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POknockout validation unique in list
 

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    <p>I'm trying to validate an entry in a list to be unique from all other entries in the list using ko.validation, but I'm having issues with validation running when it shouldn't.</p> <p>I have an editable list (a <code>ko.observableArray</code>), and each item in that array is a view model with a <code>ko.observable</code> on it:</p> <pre><code>var vm = function (data) { var self = this; self.items = ko.observableArray(); _.each(data.words, function (word) { self.items.push(new listItemVm({parent: self, word: word.word})); }); }; var listItemVm = function (data) { var self = this; self.parent = data.parent; self.word = ko.observable(data.word); }; </code></pre> <p>Then I add some validation to <code>listItemVm.word</code> ko.observable. I want each one to be unique:</p> <pre><code>var listItemVm = function (data) { var self = this; self.parent = data.parent; self.word = ko.observable(data.word).extend({ validation: { validator: function (name, params) { console.log("validating " + name); // word we are editing must be different from all other words // uncommenting this next line causes the behaviour // I would expect because params.parent.items() // is not called //return true; var allWords = params.parent.items(); // exclude current view model we are editing var otherWordViewModels = _.filter(allWords, function (row) { return row !== params.currentRow; }); var otherWords = _.map(otherWordViewModels, function (item) { return item.word(); }); return !_.contains(otherWords, name); }, message: 'Must be unique', params: { currentRow: self, parent: self.parent } } }); }; </code></pre> <p>I give it some data, and wrap it in some HTML: <a href="http://jsfiddle.net/9kw75/3/" rel="nofollow">http://jsfiddle.net/9kw75/3/</a></p> <p>Now, this does <em>work</em> - the validation runs correctly and shows invalid when the values of the two inputs are equal - but have a look in the console on that fiddle. Why does the validation routine run three five times on load, and why do both fields validate when just one value updates?</p> <ul> <li><strong>On page load</strong> <ul> <li><em>Expected</em>: validation runs once for each input field.</li> <li><em>Actual</em>: validation runs three times for one input, and twice for the other.</li> </ul></li> <li><strong>On value update (either input field)</strong> <ul> <li><em>Expected</em>: validation runs for altered input field only</li> <li><em>Actual</em>: validation runs for both input fields</li> </ul></li> </ul> <p>It's worth noting that this strange behaviour is only observed after reading <code>params.parent.items()</code> in the validator. If the return is commented out, the behaviour I would expect is observed.</p>
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    1. COI don't understand - that fiddle is working perfect?
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    2. CO@PWKad I don't think it is. The messages display correctly, but open the console and look at when the validation routine runs. Updated question to make this clearer.
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