Add precondition to liquibase changesets

liquibase_precond_gen.py

# pip install beautifulsoup4 lxml
# - Can handle createTable, addUniqueConstraint, and addForeignKeyConstraint
# - Every command has to be wrapped in an own changeset to be found by the script

from bs4 import BeautifulSoup

file = open("data.txt", "r")
xml = BeautifulSoup(file, 'xml')

changesets = xml.find_all('changeSet')

for changeset in changesets:
    createTable = changeset.find_all('createTable')
    addUniqueConstraint = changeset.find_all('addUniqueConstraint')
    addForeignKeyConstraint = changeset.find_all('addForeignKeyConstraint')

    if (len(createTable) > 0):
        precondition = xml.new_tag("preConditions", onFail="MARK_RAN")
        nott = xml.new_tag("not")
        tableExists = xml.new_tag("tableExists", schemaName=createTable[0]['schemaName'], tableName=createTable[0]['tableName'])
        nott.append(tableExists)
        precondition.append(nott)
        changeset.insert(0, precondition)

    if (len(addUniqueConstraint) > 0):
        precondition = xml.new_tag("preConditions", onFail="MARK_RAN")
        nott = xml.new_tag("not")
        tableExists = xml.new_tag("uniqueConstraintExists", constraintName=addUniqueConstraint[0]['constraintName'], tableName=addUniqueConstraint[0]['tableName'])
        nott.append(tableExists)
        precondition.append(nott)
        changeset.insert(0, precondition)

    if (len(addForeignKeyConstraint) > 0):
        precondition = xml.new_tag("preConditions", onFail="MARK_RAN")
        nott = xml.new_tag("not")
        tableExists = xml.new_tag("foreignKeyConstraintExists",
                                  foreignKeyName=addForeignKeyConstraint[0]['constraintName'],
                                  foreignKeyTableName=addForeignKeyConstraint[0]['baseTableName'],
                                  schemaName=addForeignKeyConstraint[0]['referencedTableSchemaName'])
        nott.append(tableExists)
        precondition.append(nott)
        changeset.insert(0, precondition)

f = open("done.xml", "w")
f.write(xml.prettify())
f.close()