Interroger les utilisateurs Parse avec React Native

interroger les utilisateurs dans parse sur react native introduction certaines applications react native doivent gérer directement les utilisateurs de votre application ou au moins être capables de lister un sous ensemble spécifique d'entre eux parse dispose d'outils de requête puissants qui peuvent également être utilisés pour vos utilisateurs dans votre application de médias sociaux, par exemple dans ce guide, vous apprendrez à utiliser parse query parse query pour effectuer des requêtes d'utilisateurs réalistes dans votre application react native en utilisant le sdk js de parse prérequis pour compléter ce tutoriel, vous aurez besoin de une application react native créée et connectée à back4app objectif construire une fonctionnalité d'interrogation d'utilisateurs en utilisant parse pour une application react native 1 comprendre la classe parse query toute opération de requête parse utilise le parse query parse query type d'objet, qui vous aidera à récupérer des données spécifiques de votre base de données tout au long de votre application il est crucial de savoir qu'un parse query parse query ne se résoudra qu'après avoir appelé une méthode de récupération (comme parse query find parse query find ou parse query get parse query get ), donc une requête peut être configurée et plusieurs modificateurs peuvent être chaînés avant d'être réellement appelés pour créer un nouveau parse query parse query , vous devez passer en paramètre le parse object parse object sous classe souhaitée, qui est celle qui contiendra les résultats de votre requête un exemple pour ce cas d'utilisation du guide ( parse user parse user ) peut être vu ci dessous javascript 1 // this will create your query 2 const parsequery = new parse query(parse user); 3 // the query will resolve only after calling this method 5 const queryresult = await parsequery find();1 // this will create your query 2 const parsequery parse query = new parse query(parse user); 3 // the query will resolve only after calling this method 4 const queryresult \[parse user] = await parsequery find(); vous pouvez en savoir plus sur la parse query parse query classe ici dans la documentation officielle https //parseplatform org/parse sdk js/api/master/parse query html 2 effectuer des requêtes utilisateur pertinentes examinons maintenant quelques requêtes pertinentes que vous pourriez avoir besoin d'effectuer lors de la gestion ou de l'affichage des utilisateurs dans votre application tout d'abord, effectuons une requête de recherche textuelle, en recherchant des utilisateurs dont les noms d'utilisateur contiennent la valeur de recherche javascript 1 const douserquery = async function () { 2 // this value comes from a state variable 3 const usernamesearchvalue = usernamesearch; 4 // this will create your user query 5 const parsequery = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 if (usernamesearchvalue !== '') { 9 // "contains" will retrieve users whose username contain the searched value, case sensitive 10 parsequery contains('username', usernamesearchvalue); 11 // 12 // or 13 // 14 // for case insensitive string search, use "matches", that will take into account 15 // an regexp for matching, in this case use only "i", which is the regexp modifier 16 // for case insensitive 17 parsequery matches('username', usernamesearchvalue, 'i'); 18 } 19 // only after calling "find" all query conditions will resolve 20 return await parsequery 21 find() 22 then(async (queriedusers => { 23 // set the query results to an state variable to retrieve it on your jsx 24 // be aware that empty or invalid queries return as an empty array 25 setqueryresults(queriedusers); 26 return true; 27 }) 28 catch((error) => { 29 // error can be caused by lack of internet connection, but in most 30 // cases "find" will return as an empty array on "then" 31 alert alert('error!', error message); 32 setqueryresults(\[]); 33 return false; 34 }); 35 };1 const douserquery = async function () promise\<boolean> { 2 // this value comes from a state variable 3 const usernamesearchvalue string = usernamesearch; 4 // this will create your user query 5 const parsequery parse query = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 if (usernamesearchvalue !