How to save & retrieve NSdata into sqlite through

问题:

How can I save NSData into sqlite, I am using FMDB wrapper for saving data.

Below is the code which I have tried so far
For saving

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:model.expertArray];; 
NSString *query = [NSString stringWithFormat:@"insert into save_article values ('%@','%@','%@','%@','%@','%@')",
                       model.Id, model.title, model.earliestKnownDate, data, model.excerpt,model.image_url];

For Retriving

while([results next]) {
  NSData *data = [results dataForColumn:@"experts"];
        NSMutableArray *photoArray = [NSKeyedUnarchiver unarchiveObjectWithData:data];
 }     

I have tried both datatype blob & text but no luck so far, can anybody guide me how to do it?

回答1:

Below is the Snippet for all who may face the same issue while inserting NSData to Sqlite using FMDB.

In my Case I wanted to store NSArray in Sqlite So i first convert the NSArray into NSData & then store it in Sqlite.

Converting NSArray into NSData

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:YourNSarray];;

Saving NSData into Sqlite

[database executeQuery:@"insert into save_article values (?,?,?,?,?,?)", model.Id, model.title, model.earliestKnownDate, data, model.excerpt,model.image_url];

Note:- Don't build a query using stringWithFormat[below is the code which you should not use]:. Thanks to @rmaddy & @hotlicks for pointing me to this :)

NSString *query = [NSString stringWithFormat:@"insert into user values ('%@', %d)",
@"brandontreb", 25];
[database executeUpdate:query];

and now the last step i.e retrieving NSData back to NSArray

NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:[database dataForColumn:@"yourcololumname"]];

Hope this will help the needy & beginner :)

回答2:

Don't build a query using stringWithFormat:. This is a bad idea for several reasons.

Use the executeQuery method where you put a ? for each value to be bound to the query.

Something like this:

[database executeQuery:@"insert into save_article values (?,?,?,?,?,?)", model.Id, model.title, model.earliestKnownDate, data, model.excerpt,model.image_url];