Updates - The DataJoint Book

Updating existing rows¶

In DataJoint, the principal way of replacing data is by delete and insert. This approach observes referential integrity constraints.

In some cases, it becomes necessary to deliberately correct existing values. The update1 method accomplishes this. The method should only be used to fix problems, and not as part of a regular workflow. When updating an entry, make sure that any information stored in dependent tables that depends on the update values is properly updated as well.

Syntax:

table.update1(record)

Here record is a dict specifying the primary key values for identifying what record to update and the values that should be updated. The entry must already exist.

Example¶

Let’s create the Student table and populate a few entries.

import datajoint as dj
schema = dj.schema('test_update')

@schema
class Student(dj.Manual):
    definition = """
    student_id : int
    ---
    full_name : varchar(100)   # last_name, first_name middle_name
    phone="": varchar(20)
    sex : enum('female', 'male')
    """

Student.insert1(dict(student_id=303, full_name="Rosen, Rose", sex="female"))
Student.insert1(dict(student_id=304, full_name="Rosen, Rose", sex="male", phone="(813)555-3744"))

Student()

We can now update some values. Note that you must specify the primary key and the entry must already exist.

Student.update1(dict(student_id=303, phone="(813)555-7133"))
Student.update1(dict(student_id=304, full_name="Ramesh, Henry"))
Student()

If the entry does not exist or if the primary key value is not specified, update1 raises errors:

Student.update1(dict(student_id=305, phone="(800)555-3377"))

---------------------------------------------------------------------------
DataJointError                            Traceback (most recent call last)
<ipython-input-6-c3ba2ed335d9> in <module>
----> 1 Student.update1(dict(student_id=305, phone="(800)555-3377"))

~/dev/datajoint-python/datajoint/table.py in update1(self, row)
    237         key = {k: row[k] for k in self.primary_key}
    238         if len(self & key) != 1:
--> 239             raise DataJointError('Update entry must exist.')
    240         # UPDATE query
    241         row = [self.__make_placeholder(k, v) for k, v in row.items() if k not in self.primary_key]

DataJointError: Update entry must exist.

Student.update1(dict(phone="(800)555-3377"))

---------------------------------------------------------------------------
DataJointError                            Traceback (most recent call last)
<ipython-input-7-780ca578d6bf> in <module>
----> 1 Student.update1(dict(phone="(800)555-3377"))

~/dev/datajoint-python/datajoint/table.py in update1(self, row)
    228             raise DataJointError('The argument of update1 must be dict-like.')
    229         if not set(row).issuperset(self.primary_key):
--> 230             raise DataJointError('The argument of update1 must supply all primary key values.')
    231         try:
    232             raise DataJointError('Attribute `%s` not found.' % next(k for k in row if k not in self.heading.names))

DataJointError: The argument of update1 must supply all primary key values.