feat: add pallets/consts endpoint

[marshacb]

Summary: An endpoint that returns the constants for a given pallet

/pallets/{palletId}/consts

Query Params

• at: Which block to query, it will default to the latest finalized block. Accepts a hash or blocknumber
• onlyIds: boolean to return only the Id of each constant instead of the entirety of each constant

Sample response for /pallets/democracy/consts?onlyIds=true

{
	"at": {
		"hash": "0xf178fd381cbfbea8d3df1c6579cc918eb1dedeee6281cf3ee006a40e0139e469",
		"height": "14046577"
	},
	"pallet": "democracy",
	"palletIndex": "14",
	"items": [
		"EnactmentPeriod",
		"LaunchPeriod",
		"VotingPeriod",
		"VoteLockingPeriod",
		"MinimumDeposit",
		"InstantAllowed",
		"FastTrackVotingPeriod",
		"CooloffPeriod",
		"MaxVotes",
		"MaxProposals",
		"MaxDeposits",
		"MaxBlacklisted"
	]
}

/pallets/{palletId}/consts/{constItemId}

Query Params

• at: Which block to query, it will default to the latest finalized block. Accepts a hash or blocknumber
• metadata: boolean to choose whether to include an consts' metadata in the response

Sample response for /pallets/democracy/consts/InstantAllowed

{
	"at": {
		"hash": "0xd4b121ad968b133091b837292d7a73d77234b07be0073ad5b97a95b192d8ae3f",
		"height": "14046588"
	},
	"pallet": "democracy",
	"palletIndex": "14",
	"constantsItem": "instantAllowed"
}

[TarikGul]

👍

[Imod7]

I see that this if...else statement keeps growing and I was wondering if it would a good idea to replace this conditionals with a lookup table or an object lookup ? since the only thing that changes is the name of the function called.
I was checking some articles to find as references :

• js patterns - lookup tables
• js - objects for lookups
• js ts code - lookups

Maybe it makes it also more readable and maintainable ? Just an idea because I used that in C in the past and I think it is quite fast but I am not sure in Typescript (performance wise).

[TarikGul]

I don't think this is necessary. A lookup table would require a few abstractions, and performance isn't really going to get affected here. if...else is acceptable IMO. We know the fixed size of this if else so I don't think its going to grow much more.

That being said the only other option I would see for readability is a switch statement.

[Imod7]

Looks Great!