Memahami dan Mengimplementasi Parse.Query di React Native

menanyakan pengguna di parse pada react native pendahuluan beberapa aplikasi react native perlu mengelola pengguna aplikasi anda secara langsung atau setidaknya dapat mencantumkan subset tertentu dari mereka parse memiliki alat kueri yang kuat dan mereka juga dapat digunakan untuk pengguna anda di aplikasi media sosial anda, misalnya dalam panduan ini, anda akan belajar bagaimana menggunakan parse query parse query untuk melakukan kueri pengguna yang realistis di aplikasi react native anda menggunakan parse js sdk prasyarat untuk menyelesaikan tutorial ini, anda akan membutuhkan aplikasi react native yang dibuat dan https //www back4app com/docs/react native/parse sdk/react native sdk tujuan untuk membangun fitur kueri pengguna menggunakan parse untuk aplikasi react native 1 memahami kelas parse query setiap operasi kueri parse menggunakan tipe objek parse query parse query yang akan membantu anda mengambil data spesifik dari database anda di seluruh aplikasi anda sangat penting untuk mengetahui bahwa parse query parse query hanya akan terpecahkan setelah memanggil metode ambil (seperti parse query find parse query find atau parse query get parse query get ), jadi kueri dapat disiapkan dan beberapa modifikator dapat dirangkai sebelum benar benar dipanggil untuk membuat parse query parse query baru, anda perlu melewatkan sebagai parameter subclass parse object parse object yang diinginkan, yang akan berisi hasil kueri anda contoh untuk kasus penggunaan panduan ini ( parse user parse user ) dapat dilihat di bawah 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(); anda dapat membaca lebih lanjut tentang parse query parse query kelas https //parseplatform org/parse sdk js/api/master/parse query html 2 melakukan kueri pengguna yang relevan mari kita lihat beberapa kueri relevan yang mungkin perlu anda lakukan saat mengelola atau menampilkan pengguna di aplikasi anda pertama tama, mari kita lakukan kueri pencarian teks, mencari pengguna yang nama penggunanya mengandung nilai pencarian 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 }; perhatikan bahwa ada setidaknya dua cara berbeda untuk mencari sebuah string, masing masing memiliki aplikasi dan keuntungan spesifiknya dalam banyak kasus, anda akan ingin menggunakan parse query matches parse query matches untuk memastikan hasil yang tidak peka huruf besar/kecil dan menghindari perilaku yang tidak terduga dalam kode anda setelah melakukan kueri ini, daftar pengguna anda di aplikasi anda seharusnya menunjukkan sesuatu seperti ini selain kueri string, anda juga dapat melakukan kueri “tepat”, ketika anda ingin mengambil objek yang mengandung nilai yang tepat, sama seperti dengan bidang boolean contoh berikut akan menunjukkan cara mengambil pengguna yang terverifikasi melalui email, melalui emailverified emailverified bidang 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 }; aplikasi anda sekarang harus memperbarui daftar pengguna anda seperti ini contoh umum lainnya adalah menerapkan urutan pada kueri anda ini dapat dilakukan dengan dua cara, baik dengan menggunakan parse query ascending/parse query descending parse query ascending/parse query descending atau parse query addascending/parse query adddescending parse query addascending/parse query adddescending kasus pertama akan menimpa urutan lainnya dan akan menjadi satu satunya yang akan diambil oleh kueri, sedangkan yang terakhir akan menggabungkan dengan urutan yang ada, sehingga memungkinkan beberapa urutan 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 }; aplikasi anda sekarang harus mengurutkan kueri anda seperti ini ingat bahwa semua batasan kueri yang disebutkan di atas dapat dirangkai dan dilakukan dalam satu kueri, meningkatkan kegunaan aplikasi anda untuk membuat berbagai filter dan pengurutan yang akan bekerja bersama sama berikut adalah kode lengkap yang menyajikan semua metode kueri yang digunakan dalam panduan ini 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 }; kesimpulan di akhir panduan ini, anda telah belajar bagaimana melakukan kueri pada pengguna parse di react native di panduan berikutnya, kami akan menunjukkan kepada anda cara menyimpan dan membaca data di parse