sqlite - Best practices for exposing multiple tables using content providers in Android -

-

i'm building app have table events , table venues. want able grant other applications access data. have few questions related best practices kind of problem.

  1. how should structure database classes? have classes eventsdbadapter , venuesdbadapter, provide logic querying each table, while having separate dbmanager (extends sqliteopenhelper) managing database versions, creating/upgrading databases, giving access database (getwriteable/readeabledatabase). recommended solution, or better off either consolidating 1 class (ie. dbmanager) or separation , letting each adapter extends sqliteopenhelper?

  2. how should design content providers multiple tables? extending previous question, should use 1 content provider whole app, or should create separate providers events , venues?

most examples find deal single table apps, appreciate pointers here.

it's bit late you, others may find useful.

first need create multiple content_uris

public static final uri content_uri1 =      uri.parse("content://"+ provider_name + "/sampleuri1"); public static final uri content_uri2 =      uri.parse("content://"+ provider_name + "/sampleuri2");

then expand uri matcher

private static final urimatcher urimatcher; static {     urimatcher = new urimatcher(urimatcher.no_match);     urimatcher.adduri(provider_name, "sampleuri1", sample1);     urimatcher.adduri(provider_name, "sampleuri1/#", sample1_id);           urimatcher.adduri(provider_name, "sampleuri2", sample2);     urimatcher.adduri(provider_name, "sampleuri2/#", sample2_id);       }

then create tables

private static final string database_name = "sample.db"; private static final string database_table1 = "sample1"; private static final string database_table2 = "sample2"; private static final int database_version = 1; private static final string database_create1 =     "create table if not exists " + database_table1 +      " (" + _id1 + " integer primary key autoincrement," +      "data text, stuff text);"; private static final string database_create2 =     "create table if not exists " + database_table2 +      " (" + _id2 + " integer primary key autoincrement," +      "data text, stuff text);";

don't forget add second database_create oncreate()

you going use switch-case block determine table used. insert code

@override public uri insert(uri uri, contentvalues values) {     uri _uri = null;     switch (urimatcher.match(uri)){     case sample1:         long _id1 = db.insert(database_table1, "", values);         //---if added successfully---         if (_id1 > 0) {             _uri = contenturis.withappendedid(content_uri1, _id1);             getcontext().getcontentresolver().notifychange(_uri, null);             }         break;     case sample2:         long _id2 = db.insert(database_table2, "", values);         //---if added successfully---         if (_id2 > 0) {             _uri = contenturis.withappendedid(content_uri2, _id2);             getcontext().getcontentresolver().notifychange(_uri, null);             }         break;     default: throw new sqlexception("failed insert row " + uri);     }     return _uri;                 }

you need devide delete, update, gettype, etc. wherever provider calls database_table or content_uri add case , have database_table1 or content_uri1 in 1 , #2 in next , on many want.


Comments

Post a Comment

Popular posts from this blog

C#: Application without a window or taskbar item (background app) that can still use Console.WriteLine() -

-
i'm trying create application adheres following: no taskbar no console or form window can utilize console.writeline() . (i.e. if executes app command prompt write console.) the problem if create windows form (or wpf) application can have there no taskbar, console or window show up, console.writeline() nothing. if create console app, writes console, can't figure out how hide (and if did hide it, write command prompt window?)... how do this? just create standard console application. callers responsibility hide window caused program (from how run c# console application console hidden ): system.diagnostics.processstartinfo start = new system.diagnostics.processstartinfo(); start.filename = dir + @"\myprocesstostart.exe"; start.windowstyle = system.diagnostics.processwindowstyle.hidden;
Read more

c++ - Convert big endian to little endian when reading from a binary file -

-
this question has answer here: how convert between big-endian , little-endian values in c++? 28 answers i've been looking around how convert big-endian little-endians. didn't find solve problem. seem there's many way can conversion. anyway following code works ok in big-endian system. how should write conversion function work on little-endian system well? this homework, since systems @ school running big-endian system. it's got curious , wanted make work on home computer also #include <iostream> #include <fstream> using namespace std; int main() { ifstream file; file.open("file.bin", ios::in | ios::binary); if(!file) cerr << "not able read" << endl; else { cout << "opened" << endl; int i_var; double d_var; while(!file.eof()) {...
Read more

openssl - Load PKCS#8 binary key into Ruby -

-
i'm trying load particular private key encoded in binary der format ( pkcs#8 ) ruby. however, openssl::pkey won't recognize it. can make work doing console work , transforming pem so: openssl pkcs8 -inform der -in file.key -passin pass:xxxxxxxx >private_key.pem after this, key can correctly read. however, since whole process done in memory instead of writing , reading files. so question is: possible load private keys binary encoded der format ruby/openssl? thank time, fernando yes, can indirectly load pkcs#8 der-encoded private keys using ruby openssl. openssl::pkey::rsa.new handle pem-formatted pkcs#8, easy read binary der , convert pem-formatted string , load string. for example, these der-encoded private keys: $ openssl genrsa | openssl pkcs8 -topk8 -outform der \ -nocrypt -out pkcs8.key $ openssl genrsa | openssl pkcs8 -topk8 -outform der \ -v2 des3 -passout pass:secret -out pkcs8_des3.key you can this: require 'open...
Read more