Azure function - CosmosDB

Make sure you are setting correct Data in File content according to your Azure CosmosDB schema and using a valid Connection String for your AzureWebJobsStorage and CosmosConnStr as per the comment by Matias Quaranta.

I have created my CosmosDB Database and Container by referring this MS Document.

My Function code:-

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;

public class FileContents
{
    [JsonProperty("id")]
    public string Id { get; set; }

    [JsonProperty("category")]
    public string Category { get; set; }

    [JsonProperty("name")]
    public string Name { get; set; }

    [JsonProperty("description")]
    public string Description { get; set; }

    [JsonProperty("isComplete")]
    public bool IsComplete { get; set; }
}

public static class MyFunctions
{
    [FunctionName("BindingTrigger")]
    public static async Task<IActionResult> BindingTrigger(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
        ILogger log,
        [Blob("sample-blob/test.txt", FileAccess.Read, Connection = "AzureWebJobsStorage")] Stream outputBlob,
        [CosmosDB(
            databaseName: "ToDoList",
            containerName: "Items", // Replace with your container name
            Connection = "CosmosConnStr",
            CreateIfNotExists = true)] IAsyncCollector<FileContents> documents)
    {
        log.LogInformation("C# HTTP trigger function processed a request.");

        try
        {
            if (outputBlob != null)
            {
                outputBlob.Position = 0; // Reset stream position

                // Deserialize the JSON document structure based on your Cosmos DB schema
                // Modify this according to the actual data you want to insert
                var fileContent = new FileContents
                {
                    Id = "1",
                    Category = "personal",
                    Name = "groceries",
                    Description = "Pick up apples and strawberries.",
                    IsComplete = false
                };

                await documents.AddAsync(fileContent);

                return new OkObjectResult("Data inserted into Cosmos DB");
            }
            else
            {
                log.LogError("Blob is null or inaccessible.");
                return new BadRequestObjectResult("Blob is null or inaccessible.");
            }
        }
        catch (Exception ex)
        {
            log.LogError(ex, "Error processing the request");
            return new StatusCodeResult(StatusCodes.Status500InternalServerError);
        }
    }
}

My local.settings.json:-

{
    "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "DefaultEndpointsProtocol=https;AccountName=siliconstrg89;AccountKey=xxxxxxxxxx+AStEQBMoA==;EndpointSuffix=core.windows.net",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "CosmosConnStr": "AccountEndpoint=https://silicon-cosmos.documents.azure.com:443/;AccountKey=xxxxxxxxxxAoACDb4rmfgA==;"
  }
}

Output:-

Your code according to your schema should look like below:-

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Extensions.Logging;
using System;
using System.IO;
using System.Threading.Tasks;

public class FileContents
{
    public string PartitionKey { get; set; }
    public string RowKey { get; set; }
    public string Name { get; set; }
    public string Contents { get; set; }
}

public static class MyFunctions
{
    [FunctionName("BindingTrigger")]
    public static async Task<IActionResult> BindingTrigger(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
        ILogger log,
        [Blob("sample-blob/test.txt", FileAccess.Read, Connection = "AzureWebJobsStorage")] Stream outputBlob,
        [CosmosDB("azurefunctions", "FileContents", Connection = "CosmosConnStr", CreateIfNotExists = true)] IAsyncCollector<FileContents> documents)
    {
        log.LogInformation("C# HTTP trigger function processed a request.");

        try
        {
            if (outputBlob != null)
            {
                outputBlob.Position = 0; // Reset stream position
                await documents.AddAsync(new FileContents
                {
                    PartitionKey = Guid.NewGuid().ToString(),
                    RowKey = "1",
                    Name = "test.txt",
                    Contents = outputBlob.Length.ToString()
                });

                return new OkObjectResult($"Size of file: {outputBlob.Length}");
            }
            else
            {
                log.LogError("Blob is null or inaccessible.");
                return new BadRequestObjectResult("Blob is null or inaccessible.");
            }
        }
        catch (Exception ex)
        {
            log.LogError(ex, "Error processing the request");
            return new StatusCodeResult(StatusCodes.Status500InternalServerError);
        }
    }
}