Parsing JSON to CSV in Groovy - json

Question

I'm trying to parse json file to csv. Could you help?
example json:
{
"expand": "schema,names",
"startAt": 0,
"maxResults": 50,
"total": 21,
"issues": [
{
"expand": "operations,versionedRepresentations",
"id": "217580",
"self": "issue/217580",
"key": "ART-4070",
"fields": {"summary": "#[ART] Pre.3 Verification \\"S\\""}
},
{
"expand": "operations,versionedRepresentations",
"id": "217579",
"self": "issue/217579",
"key": "ART-4069",
"fields": {"summary": "Verification \\"C\\""}
},
{
"expand": "operations,versionedRepresentations",
"id": "217577",
"self": "issue/217577",
"key": "ART-4068",
"fields": {"summary": "#[ART] Enum type"}
}
]
}
result csv should be like:
key;summary
ART-4070;#[ART] Pre.3 Verification \"S\"
ART-4069;Verification \"C\"
ART-4068;#[ART] Enum type
I've tried such a code:
import groovy.json.*
def jsonSlurper = new JsonSlurper()
def json = '''
{
"expand": "schema,names",
"startAt": 0,
"maxResults": 50,
"total": 21,
"issues": [
{
"expand": "operations,versionedRepresentations",
"id": "217580",
"self": "issue/217580",
"key": "ART-4070",
"fields": {"summary": "#[ART] Pre.3 Verification \\"S\\""}
},
{
"expand": "operations,versionedRepresentations",
"id": "217579",
"self": "issue/217579",
"key": "ART-4069",
"fields": {"summary": "Verification \\"C\\""}
},
{
"expand": "operations,versionedRepresentations",
"id": "217577",
"self": "issue/217577",
"key": "ART-4068",
"fields": {"summary": "#[ART] Enum type"}
}
]
}
'''
def obj = jsonSlurper.parse(json)
def columns = obj.issues*.keySet().flatten().unique()
// remove nulls
def encode = { e -> e == null ? '' : e }
// Print all the column names
println columns.collect { c -> encode( c ) }.join( ';' )
// create all the rows
println obj.issues.collect { row ->
// A row at a time
columns.collect { colName -> encode( row[ colName ] ) }.join( ';' )
}.join( '\n' )
but result is wrong:
expand;id;self;key;fields
operations,versionedRepresentations;217580;issue/217580;ART-4070;[summary:#[ART] Pre.3 Verification "S"]
operations,versionedRepresentations;217579;issue/217579;ART-4069;[summary:Verification "C"]
operations,versionedRepresentations;217577;issue/217577;ART-4068;[summary:#[ART] Enum type]
how can i extract only what i want from json file? I need only two columns:key,summary and values for them.

Answer 1

You want to extract only specific information from your list of issues
and you need different strategies to extract those. So I'd use
a "configuration" to describe the extraction (see the map config
below). Then the code is quite close to your original one (extracted
some common code etc)
import groovy.json.*
def config = [ // header -> extractor
"key": { it.key },
"summary": { it.fields.summary }
]
def encode(e) { // help with nulls; quote the separator
(e ?: "").replaceAll(";", "\\;")
}
def csvLine(items) { // write items as "CSV"
println(items.collect{ encode it }.join(";"))
}
// main
def obj = new JsonSlurper().parse("data.json" as File)
csvLine(config.keySet())
obj.issues.each{ issue ->
csvLine(config.values().collect{ f -> f issue })
}