Default to TEXT. Dropping using VARCHAR

[shenghu]

Description

When defining property in model using 'String' or 'JSON', current code uses VARCHAR as datatype. However cassandra always uses TEXT to define the column. E.g. create table "test" ( id uuid primary key, value VARCHAR); generates table

cqlsh:test> desc table "test";

CREATE TABLE test.test (
    id uuid PRIMARY KEY,
    value text
) WITH bloom_filter_fp_chance = 0.01
...

Thus, when doing autoupdate, loopback-connector-cassandra always thinks there is schema change as the datatype is VARCHAR from model definition while it is TEXT from database.

In Cassandra, varchar is a synonym for text. From https://datastax-oss.atlassian.net/browse/JAVA-402, I think loopback-connector-cassandra should drop using VARCHAR to avoid unnecessary issue like migration.

Also Cassandra dropping support to alter column type today.

Related issues

Checklist

• [x] New tests added or existing tests modified to cover all changes
• [x] Code conforms with the style guide

[shenghu]

@jannyHou can you review this PR? Thanks.

[shenghu]

Closed as it is included in PR #59