SpellExample.java

package com.fauna.learn;

import com.faunadb.client.FaunaClient;
import com.faunadb.client.query.Expr;
import com.faunadb.client.types.Value;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Optional;

import static com.faunadb.client.query.Language.*;

/**
 * Run the example in maven using:
 *
 * mvn compile exec:java -Dexec.mainClass="com.fauna.learn.SpellExample"
 */
public class SpellExample {


    public static void main(String[] args) throws Exception {
        /*
         * Create an admin connection to FaunaDB.
         *
         * If you are using the FaunaDB-Cloud version:
         *  - remove the 'withEndpoint' line below
         *  - substitute "secret" for your authentication key's secret
         */
        FaunaClient adminClient = FaunaClient.builder()
            .withEndpoint("http://127.0.0.1:8443")
            .withSecret("secret")
            .build();
        System.out.println("Succesfully connected to FaunaDB as Admin\n");

        /*
         * Create a database
         */

        String DB_NAME = "demo";

        Value dbResults = adminClient.query(
            Do(
                If(
                    Exists(Database(DB_NAME)),
                    Delete(Database(DB_NAME)),
                    Value(true)
                ),
                CreateDatabase(Obj("name", Value(DB_NAME)))
            )
        ).get();

        System.out.println("Successfully created database: " + dbResults.at("name").to(String.class).get() + "\n" + dbResults + "\n");

        /*
         *  Create a client connection to the demo database
         */
        Value keyResults = adminClient.query(
            CreateKey(Obj("database", Database(Value(DB_NAME)), "role", Value("server")))
        ).get();

        String key = keyResults.at("secret").to(String.class).get();

        //Create the client query in a try-with-resources to ensure it gets closed
        //Because a Fauna Client implements AutoCloseable it will be closed when the try block finishes
        try (FaunaClient client = adminClient.newSessionClient(key)) {
            System.out.println("Connected to Fauna database " + DB_NAME + " with server role\n");
            runSpellExamples(DB_NAME, client);
        }

        /*
         * Delete the database and close the admin connection
         */
        deleteDB(adminClient, DB_NAME);
        adminClient.close();
        System.out.println("Disconnected from FaunaDB as Admin!");
    }

    private static void runSpellExamples(String DB_NAME, FaunaClient client) throws Exception {
        /*
         * Create the spell class and index
         */
        String SPELLS_CLASS = "spells";
        String INDEX_NAME = "spells_index";

        Value classResults = client.query(
            CreateCollection(
                Obj("name", Value(SPELLS_CLASS))
            )
        ).get();
        System.out.println("Create Class for " + DB_NAME + ":\n " + classResults + "\n");

        Value indexResults = client.query(
            CreateIndex(
                Obj("name", Value(INDEX_NAME), "source", Collection(Value(SPELLS_CLASS)))
            )
        ).get();
        System.out.println("Create Index for " + DB_NAME + ":\n " + indexResults + "\n");

        /*
         * Add some entries to the spells class
         */

        Value addFireResults = client.query(
            Create(
                Collection(Value(SPELLS_CLASS)),
                Obj("data",
                    Obj("name", Value("Fire Beak"), "element", Value("water"), "cost", Value(15))
                )
            )
        ).get();
        System.out.println("Added spell to class " + SPELLS_CLASS + ":\n " + addFireResults + "\n");


        Value addDragonResults = client.query(
            Create(
                Collection(Value(SPELLS_CLASS)),
                Obj("data",
                    Obj("name", Value("Water Dragon's Claw"), "element", Value("water"), "cost", Value(25))
                )
            )
        ).get();
        System.out.println("Added spell to class " + SPELLS_CLASS + ":\n " + addDragonResults + "\n");

        Value addHippoResults = client.query(
            Create(
                Collection(Value(SPELLS_CLASS)),
                Obj("data",
                    Obj("name", Value("Hippo's Wallow"), "element", Value("water"), "cost", Value(35))
                )
            )
        ).get();
        System.out.println("Added spell to class " + SPELLS_CLASS + ":\n " + addHippoResults + "\n");

        //The results at 'ref' are a resource pointer to the class that was just created.
        Value hippoRef = addHippoResults.at("ref");
        System.out.println("hippoRef = " + hippoRef);

        /*
         * Read the hippo back that we just created
         */

        Value readHippoResults = client.query(
            Select(Value("data"), Get(hippoRef))
        ).get();
        System.out.println("Hippo Spell:\n " + readHippoResults + "\n");

