> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Use custom types
# Using Custom Types with DirectQuery
When using DirectQuery, Atoti retrieves data from the remote database.
DirectQuery has sensible defaults to read the different data types from the remote database into common data types.
However, in some situations where the remote type is complex or one wishes to customize the resulting type,
it is possible to adjust it.
This guide describes how to do this.
## Define the Custom Type
First, we define two custom types: they are simple wrappers around a String and a double.
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
@Data
public static class CustomShop {
final String shopName;
public static CustomShop getDefaultValue() {
return new CustomShop("N/A");
}
@Override
public String toString() {
return "CustomShop(shopName=" + this.shopName + ")";
}
}
@Data
public static class CustomPrice {
final double price;
public static CustomPrice getDefaultValue() {
return new CustomPrice(0.0);
}
@Override
public String toString() {
return "CustomPrice(price=" + this.price + ")";
}
}
```
## Adjust the database schema
We customize the field in the "SALES" table definition.
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(PROJECT_ID, "tutorial", "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop(value.toString())));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new ClickhouseTableId("TUTORIAL", "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop(value.toString())));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(CATALOG_NAME, TUTORIAL_SCHEMA_NAME, "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
shopField.toBuilder()
.type(
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop((String) value)))
.build();
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, SCHEMA_NAME, "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop(value.toString())));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, "TUTORIAL", "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop(value.toString())));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(TEST_DATABASE_NAME, TUTORIAL_SCHEMA_NAME, "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.ofObject(CustomShop.getDefaultValue()),
CustomReaderDescription.fromObjectData(value -> new CustomShop((String) value)));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(TEST_DATABASE_NAME, TUTORIAL_SCHEMA_NAME, "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop((String) value)));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription salesTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, "TUTORIAL", "SALES"));
final FieldDescription shopField = (FieldDescription) salesTable.getField("SHOP");
final AFieldDescription updatedShopField =
FieldDescription.changeFieldType(
shopField,
FieldType.builder()
.dataClass(CustomShop.class)
.defaultValue(CustomShop.getDefaultValue())
.build(),
CustomReaderDescription.fromObjectData(value -> new CustomShop(value.toString())));
final TableDescription updatedSalesTable =
TableDescriptionUtils.updateField(salesTable, "SHOP", updatedShopField);
```
If the column contains a primitive types (such as `int` or `double`), it is more efficient to
use a specific API.
We use such an API to customize the "PRODUCTS" table definition:
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new SqlTableId(PROJECT_ID, "tutorial", "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
Note that ClickHouse has no specific API, as the generic one already caters to primitives.
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new ClickhouseTableId("TUTORIAL", "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.contentType(ContentType.OBJECT)
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new SqlTableId(CATALOG_NAME, TUTORIAL_SCHEMA_NAME, "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final FieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.contentType(ContentType.OBJECT)
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, SCHEMA_NAME, "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.contentType(ContentType.OBJECT)
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, SCHEMA_NAME, "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(
new SqlTableId(TEST_DATABASE_NAME, TUTORIAL_SCHEMA_NAME, "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(
new SqlTableId(TEST_DATABASE_NAME, TUTORIAL_SCHEMA_NAME, "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final TableDescription productsTable =
discoverer.discoverTable(new SqlTableId(DATABASE_NAME, "TUTORIAL", "PRODUCTS"));
final FieldDescription priceField = (FieldDescription) productsTable.getField("PURCHASE_PRICE");
final AFieldDescription updatedPriceField =
FieldDescription.changeFieldType(
priceField,
FieldType.builder()
.contentType(ContentType.OBJECT)
.dataClass(CustomPrice.class)
.defaultValue(CustomPrice.getDefaultValue())
.build(),
CustomReaderDescription.fromDoubleData(CustomPrice::new));
final TableDescription updatedProductsTable =
TableDescriptionUtils.updateField(productsTable, "PURCHASE_PRICE", updatedPriceField);
```
The schema and database are created as usual:
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final JoinDescription join =
JoinDescription.builder()
.name("SALES_TO_PRODUCTS")
.sourceTableName("SALES")
.targetTableName("PRODUCTS")
.fieldMappings(Set.of(new FieldMapping("PRODUCT", "PRODUCT_ID")))
.build();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final SchemaDescription schema =
SchemaDescription.builder()
.externalTables(List.of(updatedSalesTable, updatedProductsTable))
.externalJoins(List.of(join))
.build();
```
## Run a query
We can run a simple query, to check it works:
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app =
Application.builder(connector)
.schema(schema)
.databaseSettings(BigqueryDatabaseSettings.defaults())
.build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getMasterHead();
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final Application app = Application.builder(connector).schema(schema).build();
final IDatabaseVersion databaseVersion = app.getDatabase().getHead(MASTER_BRANCH_NAME);
```
```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
final ListQuery query =
databaseVersion
.getQueryManager()
.listQuery()
.forTable("SALES")
.withCondition(BaseConditions.equal(FieldPath.of("SALE_ID"), "S0017"))
.withAliasedFields(
AliasedField.fromFieldName("SALE_ID"),
AliasedField.fromFieldName("SHOP"),
AliasedField.create(
"PURCHASE_PRICE", FieldPath.of("SALES_TO_PRODUCTS", "PURCHASE_PRICE")))
.toQuery();
final ICursor res = databaseVersion.getQueryRunner().listQuery(query).run();
assertThat(res.next()).isTrue();
final IRecordReader recordReader = res.getRecord();
System.out.println(recordReader.read(1)); // Printed CustomShop(shopName=shop_3)
System.out.println(recordReader.read(2)); // Printed CustomPrice(price=38.0)
```
## Conclusion
That's it. Every query on the 'SHOP' (resp. 'PURCHASE\_PRICE') column will generate an Object of class
CustomShop (resp. CustomPrice).