winq syntax

[0x1306a94]

The language of WCDB

Swift

The version of WCDB

2.1.6

The platform of WCDB

iOS

The installation of WCDB

Carthage

What's the issue?

Is it possible to support writing similar to NSCompoundPredicate? I used the following extension, and the generated sql should be illegal. I checked the test code of the Swift part in the repository, but couldn't find how to write this.

extension Collection where Element: ExpressionConvertible {
    func and() -> ExpressionConvertible {
        if self.isEmpty {
            return Expression(nilLiteral: ())
        }

        let sql = self.map { $0.asExpression().description }
            .joined(separator: " AND ")

        return Expression(stringLiteral: "(\(sql))")
    }

    func or() -> ExpressionConvertible {
        if self.isEmpty {
            return Expression(nilLiteral: ())
        }

        let sql = self.map { $0.asExpression().description }
            .joined(separator: " OR ")

        return Expression(stringLiteral: "(\(sql))")
    }
}

func test() {
    let conditions = [
        Order.Properties.orderId.in(table: "order") == Ticket.Properties.orderId.in(table: "ticket"),
        Ticket.Properties.ticketCode.in(table: "ticket") == "xxxx",
        Ticket.Properties.orderId.in(table: "ticket") == BindParameter(1),
    ]

    print("and: \(conditions.and().asExpression().description)")
    // and: '(order.orderId == ticket.orderId AND ticket.ticketCode == ''xxxx'' AND ticket.orderId == ?1)'
    print("or: \(conditions.or().asExpression().description)")
    // or: '(order.orderId == ticket.orderId OR ticket.ticketCode == ''xxxx'' OR ticket.orderId == ?1)'
}

For example, some dynamic conditions are very cumbersome to write using the following method

func test(orderId: String, ticketCode: String?) {
    var condition = Ticket.Properties.orderId == orderId
    if let ticketCode, !ticketCode.isEmpty {
        condition = condition && Ticket.Properties.ticketCode == ticketCode
    }

    print("sql: \(condition.description)")
}

[Qiuwen-chen]

Winq does not support raw string expression

[0x1306a94]

@Qiuwen-chen Can subsequent versions consider supporting NSCompoundPredicate?

[Qiuwen-chen]

@Qiuwen-chen Can subsequent versions consider supporting NSCompoundPredicate?

NO

[0x1306a94]

@Qiuwen-chen I mean support for NSCompoundPredicate-like syntax. For example, you can convert a list into a set of AND or OR

func test(orderId: String, ticketCode: String?) {
    var condition = Ticket.Properties.orderId == orderId
    var dynamicConditions: [ExpressionConvertible] = []
    if let ticketCode, !ticketCode.isEmpty {
        dynamicConditions.append(Ticket.Properties.ticketCode == ticketCode)
        dynamicConditions.append(Ticket.Properties.telephone == "dddd")
    }

    let finalCondition = condition && dynamicConditions.and()
    // sql: (orderId = 'dd' AND (ticketCode = 'xx' AND telephone = 'ddd'))

    // let finalCondition = condition && dynamicConditions.or()
    // sql: (orderId = 'dd' AND (ticketCode = 'xx' OR telephone = 'ddd'))

    print("sql: \(condition.description)")
}

func testPlaceholder(orderId: String?, ticketCode: String?) {
    var condition = WCDBSwift.Condition.Placeholder // sql:
    if let orderId, let ticketCode {
        condition =  condition && Ticket.Properties.orderId == orderId &&
        Ticket.Properties.ticketCode == ticketCode
        // sql: (orderId = 'xx' AND ticketCode = 'xx')
    }
}

[Qiuwen-chen]

@Qiuwen-chen I mean support for NSCompoundPredicate-like syntax. For example, you can convert a list into a set of AND or OR

func test(orderId: String, ticketCode: String?) {
    var condition = Ticket.Properties.orderId == orderId
    var dynamicConditions: [ExpressionConvertible] = []
    if let ticketCode, !ticketCode.isEmpty {
        dynamicConditions.append(Ticket.Properties.ticketCode == ticketCode)
        dynamicConditions.append(Ticket.Properties.telephone == "dddd")
    }

    let finalCondition = condition && dynamicConditions.and()
    // sql: (orderId = 'dd' AND (ticketCode = 'xx' AND telephone = 'ddd'))

    // let finalCondition = condition && dynamicConditions.or()
    // sql: (orderId = 'dd' AND (ticketCode = 'xx' OR telephone = 'ddd'))

    print("sql: \(condition.description)")
}

func testPlaceholder(orderId: String?, ticketCode: String?) {
    var condition = WCDBSwift.Condition.Placeholder // sql:
    if let orderId, let ticketCode {
        condition =  condition && Ticket.Properties.orderId == orderId &&
        Ticket.Properties.ticketCode == ticketCode
        // sql: (orderId = 'xx' AND ticketCode = 'xx')
    }
}

It seems that you can do it outside of wcdb

[0x1306a94]

@Qiuwen-chen It just doesn't work? That's why it needs support in wcdb! Although this can be achieved through the following extension, Expression(nilLiteral: ()) will output NULL and Expression(stringLiteral: "") will output ''

extension Collection where Element: ExpressionConvertible {
    func and() -> ExpressionConvertible {
        if self.isEmpty {
            return Expression(nilLiteral: ())
        }

        let finalExpression = self.reduce(Expression(nilLiteral: ())) { $0 && $ 1 }        
        return finalExpression
    }

    func or() -> ExpressionConvertible {
        if self.isEmpty {
            return Expression(nilLiteral: ())
        }

        let finalExpression = self.reduce(Expression(nilLiteral: ())) { $0 || $ 1 }        
        return finalExpression
    }
}

[Qiuwen-chen]

You need a empty expression, may be you can try Expression(booleanLiteral: true)

[0x1306a94]

@Qiuwen-chen

• This can be achieved by the following expansion, but it will produce a lot of nested brackets
• It would be better if wcdb itself could support this

• In addition, I noticed that the latest version 2.1.7 already supports the OHOS platform. Does this mean that the 2.1.7 version C++ API can be fully used on the OHOS platform?

  extension Collection where Element: ExpressionConvertible {
  func and() -> ExpressionConvertible? {
      guard let first = self.first else { return nil }
      guard count > 1 else { return first }
  
      let remainder = dropFirst()
      let finalExpression = remainder.reduce(first.asExpression()) { $0 && $1 }
      return finalExpression
  }
  
  func or() -> ExpressionConvertible? {
      guard let first = self.first else { return nil }
      guard count > 1 else { return first }
  
      let remainder = dropFirst()
      let finalExpression = remainder.reduce(first.asExpression()) { $0 || $1 }
  
      return finalExpression
  }
  }

[Qiuwen-chen]

Yes, WCDB C++ can be fully used on the OHOS platform. NSCompoundPredicate-like syntax is not a normal sql expression, I don't want to support this officially.