        //convert the hippo results into primitive elements
        String name = readHippoResults.at("name").to(String.class).get();
        Integer cost = readHippoResults.at("cost").to(Integer.class).get();
        String element = readHippoResults.at("element").to(String.class).get();

        System.out.println(String.format(
            "Spell Details: Name=%s, Cost=%d, Element=%s", name, cost, element));


        //This would return an empty option if the field is not found or the conversion fails
        Optional<String> optSpellElement = readHippoResults.at("element").to(String.class).getOptional();
        if (optSpellElement.isPresent()) {
            String element2 = optSpellElement.get();
            System.out.println("optional spell element = " + element2);
        } else {
            System.out.println("Something went wrong reading the spell");
        }

        /*
         * Query for all the spells in the index
         */
        Value queryIndexResults = client.query(
            SelectAll(Path("data", "id"),
                Paginate(
                    Match(Index(Value(INDEX_NAME)))
                ))
        ).get();

        Collection<String> spellsRefIds = queryIndexResults.asCollectionOf(String.class).get();
        System.out.println("spellsRefIds = " + spellsRefIds + "\n");

        /*
         * Store a Spell java class
         */
        Spell newSpell = new Spell("Water Dragon's Claw", "water", 25);
        Value storeSpellResult = client.query(
            Create(
                Collection(Value(SPELLS_CLASS)),
                Obj("data", Value(newSpell))
            )
        ).get();
        System.out.println("Stored spell:\n " + storeSpellResult + "\n");

        /*
         * Read the spell we just created
         */
        Value dragonRef = storeSpellResult.at("ref");
        Value getDragonResult = client.query(
            Select(Value("data"),
                Get(dragonRef)
            )
        ).get();
        Spell spell = getDragonResult.to(Spell.class).get();
        System.out.println("dragon spell: " + spell + "\n");

        /*
         * Store a list of Spells
         */

        Spell spellOne = new Spell("Chill Touch", "ice", 18);
        Spell spellTwo = new Spell("Dancing Lights", "fire", 45);
        Spell spellThree = new Spell("Fire Bolt", "fire", 32);
        List<Spell> spellList = Arrays.asList(spellOne, spellTwo, spellThree);

        //Lambda Variable for each spell
        String NXT_SPELL = "NXT_SPELL";

        //Encode the list of spells into an expression
        Expr encodedSpellsList = Value(spellList);

        //This query can be approximately read as for each spell in the list of spells evaluate the lambda function.
        //That lambda function creates a temporary variable with each spell in the list and passes it to the create function.
        //The create function then stores that spell in the database
        Value spellsListSave = client.query(
            Foreach(
                encodedSpellsList,
                Lambda(Value(NXT_SPELL),
                    Create(
                        Collection(Value(SPELLS_CLASS)),
                        Obj("data", Var(NXT_SPELL))
                    )
                )
            )
        ).get();

        System.out.println("Created list of spells from java list: \n" + spellsListSave + "\n");
        Collection<Spell> spellCollection = spellsListSave.asCollectionOf(Spell.class).get();
        System.out.println("save " + spellCollection.size() + " spells:");
        spellCollection.forEach(nextSpell -> System.out.println("   " + nextSpell));

        System.out.println("\n");

        /*
         * Read all Spells for the Spells Index
         */

        //Lambda Variable for each spell ref
        String REF_SPELL_ID = "NXT_SPELL";

        //Select causes the return data to be stored in the data field that is expected when the data is covered to a collection
        //The Map is equivalent to a functional map which maps over the set of all values returned by the paginate.
        //Then for each value in the list it runs the lambda function which gets and returns the value.
        Value findAllSpells = client.query(
            SelectAll(Path("data", "data"),
                Map(
                    Paginate(
                        Match(Index(Value(INDEX_NAME)))
                    ),
                    Lambda(Value(REF_SPELL_ID), Get(Var(REF_SPELL_ID))))
            )
        ).get();

        Collection<Spell> allSpellsCollection = findAllSpells.asCollectionOf(Spell.class).get();
        System.out.println("read " + allSpellsCollection.size() + " spells:");
        allSpellsCollection.forEach(nextSpell -> System.out.println("   " + nextSpell));
    }

    private static void deleteDB(FaunaClient adminClient, String dbName) throws Exception {
        /*
         * Delete the Database created
         */
        Value result = adminClient.query(
            If(
                Exists(Database(dbName)),
                Delete(Database(dbName)),
                Value(true)
            )
        ).get();
        System.out.println("Deleted database: " + dbName + ":\n " + result + "\n");
    }
}