rjson: Convert `list` to JSON-like string compatible with Cypher DSL

Question

Let's have:

desired_output="{a:'1', b:'foo'}"
D = list(a=1, b="foo")

Then:

out = toJSON(D)
out
"{\"a\":1,\"b\":\"foo\"}"

identical(out, desired_output) # FALSE

Is there a better function f (other than gsub) so that this holds?

identical( f(toJSON(D)), desired_output) == TRUE

Using cat just prints to the screen:

cat(toJSON(D))
{"a":1,"b":"foo"}

Background:

The desired_output format of the string is required for dynamically constructing cypher/Neo4j graph database queries using RNeo4j package for a call such as:

# match node n with properties a=1 and b="foo"
RNeo4j::cypher(graph, query="MATCH (n{a:'1', b:'foo'}) RETURN n") 

Answer 1

This works on your example and hopefully more general cases:

gsub("',", "', ",                             # adds spaces after commas
   gsub('"', "'",                             # replaces " with '
      gsub('"([^"]+)":', "\\1:",              # removes " around key names
         toJSON(rapply(D, as.character)))))   # puts " around numerics
# [1] "{a:'1', b:'foo'}"