ArangoDB AQL Updating Strange Attribute Names - arangodb

Question

In arangodb I have a Lookup Table as per below:
{
'49DD3A82-2B49-44F5-A0B2-BD88A32EDB13' = 'Human readable value 1',
'B015E210-27BE-4AA7-83EE-9F754F8E469A' = 'Human readable value 2',
'BC54CF8A-BB18-4E2C-B333-EA7086764819' = 'Human readable value 3',
'8DE15947-E49B-4FDC-89EE-235A330B7FEB' = 'Human readable value n'
}
I have documents in a seperate collection such as this which have non human readable attribute and value pairs as per "details" below:
{
"ptype": {
"name": "BC54CF8A-BB18-4E2C-B333-EA7086764819",
"accuracy": 9.6,
"details": {
"49DD3A82-2B49-44F5-A0B2-BD88A32EDB13": "B015E210-27BE-4AA7-83EE-9F754F8E469A",
"8DE15947-E49B-4FDC-89EE-235A330B7FEB": true,
}
}
}
I need to update the above document by looking up the human readable values out of the lookup table and I also need to update the non-human readable attributes with the readable attribute names also found in the lookup table.
The result should look like this:
{
"ptype": {
"name": "Human readable value 3",
"accuracy": 9.6,
"details": {
"Human readable value 1": "Human readable value 2",
"Human readable value n": true,
}
}
}
so ptype.name and ptype.details are updated with values from the lookup table.

Answer 1

This query should help you see how a LUT (Look Up Table) can be used.
One cool feature of AQL is that you can do a LUT query and assign it's value to a variable with the LET command, and then access the contents of that LUT later.
See if this example helps:
LET lut = {
'aaa' : 'Apples',
'bbb' : 'Bananas',
'ccc' : 'Carrots'
}
LET garden = [
{
'size': 'Large',
'plant_code': 'aaa'
},
{
'size': 'Medium',
'plant_code': 'bbb'
},
{
'size': 'Small',
'plant_code': 'ccc'
}
]
FOR doc IN garden
RETURN {
'size': doc.size,
'vegetable': lut[doc.plant_code]
}
The result of this query is:
[
{
"size": "Large",
"vegetable": "Apples"
},
{
"size": "Medium",
"vegetable": "Bananas"
},
{
"size": "Small",
"vegetable": "Carrots"
}
]
You'll notice in the bottom query that actually returns data, it's referring to the LUT by using the doc.plant_code as the look up key.
This is much more performant that performing subqueries there, because if you had 100,000 garden documents you don't want to perform a supporting query 100,000 times to work out the name of the plant_code.
If you wanted to confirm that you could find a value in the LUT, you could optionally have your final query in this format:
FOR doc IN garden
RETURN {
'size': doc.size,
'vegetable': (lut[doc.plant_code] ? lut[doc.plant_code] : 'Unknown')
}
This optional way to return the value for vegetable uses an inline if/then/else, where if the value is not found in the lut, it will return the value 'Unknown'.
Hope this helps you with your particular use case.