【iOS】FMDB封装，查询自动mapping
sqlite几乎所有的App都会用到，但是系统自带的sqlite API是用C语言写的，非常不友好，用起来非常不便，通常我们使用第三方封装好的工具，例如：FMDB（https://github.com/ccgus/fmdb）
FMDB的提供了一种更简单，方便的API，并且还提供了线程安全的队列FMDatabaseQueue用于数据库的读写，关于FMDB的使用，参见github上的描述
在使用FMDB查询表的时候的时候我们一般用下面方式
1、定义一个数据模型PersonModel
@interface PersonModel : NSObject @property (nonatomic, assign) NSInteger peopleId;
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *gender;
@property (nonatomic, assign) float weight;
@property (nonatomic, assign) double height;
@property (nonatomic, assign) short age;
@property (nonatomic, assign) long score;
@property (nonatomic, strong) NSDate *createTime;
@property (nonatomic, assign) BOOL married;
@property (nonatomic, strong) NSData *desc; @end
2、插入数据
NSString *sql = @"insert into People(name, gender, weight, height, age, score, createTime, married, desc) values(?,?,?,?,?,?,?,?,?)";
NSString *text = @"dataValue";
NSData *data = [text dataUsingEncoding:NSUTF8StringEncoding];
NSArray *param = @[@"bomo", @"male", @, @175l, @, @, [NSDate date], @NO, data];
[_queue inDatabase:^(FMDatabase *db) {
[db executeUpdate:sql withArgumentsInArray:param];
}];
3、查询
NSString *sql = @"select * from People";
__block NSMutableArray *people = [NSMutableArray array];
[_queue inDatabase:^(FMDatabase *db) {
FMResultSet *rs = [db executeQuery:sql];
while ([rs next]) {
person.name = [rs stringForColumn:@"name"];
person.gender = [rs stringForColumn:@"gender"];
person.height = [rs doubleForColumn:@"height"];
person.score = [rs longForColumn:@"score"];
person.createTime = [rs dateForColumn:@"createTime"];
person.married = [rs boolForColumn:@"married"];
person.desc = [rs dataForColumn:@"desc"];
//下面几种方式读取数据会导致数据类型不一致的问题
//person.peopleId = [rs intForColumn:@"peopleId"];
//person.age = [rs intForColumn:@"age"];
//person.weight = [rs doubleForColumn:@"weight"];
[people addObject:person];
}
[rs close];
}];
这里的查询方法需要对每一个属性进行读取和赋值，并且可能有数据类型不一致的问题，比如 读取出来的int 赋值给NSInteger 类型，double类型赋值给float类型，下面我们对查询方法进行改造，让其变得更通用，可以自动映射查询结果到Model，并提供数据库列名到属性名之间的映射
1、定义映射协议
#import <Foundation/Foundation.h> //实现数据库列名到model属性名的映射
@protocol ColumnPropertyMappingDelegate <NSObject> @required
- (NSDictionary *)columnPropertyMapping; @end
2、修改PersonModel模型
#import <Foundation/Foundation.h>
#import "ColumnPropertyMappingDelegate.h" @interface PersonModel : NSObject <ColumnPropertyMappingDelegate> @property (nonatomic, assign) NSInteger peopleId;
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *gender;
@property (nonatomic, assign) float weight;
@property (nonatomic, assign) double height;
@property (nonatomic, assign) short age;
@property (nonatomic, assign) long score;
@property (nonatomic, strong) NSDate *createTime;
@property (nonatomic, assign) BOOL married;
@property (nonatomic, strong) NSData *desc; @end @implementation PersonModel - (NSDictionary *)columnPropertyMapping
{
return @{@"id": @"peopleId",
@"str1": @"name",
@"str2": @"gender",
@"float1": @"weight",
@"double1": @"height",
@"short1": @"age",
@"long1": @"score",
@"date1": @"createTime",
@"bool1": @"married",
@"data1": @"desc"};
} @end
数据库的列名如果与Model的属性名不一致，可以通过改映射函数进行配置
3、查询函数，关键方法
/**
* 执行查询操作，自定构造models集合
*
* @param sql sql语句
* @param args sql参数
* @param modelClass 结果集model类型
* @param block 对model执行自定义操作
*
* @return 查询结果集
*/
- (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block
{
__block NSMutableArray *models = [NSMutableArray array]; [_queue inDatabase:^(FMDatabase *db) {
NSDictionary *mapping = nil; FMResultSet *rs = [db executeQuery:sql withArgumentsInArray:args];
while ([rs next]) {
id model = [[modelClass alloc] init];
if(!mapping && [model conformsToProtocol:@protocol(ColumnPropertyMappingDelegate)]) {
//实现了列-属性转换协议
mapping = [model columnPropertyMapping];
} for (int i = ; i < [rs columnCount]; i++) {
//列名
NSString *columnName = [rs columnNameForIndex:i];
//进行数据库列名到model之间的映射转换，拿到属性名
NSString *propertyName; if(mapping) {
propertyName = mapping[columnName];
if (propertyName == nil) {
//如果映射未定义，则视为相同
propertyName = columnName;
}
