iot/labs/CSharpObjectJsonSchema/Controllers/ControllerExtensions.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Dynamic;
using System.Linq;
using System.Reflection;

namespace CSharpObjectJsonSchema.Controllers
{
    public static class ControllerExtensions
    {
        public static object GetJsonSchema<T>(this ControllerBase controller)
        {
            if (controller is null)
            {
                throw new ArgumentNullException(nameof(controller));
            }
            var metadata = controller.HttpContext.RequestServices.GetRequiredService<IModelMetadataProvider>().GetMetadataForType(typeof(T));

            return CreateJson(controller, metadata as DefaultModelMetadata);
        }

        public static object GetJsonSchema(this ControllerBase controller, Type type)
        {
            if (controller is null)
            {
                throw new ArgumentNullException(nameof(controller));
            }
            var metadata = controller.HttpContext.RequestServices.GetRequiredService<IModelMetadataProvider>().GetMetadataForType(type);

            return CreateJson(controller, metadata as DefaultModelMetadata);
        }

        public static object CreateJson(this ControllerBase controller, DefaultModelMetadata metadata)
        {
            if (metadata is null)
            {
                return null;
            }
            try
            {
                dynamic json = new ExpandoObject();
                var dictionary = (IDictionary<string, object>)json;
                //type
                if (metadata.IsComplexType && metadata.IsCollectionType)
                {
                    json.type = "array";
                    json.items = controller.GetJsonSchema(metadata.ModelType.GenericTypeArguments[0]);
                }
                else if (metadata.IsEnum)
                {
                    json.type = "string";
                    dictionary["enum"] = metadata.IsNullableValueType ? Enum.GetNames(metadata.ModelType.GenericTypeArguments[0]) : Enum.GetNames(metadata.ModelType);
                }
                else
                {
                    var modelType = metadata.IsNullableValueType ? metadata.ModelType.GenericTypeArguments[0] : metadata.ModelType;
                    if (modelType == typeof(string))
                    {
                        json.type = "string";
                    }
                    else if (modelType == typeof(int) || modelType == typeof(long))
                    {
                        json.type = "integer";
                    }
                    else if (modelType == typeof(float) || modelType == typeof(double) || modelType == typeof(decimal))
                    {
                        json.type = "number";
                    }
                    else if (modelType == typeof(bool))
                    {
                        json.type = "boolean";
                    }
                    else if (modelType == typeof(DateTime))
                    {
                        json.type = "string";
                    }
                    else
                    {
                        json.type = "object";
                    }
                }
                //title
                if (metadata.DisplayName != null)
                {
                    json.title = metadata.DisplayName;
                }
                foreach (var attribute in metadata.Attributes.Attributes)
                {
                    if (attribute is DescriptionAttribute descriptionAttribute)
                    {//description
                        json.description = descriptionAttribute.Description;
                    }
                    else if (attribute is RegularExpressionAttribute regularExpressionAttribute)
                    {//pattern
                        json.pattern = regularExpressionAttribute.Pattern;
                    }
                    else if (attribute is DataTypeAttribute dataTypeAttribute)
                    {//format
                        if (dataTypeAttribute.DataType == DataType.DateTime)
                        {
                            json.format = "date-time";
                        }
                        else if (dataTypeAttribute.DataType == DataType.Time)
                        {
                            json.format = "time";
                        }
                        else if (dataTypeAttribute.DataType == DataType.EmailAddress)
                        {
                            json.format = "email";
                        }
                        else if (dataTypeAttribute.DataType == DataType.Url)
                        {
                            json.format = "uri";
                        }
                        else if (dataTypeAttribute.DataType == DataType.Custom)
                        {//自定义
                            json.format = dataTypeAttribute.GetDataTypeName().ToLower();
                        }
                        else
                        {
                            json.format = dataTypeAttribute.DataType.ToString().ToLower();
                        }
                    }
                    else if (attribute is ReadOnlyAttribute readOnlyAttribute)
                    {//readOnly
                        json.readOnly = readOnlyAttribute.IsReadOnly;
                    }
                    else if (attribute is MinLengthAttribute minLengthAttribute)
                    {//minLength
                        json.minLength = minLengthAttribute.Length;
                    }
                    else if (attribute is MaxLengthAttribute maxLengthAttribute)
                    {//maxLength
                        json.maxLength = maxLengthAttribute.Length;
                    }
                    else if (attribute is StringLengthAttribute stringLengthAttribute)
                    {//minLength,maxLength
                        json.minLength = stringLengthAttribute.MinimumLength;
                        json.maxLength = stringLengthAttribute.MaximumLength;
                    }
                    else if (attribute is RangeAttribute rangeAttribute)
                    {//minimum,maximum
                        json.minimum = rangeAttribute.Minimum;
                        json.maximum = rangeAttribute.Maximum;
                    }
                    else if (attribute is ScaffoldColumnAttribute scaffoldColumnAttribute)
                    {//scaffold 自定义
                        json.scaffold = scaffoldColumnAttribute.Scaffold;
                    }
                    else if (attribute is HiddenInputAttribute hiddenInputAttribute)
                    {//hidden 自定义
                        json.hidden = hiddenInputAttribute.DisplayValue;
                    }
                    else if (attribute is UIHintAttribute uIHintAttribute)
                    {//ui 自定义
                        json.ui = uIHintAttribute.UIHint;
                    }
                    else if (attribute is CompareAttribute compareAttribute)
                    {//compare 自定义
                        json.compare = compareAttribute.OtherProperty;
                    }
                    else if (attribute is RemoteAttribute remoteAttribute)
                    {//remote 自定义
                        var routeData = attribute.GetType().GetProperty("RouteData", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(remoteAttribute) as RouteValueDictionary;
                        json.remote = new
                        {
                            url = controller.Url.Action(routeData["action"].ToString(), routeData["controller"].ToString(), new { Area = routeData["area"].ToString() }),
                            remoteAttribute.AdditionalFields,
                            //remoteAttribute.
                        };
                    }
                }
                dynamic properties = new ExpandoObject();
                var propertiesDictionary = (IDictionary<string, object>)properties;
                var requiredList = new List<string>();
                if (metadata.IsComplexType && !metadata.IsCollectionType && metadata.Properties.Any())
                {
                    foreach (var item in metadata.Properties)
                    {
                        var modelMetadataItem = item as DefaultModelMetadata;
                        propertiesDictionary[item.PropertyName] = CreateJson(controller, modelMetadataItem);
                        if (modelMetadataItem.IsRequired)
                        {
                            requiredList.Add(item.PropertyName);
                        }
                    }
                    json.properties = properties;
                    if (requiredList.Any())
                    {
                        json.required = requiredList;
                    }
                }
                return json;
            }
            catch (Exception ex)
            {
                return null;
            }
        }
    }
}