Atlas client: Create a type, where attribute type is a list

In this post, I am going to explain how can we define an attribute that takes list of string.

 

To define an attribute with type list, you should specify

a.   typeName as array<string>

b.   cardinality should be set to LIST like below.

 

"attributeDefs": [
    {
      "name": "hobbies",
      "typeName": "array<string>",
      "isOptional": false,
      "cardinality": "LIST",
      "valuesMinCount": 1,
      "valuesMaxCount": 2147483647,
      "isUnique": false,
      "isIndexable": true,
      "includeInNotification": false,
      "searchWeight": -1
    }
  ]

 

Find the below working application.

 

Create atlas-application.properties file under src/main/resources folder.

 

atlas-application.properties

 

atlas.client.readTimeoutMSecs=30000
atlas.client.connectTimeoutMSecs=30000

 

Define AttributeWithListOfStrings class.

 

AttributeWithListOfStrings.java

package com.sample.app.attributes;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import org.apache.atlas.AtlasClientV2;
import org.apache.atlas.AtlasServiceException;
import org.apache.atlas.model.instance.AtlasEntity;
import org.apache.atlas.model.typedef.AtlasEntityDef;
import org.apache.atlas.model.typedef.AtlasTypesDef;
import org.apache.atlas.model.typedef.AtlasStructDef.AtlasAttributeDef;

import com.fasterxml.jackson.core.JsonProcessingException;

public class AttributeWithListOfStrings {

	private static final String TYPE_NAME = "DemoType2";

	private static void createType(AtlasClientV2 atlasClient) throws AtlasServiceException {
		AtlasAttributeDef attributeDef1 = new AtlasAttributeDef();
		attributeDef1.setName("hobbies");
		attributeDef1.setTypeName("array<string>");
		attributeDef1.setCardinality(AtlasAttributeDef.Cardinality.LIST);
		attributeDef1.setIsIndexable(true);
		attributeDef1.setIsUnique(false);

		AtlasEntityDef atlasEntityDef = new AtlasEntityDef();
		atlasEntityDef.setName(TYPE_NAME);
		atlasEntityDef.setCreatedBy("Krishna");
		atlasEntityDef.setUpdatedBy("krishna");
		atlasEntityDef.setDescription("Represent a laptoo specification");
		atlasEntityDef.setAttributeDefs(Arrays.asList(attributeDef1));

		Set<String> superTypes = new HashSet<>();
		superTypes.add("DataSet");
		atlasEntityDef.setSuperTypes(superTypes);

		AtlasTypesDef atlasTypesDef = new AtlasTypesDef();

		atlasTypesDef.getEntityDefs().add(atlasEntityDef);

		atlasClient.createAtlasTypeDefs(atlasTypesDef);
	}

	private static void createEntity(AtlasClientV2 atlasClient) throws AtlasServiceException {

		AtlasEntity atlasEntity = new AtlasEntity();

		atlasEntity.setTypeName(TYPE_NAME);

		atlasEntity.setAttribute("hobbies", Arrays.asList("football", "cricket", "football"));

		// Following are the mandatory attributes
		atlasEntity.setAttribute("qualifiedName", "AttributeWithListOfStrings_DEMO1");
		atlasEntity.setAttribute("name", "AttributeWithListOfStrings_DEMO1");

		AtlasEntity.AtlasEntityWithExtInfo atlasEntityWithExtInfo = new AtlasEntity.AtlasEntityWithExtInfo();
		atlasEntityWithExtInfo.setEntity(atlasEntity);

		atlasClient.createEntity(atlasEntityWithExtInfo);
	}

	public static void main(String[] args) throws AtlasServiceException, JsonProcessingException {

		AtlasClientV2 atlasClient = new AtlasClientV2(new String[] { "http://localhost:21000" },
				new String[] { "admin", "admin" });

		createType(atlasClient);
		createEntity(atlasClient);

	}
}

 

Login to Atlas UI and query for the type ‘DemoType2’.

 

  

Navigate to the entity ‘AttributeWithListOfStrings_DEMO1’ to see all the properties.

 

 

As you see above image, hobby ‘football’ is repeated twice. We can solve this problem by making the attribute cardinality as SET. I will explain this in my next post.

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