} else {
propertyName = columnName;
} objc_property_t objProperty = class_getProperty(modelClass, propertyName.UTF8String);
//如果属性不存在，则不操作
if (objProperty) {
if(![rs columnIndexIsNull:i]) {
[self setProperty:model value:rs columnName:columnName propertyName:propertyName property:objProperty];
}
} NSAssert(![propertyName isEqualToString:@"description"], @"description为自带方法，不能对description进行赋值，请使用其他属性名或请ColumnPropertyMappingDelegate进行映射");
} //执行自定义操作
if (block) {
block(model, rs);
}
[models addObject:model];
} [rs close];
}];
return models;
} /**
* 进行属性赋值
*/
- (void)setProperty:(id)model value:(FMResultSet *)rs columnName:(NSString *)columnName propertyName:(NSString *)propertyName property:(objc_property_t)property
{
// @"f":@"float",
// @"i":@"int",
// @"d":@"double",
// @"l":@"long",
// @"c":@"BOOL",
// @"s":@"short",
// @"q":@"long",
// @"I":@"NSInteger",
// @"Q":@"NSUInteger",
// @"B":@"BOOL", NSString *firstType = [[[[NSString stringWithUTF8String:property_getAttributes(property)] componentsSeparatedByString:@","] firstObject] substringFromIndex:]; if ([firstType isEqualToString:@"f"]) {
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.floatValue) forKey:propertyName]; } else if([firstType isEqualToString:@"i"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.intValue) forKey:propertyName]; } else if([firstType isEqualToString:@"d"]){
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName]; } else if([firstType isEqualToString:@"l"] || [firstType isEqualToString:@"q"]){
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName]; } else if([firstType isEqualToString:@"c"] || [firstType isEqualToString:@"B"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.boolValue) forKey:propertyName]; } else if([firstType isEqualToString:@"s"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.shortValue) forKey:propertyName]; } else if([firstType isEqualToString:@"I"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.integerValue) forKey:propertyName]; } else if([firstType isEqualToString:@"Q"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.unsignedIntegerValue) forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSData\""]){
NSData *value = [rs dataForColumn:columnName];
[model setValue:value forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSDate\""]){
NSDate *value = [rs dateForColumn:columnName];
[model setValue:value forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSString\""]){
NSString *value = [rs stringForColumn:columnName];
[model setValue:value forKey:propertyName]; } else {
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName];
}
}
我们把数据库的查询和更新方法封装成DbService
#import <Foundation/Foundation.h>
@class FMResultSet; @interface DbService : NSObject - (instancetype)initWithPath:(NSString *)path; /**
* 查询第一行第一列的数据
*/
- (id)executeScalar:(NSString *)sql param:(NSArray *)param; /**
* 查询行数
*/
- (NSInteger)rowCount:(NSString *)tableName; /**
* 更新数据
*/
- (BOOL)executeUpdate:(NSString *)sql param:(NSArray *)param; #pragma mark - 查询操作自动构建Model /**
* 执行查询操作，自定构造models集合
*
* @param sql sql语句
* @param args sql参数
* @param modelClass 结果集model类型
*
* @return 查询结果集
*/
- (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass; /**
* 执行查询操作，自定构造models集合
*
* @param sql sql语句
* @param args sql参数
* @param modelClass 结果集model类型
* @param block 对model执行自定义操作
*
* @return 查询结果集
*/ - (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block; /**
* 查询结果集取得model集合
*
* @param rs 数据库查询结果集
* @param modelClass 结果集model类型
*
* @return 查询结果集
*/
- (NSArray *)resultForModels:(FMResultSet *)rs modelClass:(Class)modelClass; /**
* 查询结果集取得model集合
*
* @param rs 数据库查询结果集
* @param modelClass 结果集model类型
* @param block 对model执行自定义操作
*
* @return 查询结果集
*/
- (NSArray *)resultForModels:(FMResultSet *)rs modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block; @end
#import "DbService.h"
#import <objc/runtime.h>
#import "FMDB.h"
#import "ColumnPropertyMappingDelegate.h" #import "PersonModel.h" @interface DbService ()
{
FMDatabaseQueue *_queue;