== '') { 9 // "contains" will retrieve users whose username contain the searched value, case sensitive 10 parsequery contains('username', usernamesearchvalue); 11 // 12 // or 13 // 14 // for case insensitive string search, use "matches", that will take into account 15 // an regexp for matching, in this case use only "i", which is the regexp modifier 16 // for case insensitive 17 parsequery matches('username', usernamesearchvalue, 'i'); 18 } 19 // only after calling "find" all query conditions will resolve 20 return await parsequery 21 find() 22 then(async (queriedusers \[parse user]) => { 23 // set the query results to an state variable to retrieve it on your jsx 24 // be aware that empty or invalid queries return as an empty array 25 setqueryresults(queriedusers); 26 return true; 27 }) 28 catch((error object) => { 29 // error can be caused by lack of internet connection, but in most 30 // cases "find" will return as an empty array on "then" 31 alert alert('error!', error message); 32 setqueryresults(\[]); 33 return false; 34 }); 35 }; notez qu'il existe au moins deux façons différentes de rechercher une chaîne, chacune ayant ses applications et avantages spécifiques dans la plupart des cas, vous voudrez utiliser parse query matches parse query matches pour garantir des résultats insensibles à la casse et éviter un comportement inattendu dans votre code après avoir effectué cette requête, votre liste d'utilisateurs sur votre application devrait afficher quelque chose comme ceci en plus de la recherche de chaînes, vous pouvez également effectuer des requêtes “exactes”, lorsque vous souhaitez récupérer des objets contenant une valeur exacte, tout comme avec des champs booléens l'exemple suivant montrera comment récupérer des utilisateurs qui sont vérifiés par email, via le emailverified emailverified champ javascript 1 const douserquery = async function () { 2 // this value comes from a state variable 3 const showonlyverifiedvalue boolean = showonlyverified; 4 // this will create your user query 5 const parsequery = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 if (showonlyverifiedvalue === true) { 9 // "equalto" will retrieve users whose "emailverified" value is exactly "true" 10 parsequery equalto('emailverified', true); 11 } 12 // only after calling "find" all query conditions will resolve 13 return await parsequery 14 find() 15 then(async (queriedusers) => { 16 // set the query results to an state variable to retrieve it on your jsx 17 // be aware that empty or invalid queries return as an empty array 18 setqueryresults(queriedusers); 19 return true; 20 }) 21 catch((error) => { 22 // error can be caused by lack of internet connection, but in most 23 // cases "find" will return as an empty array on "then" 24 alert alert('error!', error message); 25 setqueryresults(\[]); 26 return false; 27 }); 28 };1 const douserquery = async function () promise\<boolean> { 2 // this value comes from a state variable 3 const showonlyverifiedvalue boolean = showonlyverified; 4 // this will create your user query 5 const parsequery parse query = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 if (showonlyverifiedvalue === true) { 9 // "equalto" will retrieve users whose "emailverified" value is exactly "true" 10 parsequery equalto('emailverified', true); 11 } 12 // only after calling "find" all query conditions will resolve 13 return await parsequery 14 find() 15 then(async (queriedusers \[parse user]) => { 16 // set the query results to an state variable to retrieve it on your jsx 17 // be aware that empty or invalid queries return as an empty array 18 setqueryresults(queriedusers); 19 return true; 20 }) 21 catch((error object) => { 22 // error can be caused by lack of internet connection, but in most 23 // cases "find" will return as an empty array on "then" 24 alert alert('error!', error message); 25 setqueryresults(\[]); 26 return false; 27 }); 28 }; votre application devrait maintenant mettre à jour votre liste d'utilisateurs comme ceci un autre exemple courant serait d'appliquer des ordres à votre requête cela peut être fait de deux manières, soit en utilisant parse query ascending/parse query descending parse query ascending/parse query descending ou parse query addascending/parse query adddescending parse query addascending/parse query adddescending le premier cas remplacera tout autre ordre et sera le seul que la requête prendra, tandis que le second se concaténera avec les ordres existants, rendant plusieurs ordres possibles javascript 1 const douserquery = async function () { 2 // this value comes from a state variable 3 const orderbyvalue = orderby; 4 // this will