# Compare schemas
{% hint style="success" %}
This is the official documentation of the `@forestadmin/agent` Node.js agent.
{% endhint %}
## Checklist
### Checking that the agents are compatible
Making an agent which works is not enough: you also need to make sure that it generates a schema where the naming of most entities is the same as the old one.
This is because all the UI / and security customizations that you have made are identified by the name of the entity to which they are applied.
This is valid for:
* Charts (in dashboards and the collection view)
* Order and visibility of fields in table-view, detail-form, related data, segments
* Roles and Scopes
* Segments visibility
* Summary views and Workspaces
#### Example
For instance, if you created a chart on the `customers` collection that displays the TOP 10 customers by number of orders, you will need to make sure that:
* The `customers` collection still exists and has the same name
* The `orders` collection still exists and has the same name
* The `customers` collection still has a relationship called `orders`
#### Checking the compatibility with `.forestadmin-schema.json`, `jq` and `diff`
{% hint style="info" %}
* `jq` is a command line tool that allows you to manipulate JSON files. If you don't have it installed, you can install it with [one of the following methods](https://stedolan.github.io/jq/download/) or [use it online](https://jqplay.org/).
* `diff` is a command line tool that allows you to compare two files. It is installed by default on virtually all Unix systems, windows users can use [online versions](https://www.diffchecker.com/).
{% endhint %}
To ensure agents are compatible, we have a tool at our disposal: [the `.forestadmin-schema.json` file](https://docs.forestadmin.com/developer-guide-agents-nodejs/under-the-hood/forestadmin-schema).
However, diffing two `.forestadmin-schema.json` files is *extremely* tedious: the file contains a lot of information that is not relevant to our objective.
Instead, we can choose to focus on the differences that matter the most: the name of the different entities.
**Extracting the list of entities**
Extracting the list of entities exported by an agent can be done with the following `jq` command.
Run this command in the directory of both your old and new agent: it will generate a file called `agent-entities.txt` in the current directory.
```console
$ jq -r '.collections[] | (
"Collection: \"\(.name)\"",
"Action: \"\(.name)\" has \"\(.actions[].name)\"",
"Field: \"\(.name)\" has \"\(.fields[] | select(.reference == null) | .field)\"",
"Relationship: \"\(.name)\" has \"\(.fields[] | select(.reference) | .field)\"",
"Segment: \"\(.name)\" has \"\(.segments[].name)\""
)' .forestadmin-schema.json | sort > agent-entities.txt
```
Equivalent Node.js script
You can also execute the following script to generate the same file:
```javascript
const fs = require('fs');
const forestAdminSchema = require('./.forestadmin-schema.json');
const entities = forestAdminSchema.collections
.map(collection => [
`Collection: "${collection.name}"`,
...collection.actions.map(
action => `Action: "${collection.name}" has "${action.name}"`,
),
...collection.fields
.filter(field => !field.reference)
.map(field => `Field: "${collection.name}" has "${field.field}"`),
...collection.fields
.filter(field => field.reference)
.map(field => `Relationship: "${collection.name}" has "${field.field}"`),
...collection.segments.map(
segment => `Segment: "${collection.name}" has "${segment.name}"`,
),
])
.flat()
.sort();
fs.writeFileSync('agent-entities.txt', entities.join('\n'));
```
**Comparing the list of entities**
Once you have generated the `agent-entities.txt` file for both your old and new agent, you can diff them with the following command:
```console
$ diff --side-by-side --suppress-common-lines --minimal [old-agent-folder]/agent-entities.txt [new-agent-folder]/agent-entities.txt
Collection: "account" <
Field: "account" has "_id" <
Field: "account" has "firstname" <
Field: "account" has "lastname" <
Field: "account_address" has "_id" <
Field: "account_address" has "country" | Field: "account_address" has "Country"
Relationship: "account" has "address" <
Relationship: "account" has "bills" <
Relationship: "account" has "store" <
```
Diff files are read using the following format:
* `>`: line is present in the new file, but not in the old one
* `<`: line is present in the old file, but not in the new one
* '|': line is present in both files, but the content is different
#### Fixing differences
Once you have identified the differences, you can fix them by:
| Danger level | Difference | Fix |
| ------------ | ----------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 🔴 | Collections or fields have different names (i.e. `camelCase` vs `snake_case`) | Rename the collections in the new agent ([docs](https://docs.forestadmin.com/developer-guide-agents-nodejs/data-sources/getting-started/naming-conflicts)) |
| 🔴 | Missing Smart features (actions, fields, relationships, segments, ...) | Port the missing smart features to your new agent |
| 🟢 | Extra collections | You can remove them ([docs](https://docs.forestadmin.com/developer-guide-agents-nodejs/data-sources/getting-started/partial-imports)) |
| 🟢 | Extra fields | You can remove them ([docs](https://docs.forestadmin.com/developer-guide-agents-nodejs/agent-customization/fields/import-rename-remove#renaming-and-removing-fields)) |
---
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If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
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```
GET https://docs.forestadmin.com/developer-guide-agents-nodejs/getting-started/migrating/steps/compare.md?ask=
```
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The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.