大约有 18,336 项符合查询结果（耗时：0.0250秒） [XML]
What does inverse_of do? What SQL does it generate?
...the documentation, it seems like the :inverse_of option is a method for avoiding SQL queries, not generating them. It's a hint to ActiveRecord to use already loaded data instead of fetching it again through a relationship.
Their example:
class Dungeon < ActiveRecord::Base
has_many :traps, :in...
The relationship could not be changed because one or more of the foreign-key properties is non-nulla
I am getting this error when I GetById() on an entity and then set the collection of child entities to my new list which comes from the MVC view.
...
Select2 dropdown but allow new values by user?
...page) {
return {results: data.results};
},
"url": url
},
id: function(object) {
return object.text;
},
//Allow manually entered text in drop down.
createSearchChoice:function(term, data) {
if ( $(data).filter( function() {
return this.text.localeCompare(term)===...
How do I iterate over a JSON structure? [duplicate]
... four:4, five:5 };
jQuery.each(arr, function() {
$("#" + this).text("My id is " + this + ".");
return (this != "four"); // will stop running to skip "five"
});
jQuery.each(obj, function(i, val) {
$("#" + i).append(document.createTextNode(" - " + val));
});
...
jQuery get selected option value (not the text, but the attribute 'value')
...he option.
$('select[name=selector] option').filter(':selected').val()
Side note: Using filter is better then using :selected selector directly in the first query.
If inside a change handler, you could use simply this.value to get the selected option value. See demo for more options.
//ways...
T-SQL: Deleting all duplicate rows but keeping one [duplicate]
...
You didn't say what version you were using, but in SQL 2005 and above, you can use a common table expression with the OVER Clause. It goes a little something like this:
WITH cte AS (
SELECT[foo], [bar],
row_number() OVER...
SQL Add foreign key to existing column
...
Error indicates that there is no UserID column in your Employees table. Try adding the column first and then re-run the statement.
ALTER TABLE Employees
ADD CONSTRAINT FK_ActiveDirectories_UserID FOREIGN KEY (UserID)
REFERENCES ActiveDirectories(id);
...
How to enter in a Docker container already running with a new TTY
...le to access the container from another shell in order to "poke around" inside it and examine the files. At the moment, if I attach to the container, I am left looking at the Apache daemon and cannot run any commands.
...
How to persist a property of type List in JPA?
... String> {
private static final String SPLIT_CHAR = ";";
@Override
public String convertToDatabaseColumn(List<String> stringList) {
return String.join(SPLIT_CHAR, stringList);
}
@Override
public List<String> convertToEntityAttribute(String string) {
...
How to determine if a record is just created or updated in after_save
...king to use this for an after_save callback.
A simpler solution is to use id_changed? (since it won't change on update) or even created_at_changed? if timestamp columns are present.
Update: As @mitsy points out, if this check is needed outside of callbacks then use id_previously_changed?. See docs...