prodio/web/src/partials/datalanguage.html

Simplified project management

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  <h2>Data Query Language</h2>
  <p>To aid with the intgration of most Data Stores a common query language
    must exist and must be defined. To keep with the ability to store queries
    as JSON a structure is borrowed from that of Sift and MongoDB. All
    operations listed below must be implmented for a data store to be considered
    acceptable. In some cases, such as the memory store or the LevelDB store,
    sift may be directly utilized to traverse and filter the results before
    returning them to the caller.</p>
  <p>The following was taken from the Sift documentation and reduced to fit
    the larger audience.</p>

  <h3>$in</h3>
  <p>array value must be $in the given query:</p>
  <p>Intersecting two arrays:</p>
  <pre><code>  //filtered: ['Brazil']
  filter({ $in: ['Costa Rica','Brazil'] }, ['Brazil','Haiti','Peru','Chile']);</code></pre>
  <p>Here's another example. This acts more like the $or operator:</p>
  <pre><code>  filter({ location: { $in: ['Costa Rica','Brazil'] } }, { name: 'Craig', location: 'Brazil' });</code></pre>

  <h3>$nin</h3>
  <p>Opposite of $in:</p>
  <pre><code>  //filtered: ['Haiti','Peru','Chile']
  filter({ $nin: ['Costa Rica','Brazil'] }, ['Brazil','Haiti','Peru','Chile']);</code></pre>

  <h3>$exists</h3>
  <p>Checks if whether a value exists:</p>
  <pre><code>  //filtered: ['Craig','Tim']
  filter({ $exists: true }, ['Craig',null,'Tim']);</code></pre>
  <p>You can also filter out values that don't exist</p>
  <pre><code>  //filtered: [{ name: 'Craig', city: 'Minneapolis' }]
  filter({ city: { $exists: false } }, [ { name: 'Craig', city: 'Minneapolis' }, { name: 'Tim' }]);</code></pre>

  <h3>$gte</h3>
  <p>Checks if a number is >= value:</p>
  <pre><code>  //filtered: [2, 3]
  filter({ $gte: 2 }, [0, 1, 2, 3]);</code></pre>

  <h3>$gt</h3>
  <p>Checks if a number is > value:</p>
  <pre><code>  //filtered: [3]
  filter({ $gt: 2 }, [0, 1, 2, 3]);</code></pre>

  <h3>$lte</h3>
  <p>Checks if a number is <= value.</p>
  <pre><code>  //filtered: [0, 1, 2]
  filter({ $lte: 2 }, [0, 1, 2, 3]);</code></pre>

  <h3>$lt</h3>
  <p>Checks if number is < value.</p>
  <pre><code>  //filtered: [0, 1]
  filter({ $lt: 2 }, [0, 1, 2, 3]);</code></pre>

  <h3>$eq</h3>
  <p>Checks if query == value. Note that $eq can be omitted. For $eq, and $neq</p>
  <pre><code>  //filtered: [{ state: 'MN' }]
  filter({ state: {$eq: 'MN' }}, [{ state: 'MN' }, { state: 'CA' }, { state: 'WI' });</code></pre>
  <p>Or:</p>
  <pre><code>  //filtered: [{ state: 'MN' }]
  filter({ state: 'MN' }, [{ state: 'MN' }, { state: 'CA' }, { state: 'WI' });</code></pre>

  <h3>$ne</h3>
  <p>Checks if query != value.</p>
  <pre><code>  //filtered: [{ state: 'CA' }, { state: 'WI'}]
  filter({ state: {$ne: 'MN' }}, [{ state: 'MN' }, { state: 'CA' }, { state: 'WI' });</code></pre>

  <h3>$all</h3>
  <p>values must match everything in array:</p>
  <pre><code>  //filtered: [ { tags: ['books','programming','travel' ]} ]
  filter({ tags: {$all: ['books','programming'] }}, [
  { tags: ['books','programming','travel' ] },
  { tags: ['travel','cooking'] } ]);</code></pre>

  <h3>$and</h3>
  <p>ability to use an array of expressions. All expressions must test true.</p>
  <pre><code>  //filtered: [ { name: 'Craig', state: 'MN' }]
  filter({ $and: [ { name: 'Craig' }, { state: 'MN' } ] }, [
  { name: 'Craig', state: 'MN' },
  { name: 'Tim', state: 'MN' },
  { name: 'Joe', state: 'CA' } ]);</code></pre>

  <h3>$or</h3>
  <p>OR array of expressions.</p>
  <pre><code>  //filtered: [ { name: 'Craig', state: 'MN' }, { name: 'Tim', state: 'MN' }]
  filter({ $or: [ { name: 'Craig' }, { state: 'MN' } ] }, [
  { name: 'Craig', state: 'MN' },
  { name: 'Tim', state: 'MN' },
  { name: 'Joe', state: 'CA' } ]);</code></pre>

  <h3>$nor</h3>
  <p>opposite of or:</p>
  <pre><code>  //filtered: [ { name: 'Tim', state: 'MN' }, { name: 'Joe', state: 'CA' }]
  filter({ $nor: [ { name: 'Craig' }, { state: 'MN' } ] }, [
  { name: 'Craig', state: 'MN' },
  { name: 'Tim', state: 'MN' },
  { name: 'Joe', state: 'CA' } ]);</code></pre>

  <h3>$regex</h3>
  <p>Matches values based on the given regular expression</p>
  <pre><code>  filter({ $regex: /^f/i, $nin: ["frank"] }, ["frank", "fred", "sam", "frost"]); // ["fred", "frost"]</code></pre>

  <h3>$not</h3>
  <p>Not expression:</p>
  <pre><code>  filter({$not:{$in:['craig','tim']}}, ['craig','tim','jake']); //['jake']
  filter({$not:{$size:5}}, ['craig','tim','jake']); //['tim','jake']</code></pre>
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