} @end @implementation DbService - (instancetype)initWithPath:(NSString *)path
{
if (self = [super init]) {
_queue = [FMDatabaseQueue databaseQueueWithPath:path];
} return self;
} - (BOOL)executeUpdate:(NSString *)sql param:(NSArray *)param
{
__block BOOL result = NO;
[_queue inDatabase:^(FMDatabase *db) {
if (param && param.count > ) {
result = [db executeUpdate:sql withArgumentsInArray:param];
} else {
result = [db executeUpdate:sql];
}
}]; return result; } - (id)executeScalar:(NSString *)sql param:(NSArray *)param
{
__block id result; [_queue inDatabase:^(FMDatabase *db) {
FMResultSet *rs = [db executeQuery:sql withArgumentsInArray:param];
if ([rs next]) {
result = rs[];
} else {
result = ;
}
}];
return result;
} - (NSInteger)rowCount:(NSString *)tableName
{
NSNumber *number = (NSNumber *)[self executeScalar:[NSString stringWithFormat:@"SELECT COUNT(*) FROM %@", tableName] param:nil];
return [number longValue];
} #pragma mark -
#pragma mark -- 自动创建model查询方法
- (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass
{
return [self executeQuery:sql withArgumentsInArray:args modelClass:modelClass performBlock:nil];
} - (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block
{
__block NSMutableArray *models = [NSMutableArray array]; [_queue inDatabase:^(FMDatabase *db) {
NSDictionary *mapping = nil; FMResultSet *rs = [db executeQuery:sql withArgumentsInArray:args];
while ([rs next]) {
id model = [[modelClass alloc] init];
if(!mapping && [model conformsToProtocol:@protocol(ColumnPropertyMappingDelegate)]) {
//实现了列-属性转换协议
mapping = [model columnPropertyMapping];
} for (int i = ; i < [rs columnCount]; i++) {
//列名
NSString *columnName = [rs columnNameForIndex:i];
//进行数据库列名到model之间的映射转换，拿到属性名
NSString *propertyName; if(mapping) {
propertyName = mapping[columnName];
if (propertyName == nil) {
//如果映射未定义，则视为相同
propertyName = columnName;
}
} else {
propertyName = columnName;
} objc_property_t objProperty = class_getProperty(modelClass, propertyName.UTF8String);
//如果属性不存在，则不操作
if (objProperty) {
if(![rs columnIndexIsNull:i]) {
[self setProperty:model value:rs columnName:columnName propertyName:propertyName property:objProperty];
}
} NSAssert(![propertyName isEqualToString:@"description"], @"description为自带方法，不能对description进行赋值，请使用其他属性名或请ColumnPropertyMappingDelegate进行映射");
} //执行自定义操作
if (block) {
block(model, rs);
}
[models addObject:model];
} [rs close];
}];
return models;
} /**
* 解析结果集（models）
*/
- (NSArray *)resultForModels:(FMResultSet *)rs modelClass:(Class)modelClass
{
return [self resultForModels:rs modelClass:modelClass performBlock:nil];
} - (NSArray *)resultForModels:(FMResultSet *)rs modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block;
{
NSDictionary *mapping = nil; NSMutableArray *models = [NSMutableArray array];
while ([rs next]) {
id model = [[modelClass alloc] init];
if(!mapping && [model conformsToProtocol:@protocol(ColumnPropertyMappingDelegate)]) {
//实现了列-属性转换协议
mapping = [model columnPropertyMapping];
} for (int i = ; i < [rs columnCount]; i++) {
//列名
NSString *columnName = [rs columnNameForIndex:i];
//进行数据库列名到model之间的映射转换，拿到属性名
NSString *propertyName; if(mapping) {
propertyName = mapping[columnName];
if (propertyName == nil) {
propertyName = columnName;
}
} else {
propertyName = columnName;
} objc_property_t objProperty = class_getProperty(modelClass, propertyName.UTF8String);
//如果属性不存在，则不操作
if (objProperty) {
if(![rs columnIndexIsNull:i]) {
[self setProperty:model value:rs columnName:columnName propertyName:propertyName property:objProperty];
}
} NSAssert(![propertyName isEqualToString:@"description"], @"description为自带方法，不能对description进行赋值，请使用其他属性名或请ColumnPropertyMappingDelegate进行映射");
} //执行自定义操作
if (block) {
block(model, rs);
} [models addObject:model];
}
[rs close]; return models;
} /**
* 进行属性赋值
*/
- (void)setProperty:(id)model value:(FMResultSet *)rs columnName:(NSString *)columnName propertyName:(NSString *)propertyName property:(objc_property_t)property
{
// @"f":@"float",
// @"i":@"int",
// @"d":@"double",
