OrchardCore 中为现有动态类型实现自定义Graphql 查询

很多情况下，需要自定义逻辑来实现 Graphql查询,

比如 通过Graphql 查询当前用户信息

因为 Graphql 是强类型的，所以我们要先实现一个Schema

定义一个类，实现 OrchardCore.Apis.GraphQL.ISchemaBuilder 接口

 public class UserInfoQueryFieldTypeProvider : ISchemaBuilder

构建自定义字段 

 public Task BuildAsync(ISchema schema)
        {
            //从已注册类型中查找指定类型字段
            var typetype = schema.Query.Fields.OfType<ContentItemsFieldType>()
                .FirstOrDefault(x => x.Name == "UserProfile");
            if (typetype == null)
            {
                return null;
            }
            //因为系统自动注册的类型是集合形式的，所以先要进行转换
            var type = (ListGraphType)typetype.ResolvedType;
            var field = new FieldType
            {
                Name = "Me",
                Description = S["Information about the current login user."],
                Type = typeof(ContentItemInterface),
                ResolvedType = type.ResolvedType,
                Resolver = new AsyncFieldResolver<ContentItem>(ResolveAsync)
            };

            schema.Query.AddField(field);

            return Task.CompletedTask;
        }

告知 系统何时更新Schema ,因为我们的 当前用户是 基于现有动态类型实现的，所以监听 类型定义的变更即可

        public Task<string> GetIdentifierAsync()
        {
            var contentDefinitionManager = _httpContextAccessor.HttpContext.RequestServices.GetService<IContentDefinitionManager>();
            return contentDefinitionManager.GetIdentifierAsync();
        }

 

自定义逻辑实现：

 private async Task<ContentItem> ResolveAsync(IResolveFieldContext context)
        {
            var serviceProvider = _httpContextAccessor.HttpContext.RequestServices;
            var userManager = serviceProvider.GetRequiredService<UserManager<IUser>>();
            var user = await userManager.FindByNameAsync(_httpContextAccessor.HttpContext.User.Identity.Name) as User;
            var contentManager = serviceProvider.GetService<IContentManager>();
            var contentItem = await contentManager.GetAsync(user.UserId);
            if (contentItem == null)
            {
                contentItem = await contentManager.NewAsync("UserProfile");
                contentItem.Owner = user.UserId;

                contentItem.Alter<UserProfile>(profile =>
                {
                    profile.Roles.Values = user.RoleNames.ToArray();
                    profile.UserName.Text = user.UserName;
                    profile.Email.Text = user.Email;
                });
            }

            return contentItem;
        }

 

 最后别忘了向DI注册

services.AddSingleton<ISchemaBuilder, UserInfoQueryFieldTypeProvider>();

 

以上示例实现了一个 非集合类型的查询

如果 需要返回集合类型 参考如下代码： 

        public Task BuildAsync(ISchema schema)
        {
            var typetype = schema.Query.Fields.OfType<ContentItemsFieldType>()
                .FirstOrDefault(x => x.Name == nameof(AntdMenuItem));
            if (typetype == null)
            {
                return Task.CompletedTask;
            }

            var field = new FieldType
            {
                Name = "userMenus",
                Description = S["获取用户菜单"],
                Type = typeof(ListGraphType<ContentItemType>),
                ResolvedType = typetype.ResolvedType,
                Resolver = new LockedAsyncFieldResolver<IEnumerable<ContentItem>>(ResolveAsync)
            };

            schema.Query.AddField(field);

            return Task.CompletedTask;
        }