Add Nested Entities as Fields

This example will show you how you can create nested entities using RecordFieldDef.

Java code listing

package com.northconcepts.datapipeline.foundations.examples.schema;

import com.northconcepts.datapipeline.core.FieldType;
import com.northconcepts.datapipeline.foundations.schema.EntityDef;
import com.northconcepts.datapipeline.foundations.schema.NumericFieldDef;
import com.northconcepts.datapipeline.foundations.schema.PrimaryKeyType;
import com.northconcepts.datapipeline.foundations.schema.RecordFieldDef;
import com.northconcepts.datapipeline.foundations.schema.SchemaDef;
import com.northconcepts.datapipeline.foundations.schema.TextFieldDef;

public class AddNestedEntitiesAsFields {

    public static void main(String[] args) {
        SchemaDef schema = new SchemaDef("E-Commerce Schema");

        schema.addEntity(new EntityDef("orders")
                .addField(new NumericFieldDef("order_id", FieldType.LONG).setPrimaryKeyPosition(0).setPrimaryKeyType(PrimaryKeyType.TABLE))
                .addField(new RecordFieldDef("customer", "customers"))
                .addField(new TextFieldDef("product_name", FieldType.STRING))
                .addField(new NumericFieldDef("quantity", FieldType.LONG))
                );

        schema.addEntity(new EntityDef("customers")
                .addField(new NumericFieldDef("customer_id", FieldType.LONG).setPrimaryKeyPosition(0).setPrimaryKeyType(PrimaryKeyType.AUTO))
                .addField(new TextFieldDef("customer_name", FieldType.STRING))
                .addField(new TextFieldDef("address", FieldType.STRING))
                );

        System.out.println("=========================================================");
        System.out.println(schema.toXml());
        System.out.println("=========================================================");
    }
}

Code walkthrough

1. Create a SchemaDef named E-Commerce Schema with two entities.
2. One entity is customers.
3. Another entity is orders which has a RecordFieldDef named, customer. This is a nested entity.
4. Print this schema as XML.

Console Output

=========================================================
<schema name="E-Commerce Schema">
  <entities>
    <entity addMissingOptionalFields="false" allowExtraFieldsInMapping="true" allowExtraFieldsInValidation="true" name="orders">
      <fields>
        <field array="false" name="order_id" primaryKeyPosition="0" primaryKeyType="TABLE" required="false" strictArrays="true" type="LONG"/>
        <field array="false" name="customer" referencedEntityName="customers" required="false" strictArrays="true" type="RECORD"/>
        <field allowBlank="true" array="false" name="product_name" required="false" strictArrays="true" type="STRING"/>
        <field array="false" name="quantity" required="false" strictArrays="true" type="LONG"/>
      </fields>
    </entity>
    <entity addMissingOptionalFields="false" allowExtraFieldsInMapping="true" allowExtraFieldsInValidation="true" name="customers">
      <fields>
        <field array="false" name="customer_id" primaryKeyPosition="0" primaryKeyType="AUTO" required="false" strictArrays="true" type="LONG"/>
        <field allowBlank="true" array="false" name="customer_name" required="false" strictArrays="true" type="STRING"/>
        <field allowBlank="true" array="false" name="address" required="false" strictArrays="true" type="STRING"/>
      </fields>
    </entity>
  </entities>
</schema>

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