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POHow can I test for an empty Breeze predicate?
 

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  1. POHow can I test for an empty Breeze predicate?
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    <p>I'm using Breeze to filter data requested on the client. My code looks a little like this:</p> <p><strong>Client - Creating Filter Predicate</strong></p> <pre><code>var predicates = []; var criteriaPredicate = null; $.each(selectedFilterCriteria(), function (index, item) { criteriaPredicate = (index == 0) ? breeze.Predicate.create('criteriaId', breeze.FilterQueryOp.Equals, item) : criteriaPredicate.or('criteriaId', breeze.FilterQueryOp.Equals, item); if (breeze.Predicate.isPredicate(criteriaPredicate)) { predicates.push(criteriaPredicate); } // Repeat for X Filter Criteria var filter = breeze.Predicate.and(predicates); return context.getAll(filter, data); </code></pre> <p><strong>Client - Context Query</strong></p> <pre><code>function getAll(predicate, dataObservable) { var query = breeze.EntityQuery.from('Data'); if (breeze.Predicate.isPredicate(predicate)) { query = query.where(predicate); } return manager.executeQuery(query).then(success).fail(failure); } </code></pre> <p><strong>Issue</strong></p> <p>I'm having an issue with the request because, if there are no filters set, I apply an "empty" predicate (due to the <code>var filter = breeze.Predicate.and([])</code> line) resulting in a request like <code>http://mysite/api/app/Data?$filter=</code>. The request is an invalid OData query since the value of the $filter argument cannot be empty.</p> <p>Is there a good way for me to check for an empty predicate? I know I can refactor my client code to not use a predicate unless there is at least one filterable item, but I thought I would check first to see if I overlooked some property or method on the Breeze Predicate.</p>
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    1. This table or related slice is empty.
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
 

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