Python one-liner: converting JSON to YAML

I’ve been playing with the Titan graph database lately; it’s hella cool, super powerful, and has a great ecosystem. One tool in the Titan toolbox is a REST interface called Rexster.

You can check to see that it’s up and what it’s serving up by curl-ing one of its endpoints.

# curl localhost:8182/graphs/graph
{"version":"2.5.0","name":"graph","graph":"titangraph[cassandrathrift:[127.0.0.1]]","features":{"isWrapper":false,"supportsVertexProperties":true,"supportsMapProperty":true,"supportsUniformListProperty":true,"supportsIndices":false,"ignoresSuppliedIds":true,"supportsFloatProperty":true,"supportsPrimitiveArrayProperty":true,"supportsEdgeIndex":false,"supportsKeyIndices":true,"supportsDoubleProperty":true,"isPersistent":true,"supportsVertexIteration":true,"supportsEdgeProperties":true,"supportsSelfLoops":true,"supportsDuplicateEdges":true,"supportsSerializableObjectProperty":true,"supportsEdgeIteration":true,"supportsVertexIndex":false,"supportsIntegerProperty":true,"supportsBooleanProperty":true,"supportsMixedListProperty":true,"supportsEdgeRetrieval":true,"supportsTransactions":true,"supportsThreadedTransactions":true,"supportsStringProperty":true,"supportsVertexKeyIndex":false,"supportsEdgeKeyIndex":false,"supportsLongProperty":true},"readOnly":false,"type":"com.thinkaurelius.titan.graphdb.database.StandardTitanGraph","queryTime":0.213622,"upTime":"0[d]:00[h]:28[m]:25[s]","extensions":[{"op":"GET","namespace":"tp","name":"gremlin","description":"evaluate an ad-hoc Gremlin script for a graph.","href":"http://localhost:8182/graphs/graph/tp/gremlin","title":"tp:gremlin","parameters":[{"name":"rexster.showTypes","description":"displays the properties of the elements with their native data type (default is false)"},{"name":"language","description":"the gremlin language flavor to use (default is groovy)"},{"name":"params","description":"a map of parameters to bind to the script engine"},{"name":"load","description":"a list of 'stored procedures' to execute prior to the 'script' (if 'script' is not specified then the last script in this argument will return the values"},{"name":"returnTotal","description":"when set to true, the full result set will be iterated and the results returned (default is false)"},{"name":"rexster.returnKeys","description":"an array of element property keys to return (default is to return all element properties)"},{"name":"rexster.offset.start","description":"start index for a paged set of data to be returned"},{"name":"rexster.offset.end","description":"end index for a paged set of data to be returned"},{"name":"script","description":"the Gremlin script to be evaluated"}]},{"op":"POST","namespace":"tp","name":"gremlin","description":"evaluate an ad-hoc Gremlin script for a graph.","href":"http://localhost:8182/graphs/graph/tp/gremlin","title":"tp:gremlin","parameters":[{"name":"rexster.showTypes","description":"displays the properties of the elements with their native data type (default is false)"},{"name":"language","description":"the gremlin language flavor to use (default is groovy)"},{"name":"params","description":"a map of parameters to bind to the script engine"},{"name":"load","description":"a list of 'stored procedures' to execute prior to the 'script' (if 'script' is not specified then the last script in this argument will return the values"},{"name":"returnTotal","description":"when set to true, the full result set will be iterated and the results returned (default is false)"},{"name":"rexster.returnKeys","description":"an array of element property keys to return (default is to return all element properties)"},{"name":"rexster.offset.start","description":"start index for a paged set of data to be returned"},{"name":"rexster.offset.end","description":"end index for a paged set of data to be returned"},{"name":"script","description":"the Gremlin script to be evaluated"}]}

Ugly. Python to the rescue.

#!/usr/bin/env python

import simplejson
import sys
import yaml

print yaml.dump(simplejson.loads(str(sys.stdin.read())), default_flow_style=False)

Basically a one-liner.

# curl localhost:32791/graphs/graph | python json2yaml.py 
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  3581    0  3581    0     0   552k      0 --:--:-- --:--:-- --:--:--  582k
extensions:
- description: evaluate an ad-hoc Gremlin script for a graph.
  href: http://localhost:8182/graphs/graph/tp/gremlin
  name: gremlin
  namespace: tp
  op: GET
  parameters:
  - description: displays the properties of the elements with their native data type
      (default is false)
    name: rexster.showTypes
  - description: the gremlin language flavor to use (default is groovy)
    name: language
  - description: a map of parameters to bind to the script engine
    name: params
  - description: a list of 'stored procedures' to execute prior to the 'script' (if
      'script' is not specified then the last script in this argument will return
      the values
    name: load
  - description: when set to true, the full result set will be iterated and the results
      returned (default is false)
    name: returnTotal
  - description: an array of element property keys to return (default is to return
      all element properties)
    name: rexster.returnKeys
  - description: start index for a paged set of data to be returned
    name: rexster.offset.start
  - description: end index for a paged set of data to be returned
    name: rexster.offset.end
  - description: the Gremlin script to be evaluated
    name: script
  title: tp:gremlin
- description: evaluate an ad-hoc Gremlin script for a graph.
  href: http://localhost:8182/graphs/graph/tp/gremlin
  name: gremlin
  namespace: tp
  op: POST
  parameters:
  - description: displays the properties of the elements with their native data type
      (default is false)
    name: rexster.showTypes
  - description: the gremlin language flavor to use (default is groovy)
    name: language
  - description: a map of parameters to bind to the script engine
    name: params
  - description: a list of 'stored procedures' to execute prior to the 'script' (if
      'script' is not specified then the last script in this argument will return
      the values
    name: load
  - description: when set to true, the full result set will be iterated and the results
      returned (default is false)
    name: returnTotal
  - description: an array of element property keys to return (default is to return
      all element properties)
    name: rexster.returnKeys
  - description: start index for a paged set of data to be returned
    name: rexster.offset.start
  - description: end index for a paged set of data to be returned
    name: rexster.offset.end
  - description: the Gremlin script to be evaluated
    name: script
  title: tp:gremlin
features:
  ignoresSuppliedIds: true
  isPersistent: true
  isWrapper: false
  supportsBooleanProperty: true
  supportsDoubleProperty: true
  supportsDuplicateEdges: true
  supportsEdgeIndex: false
  supportsEdgeIteration: true
  supportsEdgeKeyIndex: false
  supportsEdgeProperties: true
  supportsEdgeRetrieval: true
  supportsFloatProperty: true
  supportsIndices: false
  supportsIntegerProperty: true
  supportsKeyIndices: true
  supportsLongProperty: true
  supportsMapProperty: true
  supportsMixedListProperty: true
  supportsPrimitiveArrayProperty: true
  supportsSelfLoops: true
  supportsSerializableObjectProperty: true
  supportsStringProperty: true
  supportsThreadedTransactions: true
  supportsTransactions: true
  supportsUniformListProperty: true
  supportsVertexIndex: false
  supportsVertexIteration: true
  supportsVertexKeyIndex: false
  supportsVertexProperties: true
graph: titangraph[cassandrathrift:[127.0.0.1]]
name: graph
queryTime: 0.31277
readOnly: false
type: com.thinkaurelius.titan.graphdb.database.StandardTitanGraph
upTime: 0[d]:00[h]:31[m]:27[s]
version: 2.5.0

I love Python. YAML ain’t bad, either.

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