SwiftUI Sqlite如何存儲復雜對象

如何你有大量圖片或者復雜文本需要存儲，sqlite 的Blob類型將是你最佳的選擇

代碼

 public func addNote(_  note:Note) -> Int64 {
        let notes = Table("notes")
        let body=Expression<SQLite.Blob>("body")
        let sec_id=Expression<Int64>("section_id")
        let date=Expression<Double>("date")
        let cloud_id=Expression<String>("cloud_id")
        let locked=Expression<Bool>("locked")
        let checksum=Expression<Int>("checksum")
        let bytes=note.toBytes()
        let cks=Note.checkSum(bytes: bytes)
        
        let i = notes.insert(body <- SQLite.Blob(bytes: bytes),
                             sec_id <- note.section,
                             date <- note.date! ,
                             cloud_id <- note.cloud_id!,
                             checksum <- Int(cks),
                             locked<-note.locked)
        do {
            let rowid=try db?.run(i)
            return rowid ?? -1
        }catch {
            print("Error info: \(error)")
        }
        return -1
    }

數據截圖

image.png

定義了NoteObject父類

public class NoteObject :  Identifiable {
    public var id:Int=0
    private var buffer:[UInt8]?
    
    init() {
    }
    func getId() ->Int {
        return id
    }
    func toBytes() -> [UInt8]? {
        return buffer
    }
    
    static func bytesToInteger<Type>(_ from: [UInt8]) -> Type where Type: BinaryInteger {
        return from.withUnsafeBufferPointer({
            UnsafeRawPointer($0.baseAddress!).load(as: Type.self)
        })
    }
    
    func toByteArray<Type>(_ value: Type) -> [UInt8] {
        var unsafeValue = value
        
        return withUnsafePointer(to: &unsafeValue) {
            return $0.withMemoryRebound(to: UInt8.self, capacity: MemoryLayout<Type>.size, { pointer in
                return [UInt8](UnsafeBufferPointer(start: pointer, count: MemoryLayout<Type>.size))
            })
        }
    }
    
    static func readInt(_ bytes:  [UInt8], offset: inout Int) -> Int? {
        guard bytes.count >= offset + MemoryLayout<Int>.size else { return nil }
        
        let bytesForInt: [UInt8] = Array(bytes[offset..<offset + MemoryLayout<Int>.size])
        let value: Int = bytesToInteger(bytesForInt)
        
        offset += MemoryLayout<Int>.size
        
        return value
    }
    
    static func readArray(_ bytes:  [UInt8], offset: inout Int, capacity: Int, endOffset: Int) -> [UInt8]? {
        
        if offset < endOffset {
            let arr=bytes[offset...(offset+capacity-1)]
            offset += arr.count
            return Array(arr)
        }
        return nil
    }
    
    func debugString() {
        print("element:\(type(of: self))")
        if self is NoteText {
            print(":"+(self as! NoteText).text)
        } else if self is NoteImage {
            print(":\((self as! NoteImage).image!.size)")
        } else if self is NoteTable {
            let table=(self as! NoteTable)
            print(":\(table.text),\(table.nrow),\(table.ncol)")
        }
    }
}

NoteObject的子類

public class NoteText : NoteObject {
    
    var text:String=""
    var desc:String=""
    
    init( text:String) {
        self.text=text
    }
    
    init(newid: Int, text:String) {
        super.init()
        id=newid
        self.text=text
        self.desc=text
    }
    
    init (pk:Int,bytes:[UInt8],bytes2:[UInt8]) {
        super.init()
        id=pk
        text=String(data: Data(bytes),encoding: .utf8)!
        if bytes2.count > 0 {
            desc=String(data: Data(bytes2),encoding: .utf8)!
        }
    }
    
    override func toBytes() -> [UInt8]? {
        var array = Array(text.utf8)
        array.insert(contentsOf: toByteArray(array.count), at: 0)
        array.insert(contentsOf: toByteArray(ObjectTags.text.rawValue), at: 0)
        
        let array2 = Array(desc.utf8)
        array.append(contentsOf: toByteArray(array2.count))
        array.append(contentsOf: array2)
        
        return array
    }
    
    
    
}

public class NoteImage : NoteObject {
    
    var image:UIImage?
    var width:CGFloat=159
    var height:CGFloat=150
    
    init( image: UIImage) {
        self.image=image
    }
    
    init(newid: Int, image: UIImage) {
        super.init()
        id=newid
        self.image=image
    }
    
    init(pk:Int, bytes:[UInt8]) {
        super.init()
        id=pk
        var offset = 0
        
        let w=NoteObject.readInt(bytes, offset: &offset)
        let h=NoteObject.readInt(bytes, offset: &offset)
        if w! > 0 {
            width=CGFloat(w!)
        }
        if h! > 0 {
            height=CGFloat(h!)
        }
        let arr_bytes=NoteObject.readArray(bytes, offset: &offset, capacity: bytes.count-16, endOffset: bytes.count)
        image=UIImage(data: Data.fromDatatypeValue(Blob(bytes: arr_bytes!)))!
    }
    
    override func toBytes() -> [UInt8]? {
        let dimg = image!.jpegData(compressionQuality: 1.0)
        var array=[UInt8]()
        array.reserveCapacity((dimg!.count+1+8+8+8))
        array.append(contentsOf: toByteArray(ObjectTags.image.rawValue))
        array.append(contentsOf: toByteArray(dimg!.count+16))
        array.append(contentsOf: toByteArray(Int(width)))
        array.append(contentsOf: toByteArray(Int(height)))
        array.append(contentsOf: dimg!)
        return array
        
    }
}

public class NoteTable : NoteObject {
    
    var nrow:UInt8=0
    var ncol:UInt8=0
    var text:String=""
    
    init( ncol:UInt8,nrow:UInt8, text:String) {
        self.ncol=ncol
        self.nrow=nrow
        self.text=text
    }
    
    init(newid: Int, ncol:UInt8,nrow:UInt8, text:String) {
        super.init()
        id=newid
        self.ncol=ncol
        self.nrow=nrow
        self.text=text
    }
    
    init (pk:Int,bytes:[UInt8]) {
        super.init()
        id=pk
        self.ncol=bytes[0]
        self.nrow=bytes[1]
        text=String(data: Data(bytes[2...bytes.count-1]),encoding: .utf8)!
    }
    
    override func toBytes() -> [UInt8]? {
        var array = Array(text.utf8)
        let all_length=array.count+2
        array.insert(contentsOf: toByteArray(nrow), at: 0)
        array.insert(contentsOf: toByteArray(ncol), at: 0)
        array.insert(contentsOf: toByteArray(all_length), at: 0)
        array.insert(contentsOf: toByteArray(ObjectTags.table.rawValue), at: 0)
        return array
    }
}

來源

• https://github.com/indaos/DaoNotes

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