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

8,25112544

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

8,25112544

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

8,25112544

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

8,25112544

asked Nov 20 '18 at 18:47

pdoak

339211

edited Nov 23 '18 at 11:06

wvteijlingen

8,25112544

asked Nov 20 '18 at 18:47

pdoak

339211

edited Nov 23 '18 at 11:06

wvteijlingen

8,25112544

edited Nov 23 '18 at 11:06

wvteijlingen

8,25112544

edited Nov 23 '18 at 11:06

wvteijlingen

8,25112544

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

8,0913724

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

146k13157175

add a comment |

Your Answer

StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});

}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53399579%2fcore-data-fetch-using-a-predicate%23new-answer', 'question_page');
}
);

Post as a guest

Name

Required, but never shown

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

8,0913724

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

8,0913724

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

8,0913724

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

8,0913724

answered Nov 20 '18 at 18:53

Joakim Danielson

8,0913724

answered Nov 20 '18 at 18:53

Joakim Danielson

8,0913724

answered Nov 20 '18 at 18:53

Joakim Danielson

8,0913724

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

146k13157175

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

146k13157175

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

146k13157175

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

146k13157175

answered Nov 20 '18 at 18:53

vadian

146k13157175

answered Nov 20 '18 at 18:53

vadian

146k13157175

answered Nov 20 '18 at 18:53

vadian

146k13157175

add a comment |

draft saved

draft discarded

Thanks for contributing an answer to Stack Overflow!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

Search This Blog

Ufyukyu