sdk/FunctionMetadataLoaderExtension/FunctionMetadataJsonReader.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs.Script.Description;
using Microsoft.Extensions.Options;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace Microsoft.Azure.WebJobs.Extensions.FunctionMetadataLoader
{
    internal class FunctionMetadataJsonReader
    {
        private readonly IOptions<FunctionMetadataJsonReaderOptions> _options;
        private const string FileName = "functions.metadata";

        public FunctionMetadataJsonReader(IOptions<FunctionMetadataJsonReaderOptions> options)
        {
            _options = options ?? throw new ArgumentNullException(nameof(options));
        }

        public virtual async Task<ImmutableArray<FunctionMetadata>> ReadMetadataAsync()
        {
            string metadataFile = Path.Combine(_options.Value.FunctionMetadataFileDrectory, FileName);

            if (!File.Exists(metadataFile))
            {
                throw new FileNotFoundException($"Function metadata file not found. File path used:{metadataFile}");
            }

            using var fs = File.OpenText(metadataFile);
            using var js = new JsonTextReader(fs);
            JArray functionMetadataJson = (JArray)await JToken.ReadFromAsync(js);
            var functionList = new List<FunctionMetadata>();

            foreach (JToken function in functionMetadataJson)
            {
                FunctionMetadata metadata = function.ToObject<FunctionMetadata>()!;

                // We need to re-add these by going through the BindingMetadata factory
                metadata.Bindings.Clear();

                if (function["bindings"] is not JArray bindingArray || bindingArray.Count == 0)
                {
                    throw new FormatException("At least one binding must be declared.");
                }

                foreach (JObject binding in bindingArray.Cast<JObject>())
                {
                    metadata.Bindings.Add(BindingMetadata.Create(binding));
                }

                functionList.Add(metadata);
            }

            return functionList.ToImmutableArray();
        }
    }
}