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Determine what attributes were changed in Rails after_save callback?

I'm setting up an after_save callback in my model observer to send a notification only if the model's published attribute was changed from false to true. Since methods such as changed? are only useful before the model is saved, the way I'm currently (and unsuccessfully) trying to do so is as fol...
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Is there a null-coalescing (Elvis) operator or safe navigation operator in javascript?

...swered Jun 17 '16 at 15:20 James_picJames_pic 2,9321414 silver badges2323 bronze badges ...
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Get difference between 2 dates in JavaScript? [duplicate]

... between those two UTC dates. Now, the solution can be written as, const _MS_PER_DAY = 1000 * 60 * 60 * 24; // a and b are javascript Date objects function dateDiffInDays(a, b) { // Discard the time and time-zone information. const utc1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate()); ...
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How to change collation of database, table, column?

The database is latin1_general_ci now and I want to change collation to utf8mb4_general_ci . 19 Answers ...
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Determine Whether Two Date Ranges Overlap

... Proof: Let ConditionA Mean that DateRange A Completely After DateRange B _ |---- DateRange A ------| |---Date Range B -----| _ (True if StartA > EndB) Let ConditionB Mean that DateRange A is Completely Before DateRange B |---- DateRange A ...
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In MySQL, can I copy one row to insert into the same table?

...rd Challis's technique with a few changes: CREATE TEMPORARY TABLE tmptable_1 SELECT * FROM table WHERE primarykey = 1; UPDATE tmptable_1 SET primarykey = NULL; INSERT INTO table SELECT * FROM tmptable_1; DROP TEMPORARY TABLE IF EXISTS tmptable_1; As a temp table, there should never be more than o...
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How to use glOrtho() in OpenGL?

...using the following code every time the window is resized: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0f, windowWidth, windowHeight, 0.0f, 0.0f, 1.0f); This will remap the OpenGL coordinates into the equivalent pixel values (X going from 0 to windowWidth and Y going from 0 to window...
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Is there an exponent operator in C#?

...h.Pow() is not an operator an thus has not the same usages as an operator ._. – Alexandre Daubricourt Dec 30 '18 at 13:35 add a comment  |  ...
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How to configure Git post commit hook

...the git notes 'build' (git show refs/notes/build): git diff --name-only SHA_build HEAD. your script can parse that list and decide if it needs to go on with the build. in any case, create/move your git notes 'build' to HEAD. May 2016: cwhsu points out in the comments the following possible url...
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Ternary Operator Similar To ?:

...or that we just defined: object T { val condition = true import Bool._ // yay! val x = condition ? "yes" | "no" } Have fun ;) share | improve this answer | ...