Core Data fetch using a predicate

-1

I have two core data entities, one is called Person and the other is Codes. A Person has a one-to-many relationship with Codes.

enter image description here

I want to retrieve all the Codes for a particular Person and have the following function:

static func fetchCodes(person: Person) -> [Codes]? {

    let context = getContext()

    let fetchRequest : NSFetchRequest<Codes> = Codes.fetchRequest()

    let sortDescriptor = NSSortDescriptor(key: #keyPath(Codes.number), ascending: true)

    fetchRequest.sortDescriptors = [sortDescriptor]

    //print("person in fetchCodes=(person.first)")

    fetchRequest.predicate = NSPredicate(format: "whosAccount == %@", person)

    do {

        let codes: [Codes] = try context.fetch(Codes.fetchRequest())

        //print("Codes count from fetchCodes: (codes.count)")

        return codes

    } catch {

        return nil

    }

}

I have checked that the argument person is in fact the correct Person that I want to retrieve codes for but the result returns all Codes for all Persons. What am I missing?

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

What you are missing is a typo: context.fetch(Codes.fetchRequest()) should be context.fetch(fetchRequest).

– pbasdf
Nov 20 '18 at 22:22

@pbasdf:Thank you. That was the problem

– pdoak
Nov 21 '18 at 9:21

add a comment |

-1

I have two core data entities, one is called Person and the other is Codes. A Person has a one-to-many relationship with Codes.

enter image description here

I want to retrieve all the Codes for a particular Person and have the following function:

static func fetchCodes(person: Person) -> [Codes]? {

    let context = getContext()

    let fetchRequest : NSFetchRequest<Codes> = Codes.fetchRequest()

    let sortDescriptor = NSSortDescriptor(key: #keyPath(Codes.number), ascending: true)

    fetchRequest.sortDescriptors = [sortDescriptor]

    //print("person in fetchCodes=(person.first)")

    fetchRequest.predicate = NSPredicate(format: "whosAccount == %@", person)

    do {

        let codes: [Codes] = try context.fetch(Codes.fetchRequest())

        //print("Codes count from fetchCodes: (codes.count)")

        return codes

    } catch {

        return nil

    }

}

I have checked that the argument person is in fact the correct Person that I want to retrieve codes for but the result returns all Codes for all Persons. What am I missing?

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

What you are missing is a typo: context.fetch(Codes.fetchRequest()) should be context.fetch(fetchRequest).

– pbasdf
Nov 20 '18 at 22:22

@pbasdf:Thank you. That was the problem

– pdoak
Nov 21 '18 at 9:21

add a comment |

-1

I have two core data entities, one is called Person and the other is Codes. A Person has a one-to-many relationship with Codes.

enter image description here

I want to retrieve all the Codes for a particular Person and have the following function:

static func fetchCodes(person: Person) -> [Codes]? {

    let context = getContext()

    let fetchRequest : NSFetchRequest<Codes> = Codes.fetchRequest()

    let sortDescriptor = NSSortDescriptor(key: #keyPath(Codes.number), ascending: true)

    fetchRequest.sortDescriptors = [sortDescriptor]

    //print("person in fetchCodes=(person.first)")

    fetchRequest.predicate = NSPredicate(format: "whosAccount == %@", person)

    do {

        let codes: [Codes] = try context.fetch(Codes.fetchRequest())

        //print("Codes count from fetchCodes: (codes.count)")

        return codes

    } catch {

        return nil

    }

}

I have checked that the argument person is in fact the correct Person that I want to retrieve codes for but the result returns all Codes for all Persons. What am I missing?

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

I have two core data entities, one is called Person and the other is Codes. A Person has a one-to-many relationship with Codes.

enter image description here

I want to retrieve all the Codes for a particular Person and have the following function:

static func fetchCodes(person: Person) -> [Codes]? {

    let context = getContext()

    let fetchRequest : NSFetchRequest<Codes> = Codes.fetchRequest()

    let sortDescriptor = NSSortDescriptor(key: #keyPath(Codes.number), ascending: true)

    fetchRequest.sortDescriptors = [sortDescriptor]

    //print("person in fetchCodes=(person.first)")

    fetchRequest.predicate = NSPredicate(format: "whosAccount == %@", person)

    do {

        let codes: [Codes] = try context.fetch(Codes.fetchRequest())

        //print("Codes count from fetchCodes: (codes.count)")

        return codes

    } catch {

        return nil

    }

}

I have checked that the argument person is in fact the correct Person that I want to retrieve codes for but the result returns all Codes for all Persons. What am I missing?

swift core-data

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

edited Nov 23 '18 at 11:06

wvteijlingen

7,87012543

asked Nov 20 '18 at 18:47

pdoak

339211

asked Nov 20 '18 at 18:47

pdoak

339211

asked Nov 20 '18 at 18:47

pdoak

339211

What you are missing is a typo: context.fetch(Codes.fetchRequest()) should be context.fetch(fetchRequest).

