select

问题 I would like to create a function to retrieve a List of a given property name's Type. But i dont know yet how to create a working lambda selector. public IList<object> GetDistinctListOfProperty(string propertyName) { var propInfoByName = typeof(T).GetProperty(propertyName); if (propInfoByName == null) return new List<object>(); using (var db = new ApplicationDbContext()) { var lambda = //TODO return db.Set<T>().Select(lambda).Distinct().ToList(); } } 回答1: You can use this method to generate

问题 I am building a JSON API in Ruby on Rails. I want to have write-only user accounts that are supposed to feed data to the system but who should not be allowed to read from it. In order to achieve an extra layer of security, I'd like to enforce this rule at the database level. The idea is to have a "writer" type of user which uses a separate connection to the database. This connection should be allowed to insert / update / delete but not to select. I have everything set up nicely but

问题 I am building a JSON API in Ruby on Rails. I want to have write-only user accounts that are supposed to feed data to the system but who should not be allowed to read from it. In order to achieve an extra layer of security, I'd like to enforce this rule at the database level. The idea is to have a "writer" type of user which uses a separate connection to the database. This connection should be allowed to insert / update / delete but not to select. I have everything set up nicely but

问题 I am building a JSON API in Ruby on Rails. I want to have write-only user accounts that are supposed to feed data to the system but who should not be allowed to read from it. In order to achieve an extra layer of security, I'd like to enforce this rule at the database level. The idea is to have a "writer" type of user which uses a separate connection to the database. This connection should be allowed to insert / update / delete but not to select. I have everything set up nicely but

问题 I am building a JSON API in Ruby on Rails. I want to have write-only user accounts that are supposed to feed data to the system but who should not be allowed to read from it. In order to achieve an extra layer of security, I'd like to enforce this rule at the database level. The idea is to have a "writer" type of user which uses a separate connection to the database. This connection should be allowed to insert / update / delete but not to select. I have everything set up nicely but

问题 I am not able to understand how Cartesian product works. Consider the simple schema: mysql> select * from account; +----------------+-------------+---------+ | account_number | branch_name | balance | +----------------+-------------+---------+ | A101 | Downtown | 500 | | A102 | Perryridge | 400 | | A201 | Brighton | 900 | | A215 | Mianus | 700 | | A217 | Brighton | 750 | | A222 | Redwood | 700 | | A305 | Round Hill | 350 | +----------------+-------------+---------+ 7 rows in set (0.00 sec)

问题 Hi I am trying to implement material UI autocomplete dropbox with an icon next to the displayed text. my implementation is working, but when I select one of the options its not being displayed. The problem is with this part of the code: renderInput={params => ( <Fragment> <TextField {...params} variant="outlined" label="Select Account" placeholder="Favorites" margin="normal" fullWidth /> </Fragment> )} if I remove he icon rendering from getOptionLabel then when selecting the selected text

问题 On my page there are 2 dropdowns, one is a regular select for "Cities" and the other one is a multiselect using bootstrap for "Neighborhoods" of each City. The selected option on the first dropdown will set the options on the second dropdown. I already have it working with regular selects, but with multiselect using bootstrap, I am unable to get the options to change based on the selection. My original question and code This is the code I am trying now -- var select_clone = $('<select>')

问题 my select option group is like <select multiple class="form-control form-white" data-placeholder="Select Courses"> <option value="all">All</option> <optgroup label="Play School"> <option value="1">All</option> <option value="2">Sec A</option> <option value="3">Sec B</option> </optgroup> <optgroup label="Nursery"> <option value="1">All</option> <option value="2">Sec A</option> <option value="3">Sec C</option> </optgroup> <optgroup label="LKG"> <option value="1">All</option> <option value="2"

问题 How can I determine the value of the selected dropdown options using javascript. I can't use id selector so I was trying with document.getElementsByClassName. I understand that returns a set of values. Here is a simplified code I am trying to use: <div id="MDL" class="dates"> <p>Select Dates and Price</p> <select class="datevalue"> <option value="30">17th July - £30</option> <option value="45">17th July - £45</option> <option value="70">17th July - £70</option> <option value="30">18th July -