c# - 如何通过输入和输出绑定(bind)连接 Azure Functions 2.0 CosmosDB？

Question

我无法弄清楚如何在 Azure Function 2.0 中同时使用 in 和 out 绑定(bind)访问 CosmosDB。

我可以从一个 HttpTrigger 函数从我的 cosmosDB 集合和另一个 HttpTrigger 函数中获取一个 json 对象，将 json 对象写入集合

我想不通的是如何首先从 cosmosDB 集合中读取 json 对象，对其进行一些更改，然后从同一个函数中再次将其写回。

下面的代码应该概述我的问题

[FunctionName("WebrootConnector")]
        public static void Run(
            [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
            [CosmosDB(
                databaseName: "customersDB",
                collectionName: "customers",
                ConnectionStringSetting = "CosmosDBConnection", 
                CreateIfNotExists = true,
                Id = "999",
                PartitionKey = "/id")] 
                Customers customersObject, // in binding
                out dynamic customersDocumentToDB, // out binding
                ILogger log)
        {
            // Chect if a customersObject is recieved from cosmosDB
            if (customersObject == null)
            {
                // Create a new Customers object
                customersObject = new Customers();
                // Set the id of the database document (should always be the same)
                customersObject.Id = 999;
                // Create a new empty customer list on the customers object
                customersObject.customers = new List<Customer>();

                // Add some customers to the list

            } 
            else
            {
                // if a object is received from the database
                // do something with it.
            }

            if (customersObject.customers != null)
            {
                // Write the object back to the cosmosDB collection
                customersDocumentToDB = customersObject;
                log.LogInformation($"Data written to customerDB");
            }
            else
            {
                customersDocumentToDB = null;
                log.LogInformation($"Nothing to write to database");
            }
         }

Answer 1

您必须使用 两个单独的绑定(bind) ，一个用于输入(您的查询)，一个用于输出。完整列表位于 official docs for the Bindings .

[FunctionName("WebrootConnector")]
public static void Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
    [CosmosDB(
        databaseName: "customersDB",
        collectionName: "customers",
        ConnectionStringSetting = "CosmosDBConnection", 
        CreateIfNotExists = true,
        Id = "999",
        PartitionKey = "/id")] 
        Customers customersObject, // in binding
     [CosmosDB(
        databaseName: "customersDB",
        collectionName: "customers",
        ConnectionStringSetting = "CosmosDBConnection"] 
        out dynamic customersDocumentToDB, // out binding
        ILogger log)

如果要存储多于 1 个文档，可以使用 IAsyncCollector :

[FunctionName("WebrootConnector")]
public static void Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
    [CosmosDB(
        databaseName: "customersDB",
        collectionName: "customers",
        ConnectionStringSetting = "CosmosDBConnection", 
        CreateIfNotExists = true,
        Id = "999",
        PartitionKey = "/id")] 
        Customers customersObject, // in binding
     [CosmosDB(
        databaseName: "customersDB",
        collectionName: "customers",
        ConnectionStringSetting = "CosmosDBConnection"] 
        IAsyncCollector<dynamic> customersDocumentToDB, // out binding
        ILogger log)

当您想保存文档时，请调用 await customersDocumentToDB.AddAsync(newDocument) .