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Understanding :source option of has_one/has_many through of Rails
...'ve chosen to namespace the Dog::Breed, because we want to access Dog.find(123).breeds as a nice and convenient association.
Now, if we now want to create a has_many :dog_breeds, :through => :dogs association on Pet, we suddenly have a problem. Rails won't be able to find a :dog_breeds associati...
How do I create a unique constraint that also allows nulls?
...et_AllowNull
UNIQUE (TicketID, TicketUnique);
If IssueID 1 has ticket 123, the UNIQUE constraint will be on values (123, NULL). If IssueID 2 has no ticket, it will be on (NULL, 2). Some thought will show that this constraint cannot be duplicated for any row in the table, and still allows multip...
Get users by name property using Firebase
...:
Write to Firebase with a unique, known key:
ref.child('users').child('123').set({ "first_name": "rob", "age": 28 })
Append to lists with an auto-generated key that will automatically sort by time written:
ref.child('users').push({ "first_name": "rob", "age": 28 })
Listen for changes in data ...
Is JavaScript an untyped language?
...licit compiler interjection, the instruction will error during run-time.
"12345" * 1 === 12345 // string * number => number
Strongly typed means there is a compiler, and it wants you an explicit cast from string to integer.
(int) "12345" * 1 === 12345
In either case, some compiler's featur...
How to convert std::string to lower case?
...aracters allowed in the french language. For instance a string 'Test String123. É Ï\n' will be converted to : 'test string123. É Ï\n' although characters É Ï and their lower case couterparts 'é' and 'ï', are allowed in french. It seems that no solution for that was provided by other message...
Fastest way to check if a string is JSON in PHP?
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$phone = '021234567'; var_dump(isJson($phone)); return true no! it should return false.
– vee
Jan 2 '14 at 17:12
...
Cast a Double Variable to Decimal
...hould use the M when declaring a new literal decimal value:
decimal dec = 123.45M;
(Without the M, 123.45 is treated as a double and will not compile.)
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Does Javascript pass by reference? [duplicate]
...cript!
Call-by-Value
Primitive types are passed by-value:
var num = 123, str = "foo";
function f(num, str) {
num += 1;
str += "bar";
console.log("inside of f:", num, str);
}
f(num, str);
console.log("outside of f:", num, str);
Reassignments inside a function scope are ...
Difference between filter and filter_by in SQLAlchemy
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Be careful when using .filter. a query like id=12345, query(users).filter(id == id) will not filter on users.id. Instead, it will evaluate id == id as True and return all users. You need to use .filter(users.id == id) (as demoed above). I made this mistake earlier today.
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What is a method group in C#?
...) overload which takes a string parameter:
Func<string,string> fn = 123.ToString;
Console.WriteLine(fn("00000000"));
This example picks the ToString() overload which takes no parameters:
Func<string> fn = 123.ToString;
Console.WriteLine(fn());
...