Support default value.

[shellmanme]

Support default value. (i.e. "uuid()", "uuid_short()", etc).

[GeertJohan]

Please add test cases and re-open this PR on master branch (we've deprecated the develop branch)

[GeertJohan]

@zallwu If you could add a testcase and docs, as well as rebase to master, then we could merge this at v2-phase1 (see #270). Otherwise we'll have to postphone it to v2.1, at which point the codebase will have changed a lot.

[GeertJohan]

Looked at the code again. I think it would be better to add default as a part of the db tag:
db:"name, default:uuid()"

[GeertJohan]

I'll merge and add open an issue so we can work it out in phase3.

[GeertJohan]

Merged at 96583e8

[GeertJohan]

Actually added the default option to the db tag just now..

[wzzhu]

This is not completed. Should add the patch below:

--- a/table.go
+++ b/table.go
@@ -211,6 +211,9 @@ func (t *TableMap) SqlForCreate(ifNotExists bool) string {
if col.Unique {
s.WriteString(" unique")
}

•                   if col.DefaultValue != "" {
  

•                           s.WriteString(fmt.Sprintf(" default %s", col.DefaultValue))
  

•                   }
                  if col.isAutoIncr {
                          s.WriteString(fmt.Sprintf(" %s", dialect.AutoIncrStr()))
                  }