// @"l":@"long",
// @"c":@"BOOL",
// @"s":@"short",
// @"q":@"long",
// @"I":@"NSInteger",
// @"Q":@"NSUInteger",
// @"B":@"BOOL", NSString *firstType = [[[[NSString stringWithUTF8String:property_getAttributes(property)] componentsSeparatedByString:@","] firstObject] substringFromIndex:]; if ([firstType isEqualToString:@"f"]) {
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.floatValue) forKey:propertyName]; } else if([firstType isEqualToString:@"i"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.intValue) forKey:propertyName]; } else if([firstType isEqualToString:@"d"]){
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName]; } else if([firstType isEqualToString:@"l"] || [firstType isEqualToString:@"q"]){
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName]; } else if([firstType isEqualToString:@"c"] || [firstType isEqualToString:@"B"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.boolValue) forKey:propertyName]; } else if([firstType isEqualToString:@"s"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.shortValue) forKey:propertyName]; } else if([firstType isEqualToString:@"I"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.integerValue) forKey:propertyName]; } else if([firstType isEqualToString:@"Q"]){
NSNumber *number = [rs objectForColumnName:columnName];
[model setValue:@(number.unsignedIntegerValue) forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSData\""]){
NSData *value = [rs dataForColumn:columnName];
[model setValue:value forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSDate\""]){
NSDate *value = [rs dateForColumn:columnName];
[model setValue:value forKey:propertyName]; } else if([firstType isEqualToString:@"@\"NSString\""]){
NSString *value = [rs stringForColumn:columnName];
[model setValue:value forKey:propertyName]; } else {
[model setValue:[rs objectForColumnName:columnName] forKey:propertyName];
}
} @end
PersonModel.m
创建一个PeopleService演示一下
#import <Foundation/Foundation.h> @interface PeopleService : NSObject + (instancetype)shareInstance; - (void)createTable; - (void)insertOnePerson; - (NSArray *)query; @end
PeopleService.h
#import "PersonModel.h"
#import "PeopleService.h"
#import "DbService.h" @interface PeopleService ()
{
DbService *_dbService;
} @end @implementation PeopleService + (instancetype)shareInstance
{
static id instance = nil; static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
}); return instance;
} - (instancetype)init
{
if (self = [super init]) {
NSString *dbName = @"people.db";
NSString *directory = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
NSString *dbPath = [directory stringByAppendingPathComponent:dbName];
_dbService = [[DbService alloc] initWithPath:dbPath];
}
return self;
} - (void)createTable
{
NSString *sql = @"CREATE TABLE People ( \
id INTEGER PRIMARY KEY AUTOINCREMENT, \
str1 TEXT, \
str2 TEXT, \
float1 REAL, \
double1 INTEGER, \
short1 REAL, \
long1 REAL, \
date1 TEXT, \
bool1 INTEGER, \
data1 BLOB \
)";
[_dbService executeUpdate:sql param:nil];
} - (void)insertOnePerson
{
NSString *sql = @"insert into People(str1, str2, float1, double1, short1, long1, date1, bool1, data1) values(?,?,?,?,?,?,?,?,?)"; NSString *text = @"dataValue";
NSData *data = [text dataUsingEncoding:NSUTF8StringEncoding]; NSArray *param = @[@"bomo", @"male", @, @175l, @, @, [NSDate date], @NO, data]; [_dbService executeUpdate:sql param:param];
} - (NSArray *)query
{
return [_dbService executeQuery:@"select * from People" withArgumentsInArray:nil modelClass:[PersonModel class]];
} @end
PeopleService.m
测试
[[PeopleService shareInstance] createTable];
[[PeopleService shareInstance] insertOnePerson];
NSArray *people = [[PeopleService shareInstance] query]; for (PersonModel *person in people) {
NSLog(@"name = %@, age = %d", person.name, person.age);
}
我们看一下数据库的表结构
查询操作只需要一行代码，其他的都交给DbService，减少代码量，减少人为错误，由于个人水平有限，如有疏漏或问题，欢迎回复，如果大家有更好的方式，可以一起讨论
Demo：http://files.cnblogs.com/files/bomo/FmdbDemo.zip
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