pinejs-getting-started-bug-repro

THIS ISSUE IS NOW FIXED As of balena-io-modules/odata-to-abstract-sql/pull/26

1. Rationale

When running the "getting started" example from the PineJS repro, I observed an error when running a command which was supposed to succeed:

$ curl -X POST \
	-d name=testdevice \
	-d note=testnote \
	-d type=raspberry \
	http://localhost:1337/example/device

"Bind value cannot be undefined: Bind,device,id"

To make sure that this deviation from expectations wasn't a result of my machine being somehow a variable, I containerized the simple app using a Dockerfile adapted from that used in resin-api, which runs a node app as a systemd service.

2. Observe the error

# builds and runs the docker container hosting the PSQL DB and the pineJS app
./build-and-run.sh

# runs the curl commands which cause the error to appear
./reproduce.sh

3. Analysis

Code reference for the below: pinejs/src/sbvr-api/sbvr-utils.coffee#L166

Code of interest:

166 exports.resolveOdataBind = resolveOdataBind = (odataBinds, value) ->
167		if _.isObject(value) and value.bind?
168			[dataType, value] = odataBinds[value.bind]
169		return value
170
171	getAndCheckBindValues = (vocab, odataBinds, bindings, values) ->
172		sqlModelTables = sqlModels[vocab].tables
173		Promise.map bindings, (binding) ->
174			if binding[0] is 'Bind'
175				if _.isArray(binding[1])
176					[tableName, fieldName] = binding[1]
177
178					referencedName = tableName + '.' + fieldName
179					value = values[referencedName]
180					if value is undefined
181						value = values[fieldName]
182
183				value = resolveOdataBind(odataBinds, value)
		...
208 	if value is undefined
209			throw new Error("Bind value cannot be undefined: #{binding}")

simply put

Inside getAndCheckBindValues(), when fieldname = "id", after the _.isArray(binding[1]) block, value is undefined at line 208, causing the error to throw.

At a high level, value ends up undefined for fieldname = "id" since:

1. "id" is not in request.values (appears to be the values supplied in the PUT request)

2. although the data which corresponds to "id" (1) is in request.odataBinds, (appears to be fallback values inferred from the OData URL?), the function exports.resolveOdataBind(odataBinds, value) doesn't have the right logic to find that info, or isn't given a parameter in the right format.

Detailed trace

The bindings param is always at least (that is, if we send no data with our PUT request):

"bindings":[
    [
        "Bind",
            [
                "device",
                "id"
            ]
    ]
]

bindings, as a parameter to getAndCheckBindValues(), comes from a request object created in pinejs/src/sbvr-api/parse-uri.coffee. In that file,

(note: this is more like pseudocode, not actual lines)

request.odataBinds = memoizedParseOdata(url).binds

request.values = requestBody.data

So, it appears in L178-181 try to find device.id or id among the keys of values, but it's not there. Why? Because request.values is simply the request body. id or device.id would only be there if we put them there after parsing the OData URL. That failing, we look it up in request.odataBinds.

There is therefore one big question:

The odataBinds object (fig 1) seems to be of the correct format to allow the code for exports.resolveOdataBind(odataBinds, value) (fig 2) to find the value for fieldname = "id", but it wants value to be an object like (fig 3), which it won't be, since value will always be a string, looking at the format of values, from which it comes (fig 4)

fig 1.

"odataBinds": [
    [
        "Real",
        2
    ]
],

fig 2.

exports.resolveOdataBind = resolveOdataBind = (odataBinds, value) ->
	if _.isObject(value) and value.bind?
		[dataType, value] = odataBinds[value.bind]
	return value

fig 3.

{
    ...
    "bind": 0,
}

fig 4.

"values":{
    "name":"testdevice",
    "note":"updatednote",
    "type":"raspberry"
},