invalid argument type in call to function 'ATTRIBUTES()' in ArangoDB - arangodb

Question

I have stored my Data in the give formate in AreangoDB, My collection name in DSP:
"data": {
"1": [ {"db_name": "DSP"}, {"rel": "2"} ],
"2": [ {"rel_name": "DataSource"}, {"tuple": "201"}, {"tuple": "202"}, {"tuple": "203"} ],
"201": [ {"src_id": "Pos201510070"}, {"src_name": "Postgres"}, {"password": "root"}, {"host": "localhost"}, {"created_date": "20151007"}, {"user_name": "postgres"}, {"src_type": "Structured"}, {"db_name": "postgres"}, {"port": "None"} ],
"202": [ {"src_id": "pos201510060"}, {"src_name": "Postgres"},{"password": "root"}, {"host": "localhost"}, {"created_date": "20151006"}, {"user_name": "postgres"}, {"src_type": "Structured"}, {"db_name": "DSP"}, {"port": "5432"} ],
"203": [ {"src_id": "pos201510060"}, {"src_name": "Postgres"}, {"password": "root"}, {"host": "localhost"}, {"created_date": "20151006"}, {"user_name": "postgres"},{"src_type": "Structured"},{"db_name": "maindb"},{"port": "5432"} ]
}
I am executing a query with the above data in the following format:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p)
FOR attribute IN attributes
LET key = ATTRIBUTES(attribute)[0]
LET value = attribute[key]
RETURN { subject: attribute, predicate: key, object: value }
When I submit my query to ArangoDB, it returns the response as:
Warnings:
[1542], 'invalid argument type in call to function 'ATTRIBUTES()''
[1542], 'invalid argument type in call to function 'ATTRIBUTES()''
[1542], 'invalid argument type in call to function 'ATTRIBUTES()''
[1542], 'invalid argument type in call to function 'ATTRIBUTES()''
Result:
[
{
"subject": "data",
"predicate": null,
"object": null
},
{
"subject": "_id",
"predicate": null,
"object": null
},
{
"subject": "_rev",
"predicate": null,
"object": null
},
{
"subject": "_key",
"predicate": null,
"object": null
}
]
Please tell me what is the problem with this query, and why the answer is like the above..I am working in ArangoDB-2.7.3-win64.
Thanks

Answer 1

Let me demonstrate how to construct such a complex query digging deep into nested data structures. I start out taking the outer parts of the query, to have an inner result:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p)
FOR attribute IN attributes
RETURN attribute
which gives me:
[
"data",
"_rev",
"_key",
"_id"
]
So lets dive deeper into the next layer. I guess you're only interested in the values present underneath data key right? so we pick p.data:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR attribute IN attributes
RETURN attribute
which then gives me the keys for your next inner array:
[
"203",
"202",
"201",
"2",
"1"
]
We now explore what we find attached to these nodes:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR oneAttribute IN attributes
LET keys = p.data[oneAttribute]
RETURN keys
Its Again an array, which we need to iterate into using a FOR loop over keys:
[
[
{
"src_id" : "pos201510060"
},
{
"src_name" : "Postgres"
}, ...
We add this additional FOR-loop:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR oneAttribute IN attributes
LET keys = p.data[oneAttribute]
FOR key IN keys
RETURN key
we get the inner most objects:
[
{
"src_id" : "pos201510060"
},
{
"src_name" : "Postgres"
},
{
"password" : "root"
},
...
You wanted to use the ATTRIBUTES function, but the objects only have one member, so we can access [0]:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR oneAttribute IN attributes
LET keys = p.data[oneAttribute]
FOR key IN keys
LET keyAttributes=ATTRIBUTES(key)
RETURN keyAttributes
Which gives us the object keys, one per inner most object:
[
[
"src_id"
],
[
"src_name"
],
We inspect whether we now get only the object keys of the inner most structure; we pick the variable names a little more clever than above:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR oneAttribute IN attributes
LET pairs = p.data[oneAttribute]
FOR onePair IN pairs
LET pairKey=ATTRIBUTES(onePair)[0]
RETURN pairKey
YES:
[
"src_id",
"src_name",
"password",
"host",
...
So now its time to construct the results object as you wanted them:
FOR p IN NestedDSP
LET attributes = ATTRIBUTES(p.data)
FOR oneAttribute IN attributes
LET pairs = p.data[oneAttribute]
FOR onePair IN pairs
LET pairKey=ATTRIBUTES(onePair)[0]
RETURN { subject: oneAttribute, predicate: pairKey, object: onePair[pairKey] }
The subject is the number identifying the outermost item, the predicate is the object key, and the object is the value in it:
[
{
"subject" : "203",
"predicate" : "src_id",
"object" : "pos201510060"
},
{
"subject" : "203",
"predicate" : "src_name",
"object" : "Postgres"
}
Which is hopefully what you wanted?