default-value | 易学教程

Inserting NULL into NOT NULL columns with Default Value

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问题 For a bit of background, we use Zend Framework 2 and Doctrine at work. Doctrine will always insert NULL for values we do not populate ourselves. Usually this is okay as if the field has a default value, then it SHOULD populate the field with this default value. For one of our servers running MySQL 5.6.16 a query such as the one below runs and executes fine. Although NULL is being inserted into a field which is not nullable, MySQL populates the field with its default value on insert. On

Define default values for Laravel form fields

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问题 To pre-populate form field, we can add 'value' to form field in create.blade.php: {{ Form::text('title', 'Some default title') }} Is there a way to do that task elsewhere (maybe in model or controller?). I'd like to have code for form fields identical in create & edit view. Thanks! 回答1: Okay, so here we are... I used Laravel's form model binding in the example. (I work with User model/db table). If this topic is not clear for you, take a look at this http://laravel.com/docs/html#form-model

PHP assignment with a default value

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问题 What's a nicer way to do the following, that doesn't call f() twice? $x = f() ? f() : 'default'; 回答1: In PHP 5.3, you can also do: $a = f() ?: 'default'; See the manual on ?: operator. 回答2: This seems to work fine: $x = f() or $x = 'default'; 回答3: function f() { // conditions return $if_something ? $if_something : 'default'; } $x = f(); 回答4: $x = ($result = foo()) ? $result : 'default'; test 回答5: You could save it to a variable. Testcase: function test() { echo 'here'; return 1; } $t = test()

How can I parse String to int with the default value? [duplicate]

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This question already has an answer here: Good way to encapsulate Integer.parseInt() 23 answers I need to parse a string user id into integer for that I used Integer.parseInt(String s) but it returns null/nil, if there string has/holds non-decimal/integer value and in that case, I need to assign default integer value as 0 . I tried this but it (? 0) seems not working and I don't know whether it is correct syntax or not. String userid = "user001"; int int_userid = Integer.parseInt(userid) ? 0; How can assign default value to integer if there is null assignment? String userid is a parameter

C++ variadic template function parameter with default value

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问题 I have a function which takes one parameter with a default value. Now I also want it to take a variable number of parameters and forward them to some other function. Function parameters with default value have to be last, so... can I put that parameter after the variadic pack and the compiler will detect whether I'm supplying it or not when calling the function? (Assuming the pack doesn't contain the type of that one last parameter. If necessary, we can assume that, because that type is

OptionalAttribute parameter's default value?

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问题 MSDN's VS2010 Named and Optional Arguments (C# Programming Guide) tells us about optional parameters in C#, showing code like I'd expect: public void ExampleMethod(int required, string optionalstr = "default string", int optionalint = 10) Ok, but it also says: You can also declare optional parameters by using the .NET OptionalAttribute class. OptionalAttribute parameters do not require a default value. I read MSDN's OptionalAttribute page, and done searches online (which shows lots of people

django-admin formfield_for_* change default value per/depending on instance

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问题 I'm trying to change the default value of a foreignkey-formfield to set a Value of an other model depending on the logged in user . But I'm racking my brain on it... This: Changing ForeignKey’s defaults in admin site would an option to change the empty_label, but I need the default_value. #Now I tried the following without errors but it didn't had the desired effect: class EmployeeAdmin(admin.ModelAdmin): ... def formfield_for_foreignkey(self, db_field, request=None, **kwargs): formfields=

es6 how to use default parameters that go before non-default parameters?

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I am a bit rusty on default parameters, and I am wondering how can I use a default value for a parameter if it goes before parameters without defaults? In the example from Redux.js below, when will the default value {} for the state parameter be useful? (since you can't default the next parameter)? const todo = (state = {}, action) => { switch (action.type) { //... case 'TOGGLE_TODO': if (state.id !== action.id) { return state } return Object.assign({}, state, { completed: !state.completed }) default: return state } } The usage in question is specific to redux.js . The default value for the

ruby default argument idiom

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What's the idiom in Ruby when you want to have a default argument to a function, but one that is dependent on another parameter / another variable? For example, in Python, an example is: def insort_right(a, x, lo=0, hi=None): if hi is None: hi = len(a) while lo < hi: mid = (lo+hi)//2 if x < a[mid]: hi = mid else: lo = mid+1 a.insert(lo, x) Here, if hi is not supplied, it should be len(a) . You can't do len(a) in the default argument list, so you assign it a sentinel value, None, and check for that. What would the equivalent be in Ruby? def foo(a, l = a.size) end 来源： https://stackoverflow.com

insert DEFAULT values

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Is there ANY difference between those two statements?: INSERT INTO distributors (did, dname) VALUES (DEFAULT, 'XYZ Widgets'); and: INSERT INTO distributors (dname) VALUES ('XYZ Widgets'); I mean is there at least one reason to use one or another pattern in some particular situation or is it completely the same? did is a serial column. It's exactly the same thing. No need to pick one instead of the other. Usually default keyword is handy when you have computer-generated code. It makes life easier to just use every single column in the insert clause and just use default when you don't have a