How do Django Fixtures handle ManyToManyFields?

Question

I'm trying to load in around 30k xml files from clinicaltrials.gov into a mySQL database, and the way I am handling multiple locations, keywords, etc. are in a separate model using ManyToManyFields.

The best way I've figured out is to read the data in using a fixture. So my question is, how do I handle the fields where the data is a pointer to another model?

I unfortunately don't know enough about how ManyToMany/ForeignKeys work, to be able to answer...

Thanks for the help, sample code below: __ represent the ManyToMany fields

{
    "pk": trial_id,
    "model": trials.trial,
    "fields": {
            "trial_id": trial_id,
            "brief_title": brief_title,
            "official_title": official_title,
            "brief_summary": brief_summary,
            "detailed_Description": detailed_description,
            "overall_status": overall_status,
            "phase": phase,
            "enrollment": enrollment,
            "study_type": study_type,
            "condition": _______________,
            "elligibility": elligibility,
            "Criteria": ______________,
            "overall_contact": _______________,
            "location": ___________,
            "lastchanged_date": lastchanged_date,
            "firstreceived_date": firstreceived_date,
            "keyword": __________,
            "condition_mesh": condition_mesh,
    }

}

I do not remember the answer, but if you run your development server, create sample data using admin, and then dump the database in to a json file using "manage.py dumpdata" command, you will be able to create your fixtures using the file as an example. that is what I did when I needed to find out how to create fixtures for relationship fields. :) — akonsu, Oct 05 '11 at 04:31

score 38 · Accepted Answer · edited Sep 10 '14 at 17:31

A foreign key is simple the pk of the object you are linking to, a manytomanyfield uses a list of pk's. so

[
    {
        "pk":1,
        "model":farm.fruit,
        "fields":{
            "name" : "Apple",
            "color" : "Green",
        }
    },
    {
        "pk":2,
        "model":farm.fruit,
        "fields":{
            "name" : "Orange",
            "color" : "Orange",
        }
    },
    {
         "pk":3,
         "model":person.farmer,
         "fields":{
             "name":"Bill",
             "favorite":1,
             "likes":[1,2],
         }
    }
]

You will need to probably write a conversion script to get this done. Fixtures can be very flimsy; it's difficult to get the working so experiment with a subset before you spend a lot of time converting the 30k records (only to find they might not import)

Thanks. Given the flimsiness of fixtures, would you recommend another way of importing XML data into the DB? — CMaury, Oct 05 '11 at 18:40
Use a Python script that reads the XML, and creates an Trial object, then just use trial.save(). — blaze, Feb 06 '14 at 03:30

How do Django Fixtures handle ManyToManyFields?

1 Answers1