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Automatically encoding data to JSON with Leaf (for embedding into scripts)
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| 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 | |
| } | |
| } | |
| } |
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| // ... | |
| var leafTag = LeafTagConfig.default() | |
| leafTag.use(JSONTag(), as: "json") | |
| services.register(leafTag) | |
| // ... |
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| 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) | |
| } | |
| } |
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| // ... | |
| 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) | |
| } | |
| // ... |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>JSON tag example</title> | |
| </head> | |
| <body> | |
| <h1>Here's some JSON data</h1> | |
| <pre>#json(params)</pre> | |
| </body> | |
| </html> |
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