how to use the function serialize()?

Mushroom

I was told that the function would serialize data,but I dont know how to use it.

And how to cache data?

Are there any classes to use?

Valkrin

To serialize a variable or mixed variable just do the following:

serialize($anyvar_or_object);

To use the data in the serialized variable or object just use:

unserialize($anyvar_or_object);

Note: In php 3.x using serialize on objects will cause them to lose their methods, but in 4.x they will retain them. Excellent documentation can be found here: http://www.php.net/manual/en/function.serialize.php
Enjoy.

Mushroom

Thanks a lot.

I was a bit confused.But What's "serialize" mean ?And in what condition We often use it ?What's the benifit?

Thank you !

Valkrin

To my knowledge serialize is used when one wants to save an array of data, or mixed variables into one field in a database. What serialize does is, it turns the variable it is given into a string of bytes. Now this string can be stored in the database in one field. For example if you wanted to store someone's phone numbers, all in one field and you were reading them from an array you could serialize the array, toss it in the database and then when you want that array of numbers back you pull the data from the database and unserialize and ta da, you have your array of numbers. One should take precautions when storing serialized data in a database because it might have quotes in it.

Mushroom

I'v got what you have said. Using "implode" and "eplode" is also the same,and can do that work.Am I right?

Valkrin

I suppose so. But implode and explode only work with arrays while serialize works with objects. I'm not too sure about the purpose of serialize either, there might be other uses for it but that is all I could think of, and I might be wrong, 🙁

Mushroom

Thanks!
I am reading the code of a forum.It put the serialized data into database such as the number of the total threads,the number of the total members etc. But updating those data is also a problem.It seems that its not so good because of updating data.How do you think about it?Do you ever met that kind of code?(Sorry,my English is rather pool.)🙁

[deleted]

"But updating those data is also a problem."

That is a very good point. You never put more than one piece of information in one field of a database.

If you want to store more than one phonenumber, make a new 'phonenumbers' table.

Not only is it difficult to update a 'serialized' field, you cannot really use it inside query at all.

For ex: if you want to select all users who have phonenumber=555, you will have to do something like "WHERE phonenumbers LIKE '%555%'" and that can be very slow.

Valkrin

I wish I could help you, but I just learned about serialize about a day ago. I suppose if you were to update the data, you would have to first unserialize it make any changes you needed to make to it and then serialize it again and store it back in the database. I'm not to sure about this. Hopefully someone more knowledegable will come along and help you solve your problem. Good luck.

Mushroom

If you want to store more than one phonenumber, make a new 'phonenumbers' table.

Not only is it difficult to update a 'serialized' field, you cannot really use it inside query at all.

I am afraid you havent understood whatI have said.
Of course you can never search something in a serialized string.
I mean if I store serialized data to cache them,and it will change,you should unserialize them ,change them and serialize them again,so it's not a effient method.

Are there any more effient way to cache data?