default-value

问题 I'm new to JavaScript and I need some help with a simple problem I'm having: I have one empty input field, and two links ( anchors ) with differing values for the title attribute. I'd like to write a small piece of JavaScript that changes the value of the input element to the title of whichever link the user clicks. For example: First link = Prague Second link = Budapest When I click "Budapest" I'd like the value of the input element to change to "Budapest" If needed I can supply a basic

问题 in variable-length parameters function, the '...' must be place last. And default value enabled parameters must be last, too. so, how about both needed in the same one function? Now I have a log utility: void MyPrint(int32_t logLevel, const char *format, ...), which used to print log according to 'logLevel'. However, sometimes I hope it can be used as: MyPrint("Log test number%d", number), without 'logLevel' needed. The question: Default arguments and variadic functions didn't help. 回答1: In

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Does Java support default parameter values? Suppose I want to make default parameter value in C++, then we can express it as below. void functionName(char *param1, int param2=2); But if I want to make this in Java, then is it possible. Currently I am doing as below public functionName(String param1) { this(param1, 2); } public functionName(String param1, int param2) { .......... } 回答1: It is not possible in Java

问题 I have a model which contains FileField as below class Employer(models.Model): logo = models.FileField(storage=FileSystemStorage(location=settings.MEDIA_ROOT), upload_to='logos') The question is how can I add a default file like "{{ MEDIA_ROOT}}/logos/anonymous.jpg" to this filefield ? 回答1: You can specify the default file to use for that field as follows: class Employer(models.Model): logo = models.FileField(storage=FileSystemStorage(location=settings.MEDIA_ROOT), upload_to='logos', default=

问题 I have a model which contains FileField as below class Employer(models.Model): logo = models.FileField(storage=FileSystemStorage(location=settings.MEDIA_ROOT), upload_to='logos') The question is how can I add a default file like "{{ MEDIA_ROOT}}/logos/anonymous.jpg" to this filefield ? 回答1: You can specify the default file to use for that field as follows: class Employer(models.Model): logo = models.FileField(storage=FileSystemStorage(location=settings.MEDIA_ROOT), upload_to='logos', default=

问题 I deleted my db.sqlite3 and the file on my migration folder except __init__.py but including the __pycache__ folder. My app's models are multiple files in a folder with an __init__.py file with some import and an __all__ variable (I don't know if this matter). From the prompt I give the first migrate command and it look to work (migrating sessions, admin, auth, registration, contenttypes. There isn't my app 'core'). So i give the first makemigrations command and again the migrate command.

问题 I am working on a late-2019 Macbook Pro, which supports the P3 color gamut (wide color). I'm building a website that includes large blocks of vivid color, where I just want the colors to be as bright as possible. Most of the intended audience will also have P3-capable monitors. I discovered that my website looks amazing in Firefox -- much better than it does in Safari. It turns out that Firefox doesn't do any color management so the full P3 gamut is applied. Safari converts (or preserves) my

问题 I am working on a late-2019 Macbook Pro, which supports the P3 color gamut (wide color). I'm building a website that includes large blocks of vivid color, where I just want the colors to be as bright as possible. Most of the intended audience will also have P3-capable monitors. I discovered that my website looks amazing in Firefox -- much better than it does in Safari. It turns out that Firefox doesn't do any color management so the full P3 gamut is applied. Safari converts (or preserves) my

问题 I am working on a late-2019 Macbook Pro, which supports the P3 color gamut (wide color). I'm building a website that includes large blocks of vivid color, where I just want the colors to be as bright as possible. Most of the intended audience will also have P3-capable monitors. I discovered that my website looks amazing in Firefox -- much better than it does in Safari. It turns out that Firefox doesn't do any color management so the full P3 gamut is applied. Safari converts (or preserves) my

问题 This question already has answers here : MySQL default value as other field's value (2 answers) Closed 2 years ago . I have table of users in my MySQL database. Is it possible to set default value of column profile_url to value of column Id ? 回答1: You could use trigger to implement the feature. For example: CREATE TRIGGER defaultUrl BEFORE INSERT ON MyTable FOR EACH ROW SET NEW.profile_url = IFNULL(NEW.profile_url, NEW.id); The expression creates a trigger named defaultUrl that activates