– pbasdf
Nov 20 '18 at 22:22

@pbasdf:Thank you. That was the problem

– pdoak
Nov 21 '18 at 9:21

add a comment |

What you are missing is a typo: context.fetch(Codes.fetchRequest()) should be context.fetch(fetchRequest).

– pbasdf
Nov 20 '18 at 22:22

@pbasdf:Thank you. That was the problem

– pdoak
Nov 21 '18 at 9:21

What you are missing is a typo: context.fetch(Codes.fetchRequest()) should be context.fetch(fetchRequest).

– pbasdf
Nov 20 '18 at 22:22

@pbasdf:Thank you. That was the problem

– pdoak
Nov 21 '18 at 9:21

add a comment |

2 Answers
2

active

oldest

votes

You don’t need a fetch or a predicate, you access the relation as an attribute

let codes = person.codes

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

Thank you. That is a much neater solution. This returns a Set which looks like this:First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: { code = RY6; number = 1; whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; })). How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

add a comment |

Since you have the Person you don't need to fetch any data, just get the codes from the relationship

static func fetchCodes(person: Person) -> [Codes] {

    return person.codes

}

answered Nov 20 '18 at 18:53

vadian

144k13154170

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

You don’t need a fetch or a predicate, you access the relation as an attribute

let codes = person.codes

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

Thank you. That is a much neater solution. This returns a Set which looks like this:First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: { code = RY6; number = 1; whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; })). How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

add a comment |

You don’t need a fetch or a predicate, you access the relation as an attribute

let codes = person.codes

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

Thank you. That is a much neater solution. This returns a Set which looks like this:First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: { code = RY6; number = 1; whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; })). How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

add a comment |

You don’t need a fetch or a predicate, you access the relation as an attribute

let codes = person.codes

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

You don’t need a fetch or a predicate, you access the relation as an attribute

let codes = person.codes

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

answered Nov 20 '18 at 18:53

Joakim Danielson

7,4003624

Thank you. That is a much neater solution. This returns a Set which looks like this:First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: { code = RY6; number = 1; whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; })). How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

add a comment |

Thank you. That is a much neater solution. This returns a Set which looks like this:First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: { code = RY6; number = 1; whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; })). How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

Thank you. That is a much neater solution. This returns a Set which looks like this:

First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: {     code = RY6;     number = 1;     whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; }))

. How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

Thank you. That is a much neater solution. This returns a Set which looks like this:

First code is: Optional(<Codes: 0x600002136440> (entity: Codes; id: 0x61480dce0533d92b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Codes/p225> ; data: {     code = RY6;     number = 1;     whosAccount = "0x61480dce3c73d90b <x-coredata://A2B634E4-E136-48E1-B2C5-82B6B68FBE44/Person/p4>"; }))

. How do I just extract the code and the number element? Also, I will need to sort the Set based on the number element.

– pdoak
Nov 21 '18 at 9:40

I think you should read the documentation for Set but you can iterate over a set to access all the Codes objects. Set is unordered but there are sorted methods you can call that returns a sorted array.

– Joakim Danielson
Nov 21 '18 at 11:07

I am fairly new to Xcode/swift and have read the Set documentation but don't understand how to filter the set returned by person.codes to retrieve the code = RY6 if I filter on number = 1

– pdoak
Nov 21 '18 at 13:55

add a comment |

Since you have the Person you don't need to fetch any data, just get the codes from the relationship

static func fetchCodes(person: Person) -> [Codes] {

    return person.codes

}

answered Nov 20 '18 at 18:53

vadian

144k13154170

add a comment |

Since you have the Person you don't need to fetch any data, just get the codes from the relationship

static func fetchCodes(person: Person) -> [Codes] {

    return person.codes

}

answered Nov 20 '18 at 18:53

vadian

144k13154170

add a comment |

Since you have the Person you don't need to fetch any data, just get the codes from the relationship

static func fetchCodes(person: Person) -> [Codes] {

    return person.codes

}

answered Nov 20 '18 at 18:53

vadian

144k13154170

Since you have the Person you don't need to fetch any data, just get the codes from the relationship

static func fetchCodes(person: Person) -> [Codes] {

    return person.codes

}

answered Nov 20 '18 at 18:53

vadian

144k13154170

answered Nov 20 '18 at 18:53

vadian

144k13154170

answered Nov 20 '18 at 18:53

vadian

144k13154170

answered Nov 20 '18 at 18:53

vadian

144k13154170

add a comment |

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