# Creating index mappings with nested fields
**URL:** https://discuss.elastic.co/t/creating-index-mappings-with-nested-fields/133224
**Category:** Elasticsearch
**Created:** [May 24, 2018, 8:54pm UTC](https://discuss.elastic.co/t/creating-index-mappings-with-nested-fields/133224 "2018-05-24T20:54:58Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@mehdi-gital](https://discuss.elastic.co/u/mehdi-gital)
#### Post date: [May 24, 2018, 8:54pm UTC](https://discuss.elastic.co/t/creating-index-mappings-with-nested-fields/133224/1 "2018-05-24T20:54:58Z")
```
Hey guys,
```
I've been using Elastic for about two weeks and today I ran into some issues that don't make sense.
I'm going to ask multiple questions to build up toward my main question. Warning: long question!
I write my queries in Kibana under Elastic 5. Questions:
1. What's the deal with underscore? I believe in the OOP context, underscore indicates that the method is internal. What does it mean in a key in a JSON object? This is copied from the documentation.
Query:
```
PUT my_index
{
"mappings": {
"_doc": {
"properties": {
"user": {
"type": "nested"
}
}
}
}
}
```
Response:
```
{
"error": {
"root_cause": [
{
"type": "invalid_type_name_exception",
"reason": "mapping type name [_doc] can't start with '_'"
}
],
"type": "invalid_type_name_exception",
"reason": "mapping type name [_doc] can't start with '_'"
},
"status": 400
}
```
1. Tried without underscore and it worked. 🙂
Query:
```
PUT my_index
{
"mappings": {
"doc": {
"properties": {
"data": {
"type": "nested"
}
}
}
}
}
```
1. Gave it some data:
Query:
```
PUT my_index/doc/1
{
"group" : "doc",
"data" : [
{
"first" : "John",
"last" : "Smith",
"rating": 2,
"limit": 3
},
{
"first" : "Alice",
"last" : "White",
"rating": 3,
"limit": 3
}
]
}
PUT my_index/doc/2
{
"group" : "doc",
"data" : [
{
"first" : "Average",
"last" : "Joe",
"rating": 3,
"limit": 3
},
{
"first" : "Mr",
"last" : "Champ",
"rating": 5,
"limit": 3
}
]
}
```
Now, time to give it a real query:
```
Get my_index/doc/_search
{
"query": {
"nested": {
"path": "data",
"query": {
"bool": {
"must": [
{
"wildcard": {
"data.first": {
"value": "Aaaaaaa?"
}
}
},
{
"range": {
"vs.rating": {
"gt": 5
}
}
}
]
}
}
}
}
}
```
Response:
```
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 1,
"hits": [
{
"_index": "my_index",
"_type": "doc",
"_id": "2",
"_score": 1,
"_source": {
"group": "doc",
"data": [
{
"first": "Average",
"last": "Joe",
"rating": 3,
"limit": 3
},
{
"first": "Mr",
"last": "Champ",
"rating": 5,
"limit": 3
}
]
}
},
{
"_index": "my_index",
"_type": "doc",
"_id": "1",
"_score": 1,
"_source": {
"group": "doc",
"data": [
{
"first": "John",
"last": "Smith",
"rating": 2,
"limit": 3
},
{
"first": "Alice",
"last": "White",
"rating": 3,
"limit": 3
}
]
}
}
]
}
}
```
I don't understand why it returns everything when it should, in fact, return nothing.
1. My real question is:
What's the syntax for defining the fields that go inside my data field?
Here:
```
"data": {
"type": "nested"
}
```
I was thinking something like this but it won't work:
```
"data": {
"type": "nested",
"properties": {
"first": "text",
"last": "text",
"gender": "text,
"rating": "integer",
"limit": "integer"
}
}
```
Sorry for the super long question but most of the above is contrived code. What I really want in my work is to run a query as follows:
```
{
"query": {
"nested": {
"path": "data",
"query": {
"bool": {
"must": [
{
"wildcard": { "data.first": "A?"}
},
{
"range": {
"data.value": {
"gt": "data.limit"
}
}
}
]
}
}
}
},
"_source": ["data.first", "data.last", "data.value"]
}
```
Please note, I have no issues do that when giving it as a constant. Eg:
"gt": 3
However, I can't seem to reach "data.limit" to put on the right-hand side of "gt".
If you read this far, I truly appreciate that.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [June 21, 2018, 8:55pm UTC](https://discuss.elastic.co/t/creating-index-mappings-with-nested-fields/133224/2 "2018-06-21T20:55:00Z")
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