//fuzzy query by parameters
public async Task <PagedListForTask <EmployeeTask> > GetTasksAsync(TaskDtoParameters parameters)
{
if (parameters == null)
{
throw new ArgumentNullException(nameof(parameters));
}
var queryExpression = _context.EmployeeTasks as IQueryable <EmployeeTask>;
//判断datetime类型为空就看它和最小值相等与否，最小值是0001-01-01
//if (string.IsNullOrWhiteSpace(parameters.SearchTerm) && parameters.Deadline == DateTime.MinValue)
// return await PagedListForTask<EmployeeTask>.CreateAsnyc(queryExpression, parameters.PageNumber, parameters.PageSize);
//这里不能转成IEnumerable因为后面不能转成异步list,而IQueryable相当于生成不马上执行的sql查询语句，可以转成异步list
//var queryExpression = _context.EmployeeTasks as IEnumerable<EmployeeTask>;
if (parameters.Deadline != DateTime.MinValue)
{
parameters.Deadline = DateTime.Parse(parameters.Deadline.ToString().Trim());
queryExpression = queryExpression.Where(x => x.Deadline == parameters.Deadline);
}
if (!string.IsNullOrWhiteSpace(parameters.SearchTerm))
{
parameters.SearchTerm = parameters.SearchTerm.Trim();
queryExpression = queryExpression.Where(x => x.TaskName.Contains(parameters.SearchTerm) || x.TaskDescription.Contains(parameters.SearchTerm));
}
//根据排序字符串获取对应的排序属性
var mappingDictionary = _propertyMappingServiceForTask.GetPropertyMapping <EmployeeTaskDto, EmployeeTask>();
queryExpression = queryExpression.ApplySortForTask(parameters.OrderBy, mappingDictionary);
return(await PagedListForTask <EmployeeTask> .CreateAsnyc(queryExpression, parameters.PageNumber, parameters.PageSize));
}
//这里用拼接uri，返回的header里能看到翻页前后的uri地址,属于GetTasksBySearch的响应
private string CreateTasksResponseUri(TaskDtoParameters parameters, ResourceUriType type)
{
//PreviousPage and NextPage
switch (type)
{
//前一页
case ResourceUriType.PreviousPage:
return(Url.Link(nameof(GetTasksBySearch), new
{
pageNumber = parameters.PageNumber - 1,
pageSize = parameters.PageSize,
searchTerm = parameters.SearchTerm,
deadline = parameters.Deadline,
orderBy = parameters.OrderBy
})); //Url.Link拼接翻页的uri, 这里一定要带上所有的查询过滤条件(TaskDtoParameters里的),否则生成的uri翻页后的数据就不对了
case ResourceUriType.NextPage:
return(Url.Link(nameof(GetTasksBySearch), new
{
pageNumber = parameters.PageNumber + 1,
pageSize = parameters.PageSize,
searchTerm = parameters.SearchTerm,
deadline = parameters.Deadline,
orderBy = parameters.OrderBy
})); //Url.Link拼接翻页的uri
default:
return(Url.Link(nameof(GetTasksBySearch), new
{
pageNumber = parameters.PageNumber,
pageSize = parameters.PageSize,
searchTerm = parameters.SearchTerm,
deadline = parameters.Deadline,
orderBy = parameters.OrderBy
})); //Url.Link拼接翻页的uri
}
}
public async Task <ActionResult <IEnumerable <EmployeeTaskDto> > > GetTasksBySearch([FromQuery] TaskDtoParameters parameters)
{
if (!_propertyMappingServiceForTask.ExistsMapping <EmployeeTaskDto, EmployeeTask>(parameters.OrderBy))
{
return(BadRequest());
}
if (parameters == null)
{
return(BadRequest());
}
var employeeTasks = await _employeeTaskRepository.GetTasksAsync(parameters);
//有前一页就创造前一页的uri,没有就为空
//因为CreateTasksResponseUri用了Url.Link把datetime加密了，所以这里要解密一下，但是一般情况下，uri的datetime是不直接显示的，这里为了显示前后页的正确uri
var previousLink = employeeTasks.HasPrevious ? HttpUtility.UrlDecode(CreateTasksResponseUri(parameters, ResourceUriType.PreviousPage)) : null;
var nextLink = employeeTasks.HasNext ? HttpUtility.UrlDecode(CreateTasksResponseUri(parameters, ResourceUriType.NextPage)) : null;
//创建一个页码匿名类,没有类名，只是为了使用里面的属性
var paginationMetadata = new
{
totalCount = employeeTasks.TotalCount,
pageSize = employeeTasks.PageSize,
currentPage = employeeTasks.CurrentPage,
totalPage = employeeTasks.TotalPages,
previousLink,
nextLink
};
//把匿名类的属性添加到header里，命名为X-Pagination
Response.Headers.Add("X-Pagination", JsonSerializer.Serialize(paginationMetadata, new JsonSerializerOptions {
//不安全的字符会被转义,这里改一下不让转义
Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping
}));
var taskDto = _mapper.Map <IEnumerable <EmployeeTaskDto> >(employeeTasks);
return(Ok(taskDto));
}