create your user query 5 const parsequery = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 // for list ordering, you can use "addascending" or "adddescending", passing as parameter 9 // which object field should be the one to order by 10 // note that "usernameasc", "usernamedesc" and so on are made up string values applied to a filter in 11 // our example app, so change it by what is suitable to you 12 if (orderbyvalue === 'usernameasc') { 13 parsequery ascending('username'); 14 // 15 // or 16 // 17 parsequery addascending('username'); 18 } else if (orderbyvalue === 'usernamedesc') { 19 parsequery descending('username'); 20 // 21 // or 22 // 23 parsequery adddescending('username'); 24 } else if (orderbyvalue === 'dateasc') { 25 parsequery ascending('createdat'); 26 // 27 // or 28 // 29 parsequery addascending('createdat'); 30 } else if (orderbyvalue === 'datedesc') { 31 parsequery descending('createdat'); 32 // 33 // or 34 // 35 parsequery adddescending('createdat'); 36 } 37 // only after calling "find" all query conditions will resolve 38 return await parsequery 39 find() 40 then(async (queriedusers) => { 41 // set the query results to an state variable to retrieve it on your jsx 42 // be aware that empty or invalid queries return as an empty array 43 setqueryresults(queriedusers); 44 return true; 45 }) 46 catch((error) => { 47 // error can be caused by lack of internet connection, but in most 48 // cases "find" will return as an empty array on "then" 49 alert alert('error!', error message); 50 setqueryresults(\[]); 51 return false; 52 }); 53 };1 const douserquery = async function () promise\<boolean> { 2 // this value comes from a state variable 3 const orderbyvalue string = orderby; 4 // this will create your user query 5 const parsequery parse query = new parse query(parse user); 6 // several query functions can be set to your parse,query, they will 7 // only resolve when calling "find", for example 8 // for list ordering, you can use "addascending" or "adddescending", passing as parameter 9 // which object field should be the one to order by 10 // note that "usernameasc", "usernamedesc" and so on are made up string values applied to a filter in 11 // our example app, so change it by what is suitable to you 12 if (orderbyvalue === 'usernameasc') { 13 parsequery ascending('username'); 14 // 15 // or 16 // 17 parsequery addascending('username'); 18 } else if (orderbyvalue === 'usernamedesc') { 19 parsequery descending('username'); 20 // 21 // or 22 // 23 parsequery adddescending('username'); 24 } else if (orderbyvalue === 'dateasc') { 25 parsequery ascending('createdat'); 26 // 27 // or 28 // 29 parsequery addascending('createdat'); 30 } else if (orderbyvalue === 'datedesc') { 31 parsequery descending('createdat'); 32 // 33 // or 34 // 35 parsequery adddescending('createdat'); 36 } 37 // only after calling "find" all query conditions will resolve 38 return await parsequery 39 find() 40 then(async (queriedusers \[parse user]) => { 41 // set the query results to an state variable to retrieve it on your jsx 42 // be aware that empty or invalid queries return as an empty array 43 setqueryresults(queriedusers); 44 return true; 45 }) 46 catch((error object) => { 47 // error can be caused by lack of internet connection, but in most 48 // cases "find" will return as an empty array on "then" 49 alert alert('error!', error message); 50 setqueryresults(\[]); 51 return false; 52 }); 53 }; votre application doit maintenant organiser vos requêtes comme ceci n'oubliez pas que toutes les contraintes de requête mentionnées ci dessus peuvent être enchaînées et exécutées dans une seule requête, améliorant l'utilisabilité de votre application pour créer différents filtres et ordonnancements qui fonctionneront ensemble voici le code complet présentant toutes les méthodes de requête utilisées dans ce guide javascript 1 const douserquery = async function () { 2 // this value comes from a state variable 3 const usernamesearchvalue = usernamesearch; 4 const showonlyverifiedvalue = showonlyverified; 5 const orderbyvalue = orderby; 6 // this will create your user query 7 const parsequery = new parse query(parse user); 8 // several query functions can be set to your parse,query, they will 9 // only resolve when calling "find", for example 10 if (usernamesearchvalue !