In order to dummy up a test in node.js, I need data to populate a testing CouchDB database. Specifically, I am testing some code that creates statistics plots (in R) and then saves them to a doc as attachments. So for my tests, I need at least one document with its PNG attachments already in place.
I couldn’t find a simple “howto” for this on the Internet, so here’s a note to my future self.
First of all, the CouchDB docs are great, and curl is your friend. Curl lets you set the headers. In this case, I don’t want HTML to come back, I want a valid JSON document, so (in typical belt-and-suspenders style) I specify both the content type and the accept header parameters to be application/json as follows:
curl -H 'Content-Type: application/json' \ -H 'Accept: application/json' \ 127.0.0.1:5984/my%2freal%2fdatabase/801447?attachments=true> 801447.json
The returned document has encoded the binary PNG files as JSON fields, in accordance with the CouchDB specs:
{"_id":"801447","_rev":"55-8e15623f21dce9ed556cfe96b9c85a8e",
"2012":{"properties":[
{"name":"SERFAS CLUB",
"cal_pm":"R3.688",
"abs_pm":40.920000000000001705,
"latitude_4269":"33.880712",
"longitude_4269":"-117.613596",
"lanes":1,
"segment_length":"0.316",
"freeway":91,
"direction":"E",
"vdstype":"ML",
"district":8,
"versions":["2012-12-04","2012-12-12"],
"geojson":{"type":"Point",
"crs":{"type":"name",
"properties":{"name":"EPSG:4326"}},
"coordinates":[-117.62000000000000455,
33.881000000000000227]}
}
]},
"_attachments":{
"801447_2012_raw_004.png":{
"content_type":"image/png",
"revpos":53,"digest":"md5-tF2vnhvNw7pLHlK31DVNUw==",
"data":"iVBORw0KGgoAAAANSUhEUgAABkAAAAGQCAIAAAB59ztRAAAgAElEQVR4
nOzdeYAUxd038Opr7tmbXVYRXEQEOeSSy3greK1sIJqIRImaRONLPBJDTFBRDGp4Dl
GjicYj4oEJyimsyHItyiWPoCAYjQQQuZZll71m5+r3jwrtOEd1z0xP9TDz/fzDzNBb
v6ruquqemupqQVVVAgAAAAAAAAAAkK1EqzMAAAAAAAAAAADAggEsAAAAAAAAAADIah
jAAgAAAAAAAACArIYBLAAAAAAAAAAAyGoYwAIAAAAAAAAAgKyGASwAAAAAAAAAAMhq
GMACAAAAAAAAAICshgEsAAAAAAAAAADIahjAAgAAAAAAAACArIYBLAAAAAAAAAAAyG
oYwAIAAAAAAAAAgKyGASwAAAAAAAAAAMhqGMACAAAAAAAAAICshgEsAAAAAAAAAADI
ahjAAgAAAAAAAACArIYBLAAAAAAAAAAAyGoYwAIAAAAAAAAAgKyGASwAAAAAAAAAAM
hqGMACAAAAAAAAAICshgEsAAA ..."
Lovely binary-to-hex, looking good.
To verify that the returned document is actually valid json, I use the command line some more (and I’m not sure which Linux library installed this, but there are several JSON pretty printers and verifiers out there):
james@emma files[bug/fixplots]$ json_verify< 801451.json JSON is valid
Then to use the document in my test, all I have to do is read it in and send it off:
function put_json_file(file,couchurl,cb){
var db_dump = require(file) // in node you can require json too!
superagent.post(couchurl)
.type('json')
.send(db_dump)
.end(function(e,r){
should.not.exist(e)
should.exist(r)
return cb(e)
})
return null
}
To see that in action, I put my various CouchDB-related utilities in a file here, and then my actual test has a before job that creates the CouchDB database and populates it, and a corresponding after task that deletes the temporary database.
Contour Line 