$ cat init/init.js
db.createCollection('tblstest');
db.tblstest.insertMany(
  [
    { name: 'test1', age: 1 },
    { name: 'test2', age: 2 },
    { name: 'test3', age: 3 },
    { name: 'test4', age: 4 },
    { name: 'test5', age: null },
    { name: 'test6', age: null },
    { name: 'test7', age: null },
    { name: 'test8', age: null },
    { name: 'test9', age: 9 },
    { name: 'test10', age: 10 },
  ]
)

$ docker run --rm -it -p 27017:27017 -v $PWD/init:/docker-entrypoint-initdb.d mongo:7.0.3

$ cat .tbls.yml
dsn: mongodb://localhost:27017/test?sampleSize=10
docPath: ./docs/schemas/mongodb
er:
  skip: true

# Repeat multiple times...
$ tbls doc --rm-dist
...

$ git diff
diff --git a/docs/schemas/mongodb/test.tblstest.md b/docs/schemas/mongodb/test.tblstest.md
index d5987f7..881552b 100644
--- a/docs/schemas/mongodb/test.tblstest.md
+++ b/docs/schemas/mongodb/test.tblstest.md
@@ -9,7 +9,7 @@ Count of documents is 10
 | Name | Type | Default | Nullable | Occurrences | Percents | Children | Parents | Comment |
 | ---- | ---- | ------- | -------- | ----------- | -------- | -------- | ------- | ------- |
 | _id | objectId |  | false | 5 | 100.0 |  |  |  |
-| age | int32 |  | false | 5 | 100.0 |  |  |  |
+| age | <nil> |  | false | 5 | 100.0 |  |  |  |
 | name | string |  | false | 5 | 100.0 |  |  |  |

$ cat .tbls.yml
dsn: mongodb://localhost:27019/test?sampleSize=10&multipleFieldType=true
docPath: ./docs/schemas/mongodb
er:
  skip: true

$ tbls doc --rm-dist
$ git diff
diff --git a/docs/schemas/mongodb/test.tblstest.md b/docs/schemas/mongodb/test.tblstest.md
index d5987f7..9e30dda 100644
--- a/docs/schemas/mongodb/test.tblstest.md
+++ b/docs/schemas/mongodb/test.tblstest.md
@@ -8,9 +8,9 @@ Count of documents is 10

 | Name | Type | Default | Nullable | Occurrences | Percents | Children | Parents | Comment |
 | ---- | ---- | ------- | -------- | ----------- | -------- | -------- | ------- | ------- |
-| _id | objectId |  | false | 5 | 100.0 |  |  |  |
-| age | int32 |  | false | 5 | 100.0 |  |  |  |
-| name | string |  | false | 5 | 100.0 |  |  |  |
+| _id | objectId |  | false | 10 | 100.0 |  |  |  |
+| age | <nil>,int32 |  | false | 10 | 100.0 |  |  |  | # 👈 
+| name | string |  | false | 10 | 100.0 |  |  |  |