEach(validator::hasProjectionSchemaWith);