== '') { 11 // "contains" will retrieve users whose username contain the searched value, case sensitive 12 parsequery contains('username', usernamesearchvalue); 13 // 14 // or 15 // 16 // for case insensitive string search, use "matches", that will take into account 17 // an regexp for matching, in this case use only "i", which is the regexp modifier 18 // for case insensitive 19 parsequery matches('username', usernamesearchvalue, 'i'); 20 } 21 if (showonlyverifiedvalue === true) { 22 // "equalto" will retrieve users whose "emailverified" value is exactly "true" 23 parsequery equalto('emailverified', true); 24 } 25 // for list ordering, you can use "addascending" or "adddescending", passing as parameter 26 // which object field should be the one to order by 27 if (orderbyvalue === 'usernameasc') { 28 parsequery ascending('username'); 29 // 30 // or 31 // 32 parsequery addascending('username'); 33 } else if (orderbyvalue === 'usernamedesc') { 34 parsequery descending('username'); 35 // 36 // or 37 // 38 parsequery adddescending('username'); 39 } else if (orderbyvalue === 'dateasc') { 40 parsequery ascending('createdat'); 41 // 42 // or 43 // 44 parsequery addascending('createdat'); 45 } else if (orderbyvalue === 'datedesc') { 46 parsequery descending('createdat'); 47 // 48 // or 49 // 50 parsequery adddescending('createdat'); 51 } 52 // only after calling "find" all query conditions will resolve 53 return await parsequery 54 find() 55 then(async (queriedusers) => { 56 // set the query results to an state variable to retrieve it on your jsx 57 // be aware that empty or invalid queries return as an empty array 58 setqueryresults(queriedusers); 59 return true; 60 }) 61 catch((error) => { 62 // error can be caused by lack of internet connection, but in most 63 // cases "find" will return as an empty array on "then" 64 alert alert('error!', error message); 65 setqueryresults(\[]); 66 return false; 67 }); 68 };1 const douserquery = async function () promise\<boolean> { 2 // this value comes from a state variable 3 const usernamesearchvalue string = usernamesearch; 4 const showonlyverifiedvalue boolean = showonlyverified; 5 const orderbyvalue string = orderby; 6 // this will create your user query 7 const parsequery parse query = new parse query(parse user); 8 // several query functions can be set to your parse,query, they will 9 // only resolve when calling "find", for example 10 if (usernamesearchvalue !== '') { 11 // "contains" will retrieve users whose username contain the searched value, case sensitive 12 parsequery contains('username', usernamesearchvalue); 13 // 14 // or 15 // 16 // for case insensitive string search, use "matches", that will take into account 17 // an regexp for matching, in this case use only "i", which is the regexp modifier 18 // for case insensitive 19 parsequery matches('username', usernamesearchvalue, 'i'); 20 } 21 if (showonlyverifiedvalue === true) { 22 // "equalto" will retrieve users whose "emailverified" value is exactly "true" 23 parsequery equalto('emailverified', true); 24 } 25 // for list ordering, you can use "addascending" or "adddescending", passing as parameter 26 // which object field should be the one to order by 27 if (orderbyvalue === 'usernameasc') { 28 parsequery ascending('username'); 29 // 30 // or 31 // 32 parsequery addascending('username'); 33 } else if (orderbyvalue === 'usernamedesc') { 34 parsequery descending('username'); 35 // 36 // or 37 // 38 parsequery adddescending('username'); 39 } else if (orderbyvalue === 'dateasc') { 40 parsequery ascending('createdat'); 41 // 42 // or 43 // 44 parsequery addascending('createdat'); 45 } else if (orderbyvalue === 'datedesc') { 46 parsequery descending('createdat'); 47 // 48 // or 49 // 50 parsequery adddescending('createdat'); 51 } 52 // only after calling "find" all query conditions will resolve 53 return await parsequery 54 find() 55 then(async (queriedusers \[parse user]) => { 56 // set the query results to an state variable to retrieve it on your jsx 57 // be aware that empty or invalid queries return as an empty array 58 setqueryresults(queriedusers); 59 return true; 60 }) 61 catch((error object) => { 62 // error can be caused by lack of internet connection, but in most 63 // cases "find" will return as an empty array on "then" 64 alert alert('error!', error message); 65 setqueryresults(\[]); 66 return false; 67 }); 68 }; conclusion à la fin de ce guide, vous avez appris comment effectuer des requêtes sur les utilisateurs de parse sur react native dans le prochain guide, nous vous montrerons comment enregistrer et lire des données sur parse