WriteOneDoc.java

package com.danielrocks.function.cosmos.output;

import java.util.Optional;
import java.util.Random;

import com.microsoft.azure.functions.ExecutionContext;
import com.microsoft.azure.functions.HttpMethod;
import com.microsoft.azure.functions.HttpRequestMessage;
import com.microsoft.azure.functions.annotation.AuthorizationLevel;
import com.microsoft.azure.functions.annotation.CosmosDBOutput;
import com.microsoft.azure.functions.annotation.FunctionName;
import com.microsoft.azure.functions.annotation.HttpTrigger;

/**
 * Azure Functions with HTTP Trigger.
 * 
 * The following example shows a Java function that uses the CosmosDBOutput annotation
 * to return a single JSON document that will be written to a CosmosDB collection.
 * 
 * The function is triggered by an HTTP request that uses query string data to set the 'description'
 * field of the saved document.
 */
public class WriteOneDoc {
    /**
     * This function listens at endpoint "/api/WriteOneDoc". Two ways to invoke it using "curl" command in bash:
     * 1. curl -d "HTTP Body" {your host}/api/WriteOneDoc&desc={description}
     * 2. curl "{your host}/api/WriteOneDoc?desc={description}"
     */
    @FunctionName("WriteOneDoc")
    @CosmosDBOutput(name = "database", 
      databaseName = "ToDoList",
      collectionName = "Items", 
      connectionStringSetting = "Cosmos_DB_Connection_String")
    public String run(
            @HttpTrigger(name = "req", 
              methods = {HttpMethod.GET, HttpMethod.POST}, 
              authLevel = AuthorizationLevel.ANONYMOUS) 
            HttpRequestMessage<Optional<String>> request,
            final ExecutionContext context) {

        // Item list
        context.getLogger().info("Parameters are: " + request.getQueryParameters());

        // Parse query parameter        
        String query = request.getQueryParameters().get("desc");
        String name = request.getBody().orElse(query);

        // Generate random ID
        final int id = Math.abs(new Random().nextInt());

        // Generate document
        final String jsonDocument = "{\"id\":\"" + id + "\", " + 
                                    "\"description\": \"" + name + "\"}";

        context.getLogger().info("Document to be saved: " + jsonDocument);

        return jsonDocument;
    }
}