nested json problem
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Hello,
I try to use the rijksmuseum api. This gives json back for 10 paintings and the json looks like this :
and
but that does not work. Is there a better way to make this work. and if so, can someone give me a example how to make this work. This is my first project that I try to make after doing the MOOC course. Regards, Roelof
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Re: nested json problem
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Hi/Dag Roelof,
In a first approach I would not start by trying to map to actual domain objects (you can do that later), I would start by using NeoJSONObject, which is quite flexible and user friendly. Consider the following example: (NeoJSONObject fromString: '{ "elapsedMilliseconds": 164, "count": 359, "artObjects": [ { "links": { "self": "https://www.rijksmuseum.nl/api/nl/collection/SK-C-5", "web": "https://www.rijksmuseum.nl/nl/collection/SK-C-5" }, "id": "nl-SK-C-5", "objectNumber": "SK-C-5", "title": "Schutters van wijk II onder leiding van kapitein Frans Banninck Cocq, bekend als de ‘Nachtwacht’", "hasImage": true, "principalOrFirstMaker": "Rembrandt Harmensz. van Rijn", "longTitle": "Schutters van wijk II onder leiding van kapitein Frans Banninck Cocq, bekend als de ‘Nachtwacht’, Rembrandt Harmensz. van Rijn, 1642", "showImage": true, "permitDownload": true, "webImage": { "guid": "92253da1-794d-49f4-9e3c-e4c160715f53", "offsetPercentageX": 50, "offsetPercentageY": 100, "width": 2500, "height": 2034, "url": "http://lh6.ggpht.com/wwx2vAS9DzFmmyeZefPjMtmCNOdjD80gvkXJcylloy40SiZOhdLHVddEZLBHtymHu53TcvqJLYZfZF7M-uvoMmG_wSI=s0" }, "headerImage": { "guid": "29a2a516-f1d2-4713-9cbd-7a4458026057", "offsetPercentageX": 50, "offsetPercentageY": 50, "width": 1920, "height": 460, "url": "http://lh5.ggpht.com/SgH3Qo-vYI8GGm7-b-Qt6lXgsCAIoU2VDRwO5LYSBVNhhbZCetcvc88ZPi518MTy0MHDrna4X4ZC1ymxVJVpzps8gqw=s0" }, "productionPlaces": [] } ] }') artObjects first atPath: #(webImage url) First try to execute the expression inside the braces, and look at the result using the inspector. Unknown accessor automatically get translated to at: message sends (in this case, at: #artObjects). Using #atPath: you get the equivalent of webImage.url if you understand what I mean. To use NeoJSONObject in an actual API call, you could do ZnClient new contentReader: [ :entity | NeoJSONObject fromString: entity contents ]; url: '...'; get. Sven > On 5 Nov 2018, at 19:32, Roelof Wobben <[hidden email]> wrote: > > Hello, > > I try to use the rijksmuseum api. > This gives json back for 10 paintings and the json looks like this : > > { > > > "elapsedMilliseconds": 164, > > > "count": 359, > > > "artObjects": [ > > > { > > > "links": { > > > "self": "https://www.rijksmuseum.nl/api/nl/collection/SK-C-5", > > > "web": "https://www.rijksmuseum.nl/nl/collection/SK-C-5" > > > }, > > > "id": "nl-SK-C-5", > > > "objectNumber": "SK-C-5", > > > "title": "Schutters van wijk II onder leiding van kapitein Frans Banninck Cocq, bekend als de ‘Nachtwacht’", > > > "hasImage": true, > > > "principalOrFirstMaker": "Rembrandt Harmensz. van Rijn", > > > "longTitle": "Schutters van wijk II onder leiding van kapitein Frans Banninck Cocq, bekend als de ‘Nachtwacht’, Rembrandt Harmensz. van Rijn, 1642", > > > "showImage": true, > > > "permitDownload": true, > > > "webImage": { > > > "guid": "92253da1-794d-49f4-9e3c-e4c160715f53", > > > "offsetPercentageX": 50, > > > "offsetPercentageY": 100, > > > "width": 2500, > > > "height": 2034, > > > "url": "http://lh6.ggpht.com/wwx2vAS9DzFmmyeZefPjMtmCNOdjD80gvkXJcylloy40SiZOhdLHVddEZLBHtymHu53TcvqJLYZfZF7M-uvoMmG_wSI=s0" > > > }, > > > "headerImage": { > > > "guid": "29a2a516-f1d2-4713-9cbd-7a4458026057", > > > "offsetPercentageX": 50, > > > "offsetPercentageY": 50, > > > "width": 1920, > > > "height": 