vzsg/1_JSONTag.swift

## 1_JSONTag.swift
import Leaf
import Foundation

final class JSONTag: TagRenderer {
    private let encoder = JSONEncoder()

    func render(tag: TagContext) throws -> EventLoopFuture<TemplateData> {
        try tag.requireNoBody()
        try tag.requireParameterCount(1)
        let json = try encoder.encode(tag.parameters[0])
        return tag.future(TemplateData.string(String(data: json, encoding: .utf8) ?? ""))
    }
}

extension TemplateData: Encodable {
    public func encode(to encoder: Encoder) throws {
        if isNull {
            var svc = encoder.singleValueContainer()
            try svc.encodeNil()
            return
        }

        if let array = self.array {
            var ukc = encoder.unkeyedContainer()
            try ukc.encode(contentsOf: array)
            return
        }

        if let dict = self.dictionary {
            var kvc = encoder.container(keyedBy: String.self)
            try dict.forEach {
                try kvc.encode($1, forKey: $0)
            }
        }

        // FIXME: this will encode the String "5" as the number 5. This seems
        // to be less harmful than encoding everything as Strings...
        // There seems to be no way around the fuzziness of TemplateData.
        if let int = self.int {
            var svc = encoder.singleValueContainer()
            try svc.encode(int)
            return
        }

        if let double = self.double {
            var svc = encoder.singleValueContainer()
            try svc.encode(double)
            return
        }

        if let string = self.string {
            var svc = encoder.singleValueContainer()
            try svc.encode(string)
            return
        }

        if let data = self.data, let string = String(data: data, encoding: .utf8) {
            var svc = encoder.singleValueContainer()
            try svc.encode(string)
            return
        }
    }
}

## 2_configure.swift
// ...
    var leafTag = LeafTagConfig.default()
    leafTag.use(JSONTag(), as: "json")
    services.register(leafTag)
// ...

## 3_String+CodingKey.swift
import Foundation

extension String: CodingKey {
    public init?(stringValue: String) {
        self.init(stringLiteral: stringValue)
    }

    public init?(intValue: Int) {
        self.init(intValue)
    }

    public var stringValue: String {
        return self
    }

    public var intValue: Int? {
        return Int(self)
    }
}

## 4_routes.swift
// ...

    router.get("jsonleaf") { req -> Future<View> in
        struct Context: Encodable {
            let params: ChartParams
        }

        struct ChartParams: Encodable {
            let labels: [String]
            let values: [[Int]]
        }

        let context = Context(params: ChartParams(labels: ["Jan", "Feb", "Mar"], values: [[1,3,4], [2,3,4], [5,4,3]]))

        return try req.view()
            .render("test", context)
    }

// ...

## 5_test.leaf
<!DOCTYPE html>
<html>
<head>
  <title>JSON tag example</title>
</head>

<body>
  <h1>Here's some JSON data</h1>
  <pre>#json(params)</pre>
</body>

</html>
	import Leaf
	import Foundation

	final class JSONTag: TagRenderer {
	private let encoder = JSONEncoder()

	func render(tag: TagContext) throws -> EventLoopFuture<TemplateData> {
	try tag.requireNoBody()
	try tag.requireParameterCount(1)
	let json = try encoder.encode(tag.parameters[0])
	return tag.future(TemplateData.string(String(data: json, encoding: .utf8) ?? ""))
	}
	}

	extension TemplateData: Encodable {
	public func encode(to encoder: Encoder) throws {
	if isNull {
	var svc = encoder.singleValueContainer()
	try svc.encodeNil()
	return
	}

	if let array = self.array {
	var ukc = encoder.unkeyedContainer()
	try ukc.encode(contentsOf: array)
	return
	}

	if let dict = self.dictionary {
	var kvc = encoder.container(keyedBy: String.self)
	try dict.forEach {
	try kvc.encode($1, forKey: $0)
	}
	}

	// FIXME: this will encode the String "5" as the number 5. This seems
	// to be less harmful than encoding everything as Strings...
	// There seems to be no way around the fuzziness of TemplateData.
	if let int = self.int {
	var svc = encoder.singleValueContainer()
	try svc.encode(int)
	return
	}

	if let double = self.double {
	var svc = encoder.singleValueContainer()
	try svc.encode(double)
	return
	}

	if let string = self.string {
	var svc = encoder.singleValueContainer()
	try svc.encode(string)
	return
	}

	if let data = self.data, let string = String(data: data, encoding: .utf8) {
	var svc = encoder.singleValueContainer()
	try svc.encode(string)
	return
	}
	}
	}
	// ...
	var leafTag = LeafTagConfig.default()
	leafTag.use(JSONTag(), as: "json")
	services.register(leafTag)
	// ...
	import Foundation

	extension String: CodingKey {
	public init?(stringValue: String) {
	self.init(stringLiteral: stringValue)
	}

	public init?(intValue: Int) {
	self.init(intValue)
	}

	public var stringValue: String {
	return self
	}

	public var intValue: Int? {
	return Int(self)
	}
	}
	// ...

	router.get("jsonleaf") { req -> Future<View> in
	struct Context: Encodable {
	let params: ChartParams
	}

	struct ChartParams: Encodable {
	let labels: [String]
	let values: [[Int]]
	}

	let context = Context(params: ChartParams(labels: ["Jan", "Feb", "Mar"], values: [[1,3,4], [2,3,4], [5,4,3]]))

	return try req.view()
	.render("test", context)
	}

	// ...
	<!DOCTYPE html>
	<html>
	<head>
	<title>JSON tag example</title>
	</head>

	<body>
	<h1>Here's some JSON data</h1>
	<pre>#json(params)</pre>
	</body>

	</html>