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Flask-SQLalchemy update a row's information
...:
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80), unique=True)
data = db.Column(db.PickleType())
def __init__(self, name, data):
self.name = name
self.data = data
def __repr__(self):
return '<User %r>' % self.username
...
Predicate in Java
... a given input. For example, a RegexPredicate might implement Predicate<String>, and return true for any string that matches its given regular expression.
This is essentially an OOP abstraction for a boolean test.
For example, you may have a helper method like this:
static boolean isEven(...
Build the full path filename in Python
...uild the file path from a directory name, base filename, and a file format string?
4 Answers
...
demystify Flask app.secret_key
... computer. The secret plus the data-to-sign are used to create a signature string, a hard-to-recreate value using a cryptographic hashing algorithm; only if you have the exact same secret and the original data can you recreate this value, letting Flask detect if anything has been altered without per...
Why do we need a pure virtual destructor in C++?
...meter(const N_Configuration::Parameter& aParam);
std::map<std::string, std::string> m_Parameters;
};
struct NumericsParams : IParams
{
NumericsParams(const ModelConfiguration& aNumericsConf);
virtual ~NumericsParams();
double dt() const;
double ti() const;
do...
In SQL Server, when should you use GO and when should you use semi-colon ;?
...terminator. In another DBMS I have seen the ability to set the termination string. For example, you might specify that statements end with two pipe characters ||. You could then issue CREATE PROCEDURE ... much SQL ending in ; ... || and the double pipe ends the CREATE PROCEDURE statement. So my ques...
Confused about stdin, stdout and stderr?
...h the console (e.g. Keyboard input).
Used in C with scanf
scanf(<formatstring>,<pointer to storage> ...);
stdout
Produces output to the console.
Used in C with printf
printf(<string>, <values to print> ...);
stderr
Produces 'error' output to the console.
Used in C wit...
error: passing xxx as 'this' argument of xxx discards qualifiers
...simple: make the functions const as:
int getId() const {
return id;
}
string getName() const {
return name;
}
This is necessary because now you can call getId() and getName() on const objects as:
void f(const StudentT & s)
{
cout << s.getId(); //now okay, but error with ...
Is it possible to set a number to NaN or infinity?
...
Cast from string using float():
>>> float('NaN')
nan
>>> float('Inf')
inf
>>> -float('Inf')
-inf
>>> float('Inf') == float('Inf')
True
>>> float('Inf') == 1
False
...
An async/await example that causes a deadlock
... context).
GetJsonAsync starts the REST request by calling HttpClient.GetStringAsync (still within the context).
GetStringAsync returns an uncompleted Task, indicating the REST request is not complete.
GetJsonAsync awaits the Task returned by GetStringAsync. The context is captured and will be...