58 lines
2.0 KiB
Markdown
58 lines
2.0 KiB
Markdown
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# jmespath.js
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[](https://travis-ci.org/jmespath/jmespath.js)
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jmespath.js is a javascript implementation of JMESPath,
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which is a query language for JSON. It will take a JSON
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document and transform it into another JSON document
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through a JMESPath expression.
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Using jmespath.js is really easy. There's a single function
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you use, `jmespath.search`:
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```
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> var jmespath = require('jmespath');
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> jmespath.search({foo: {bar: {baz: [0, 1, 2, 3, 4]}}}, "foo.bar.baz[2]")
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2
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```
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In the example we gave the ``search`` function input data of
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`{foo: {bar: {baz: [0, 1, 2, 3, 4]}}}` as well as the JMESPath
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expression `foo.bar.baz[2]`, and the `search` function evaluated
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the expression against the input data to produce the result ``2``.
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The JMESPath language can do a lot more than select an element
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from a list. Here are a few more examples:
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```
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> jmespath.search({foo: {bar: {baz: [0, 1, 2, 3, 4]}}}, "foo.bar")
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{ baz: [ 0, 1, 2, 3, 4 ] }
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> jmespath.search({"foo": [{"first": "a", "last": "b"},
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{"first": "c", "last": "d"}]},
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"foo[*].first")
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[ 'a', 'c' ]
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> jmespath.search({"foo": [{"age": 20}, {"age": 25},
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{"age": 30}, {"age": 35},
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{"age": 40}]},
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"foo[?age > `30`]")
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[ { age: 35 }, { age: 40 } ]
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```
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## More Resources
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The example above only show a small amount of what
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a JMESPath expression can do. If you want to take a
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tour of the language, the *best* place to go is the
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[JMESPath Tutorial](http://jmespath.org/tutorial.html).
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One of the best things about JMESPath is that it is
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implemented in many different programming languages including
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python, ruby, php, lua, etc. To see a complete list of libraries,
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check out the [JMESPath libraries page](http://jmespath.org/libraries.html).
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And finally, the full JMESPath specification can be found
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on the [JMESPath site](http://jmespath.org/specification.html).
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