Rails: How to handle “Attribute was supposed to be a Array, but was a String” error?

问题:

I have a table with one column that is of text type. There's a small string in it that should be serialized as an array

serialize :image_urls, Array  

There are times when SQL is just faster for inserting data. When this is the case, I do the insert as a string

["image1.jpg", "image2.jpg"] 

Since I'm inserting a string my Rails app crashes when it tries to read the data, with the following error message:

Attribute was supposed to be a Array, but was a String 

Is there a way to not have this error thrown, or to catch it and convert the data?

I mean converting the string to an array is just a simple call, so, this should be easy. I just don't know where, or how to accomplish it.

---

I sort of think overriding object_from_yaml, but I'm not sure where to do this work.
Am I in the right track?

回答1:

From the fine manual:

serialize(attr_name, class_name = Object)
[...] The serialization is done through YAML.

So the column should contain a YAMLized version of your image_urls but '["image1.jpg", "image2.jpg"]' is not a YAML array. If you want to muck around with the raw serialized data then you should use something like

["image1.jpg", "image2.jpg"].to_yaml # ---------------------------^^^^^^^ 

to generate the string.

Or better, stop using serialize altogether in favor of a separate table.

回答2:

In Rails 4 it worked for me without any .to_yaml, just added it to strong params as image_urls: []

回答3:

you can try like this: {:serialized_attribute_name => [ ]}. And don't forget to add this in appropriate controller as strong parameters. It helps me when I was suffering from same problem.

文章来源: Rails: How to handle “Attribute was supposed to be a Array, but was a String” error?