460, > > > "url": "http://lh5.ggpht.com/SgH3Qo-vYI8GGm7-b-Qt6lXgsCAIoU2VDRwO5LYSBVNhhbZCetcvc88ZPi518MTy0MHDrna4X4ZC1ymxVJVpzps8gqw=s0" > > > }, > > > "productionPlaces": [] > > > }, > > > // more results... > > > ] > } > > > Artobjects is the part that I want to use because that is the part that contains data from 10 paintings. > > I have tried to parse it like this : > > > Painting class >> fromJSON: json [ > | instance | > instance := self new. > instance > title: (json at: 'title'); > painter: (json at: 'principalOrFirstMaker'); > imageUrl: ((json at: 'webImage') at: 'url'). > ^ instance > ] > and > > PaintingCollection class >> fromJSON: json [ > | instance artObjects | > instance := self new. > artObjects := json at: #artObjects. > artObjects > do: [ :eachArtObject | instance addPainting: (Painting fromJSON: eachArtObject) ]. > ^ instance > ] > > but that does not work. > > Is there a better way to make this work. > and if so, can someone give me a example how to make this work. > This is my first project that I try to make after doing the MOOC course. > > Regards, > > Roelof > |
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In reply to this post by Roelof
I use this code to try to read things:
Op 5-11-2018 om 22:33 schreef Erik Stel: Roelof, What does not work in your code? How do you call PaintingCollection>>fromJSON: ? >From what I see this code could work if used like (replace URL with actual URL): -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html |
Re: nested json problem
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> On 5 Nov 2018, at 22:41, Roelof Wobben <[hidden email]> wrote: > > I use this code to try to read things: > > json paintingCollection | > json := (NeoJSONReader fromString: (ZnEasy get: ' > https://www.rijksmuseum.nl/api/nl/collection?key=14OGzuak&format=json&type=schilderij&toppieces=True > ') contents). > paintingCollection := PaintingCollection fromJSON: json. > paintingCollection inspect > > and now suddenly I see a message that #add: is sent to nill I am guessing here: is the instance variable holding your collection inside PaintingCollection initialized to an actual collection before you #add: to it in #addPainting: ? You could initialize it lazily if you want. > Roelof > > > > > > Op 5-11-2018 om 22:33 schreef Erik Stel: >> Roelof, >> >> What does not work in your code? How do you call >> PaintingCollection>>fromJSON: ? >> >> >From what I see this code could work if used like (replace URL with actual >> URL): >> >> >> >> >> >> >> >> -- >> Sent from: >> http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html >> >> >> >> > |
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Problem has solved.
I had the instance variable to instance := self new. instead of instance := self basicNew. Roelof Op 5-11-2018 om 22:50 schreef Sven Van Caekenberghe: > >> On 5 Nov 2018, at 22:41, Roelof Wobben <[hidden email]> wrote: >> >> I use this code to try to read things: >> >> json paintingCollection | >> json := (NeoJSONReader fromString: (ZnEasy get: ' >> https://www.rijksmuseum.nl/api/nl/collection?key=14OGzuak&format=json&type=schilderij&toppieces=True >> ') contents). >> paintingCollection := PaintingCollection fromJSON: json. >> paintingCollection inspect >> >> and now suddenly I see a message that #add: is sent to nill > I am guessing here: is the instance variable holding your collection inside PaintingCollection initialized to an actual collection before you #add: to it in #addPainting: ? You could initialize it lazily if you want. > >> Roelof >> >> >> >> >> >> Op 5-11-2018 om 22:33 schreef Erik Stel: >>> Roelof, >>> >>> What does not work in your code? How do you call >>> PaintingCollection>>fromJSON: ? >>> >>> >From what I see this code could work if used like (replace URL with actual >>> URL): >>> >>> >>> >>> >>> >>> >>> >>> -- >>> Sent from: >>> http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html >>> >>> >>> >>> > > |
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