DiceDB#1022 Command Migration: ('HEXISTS', 'HKEYS', 'HVALS') (DiceDB#…

…1087)

docs/hexists_command_docs.md

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+---
+title: HEXISTS
+description: The `HEXISTS` command in DiceDB checks if a specified field exists within a hash stored at a given key. This command is used to verify the presence of a field within hash data structures, making it essential for conditional logic.
+---
+
+The `HEXISTS` command in DiceDB checks if a specified field exists within a hash stored at a given key. This command is used to verify the presence of a field within hash data structures, making it essential for conditional logic.
+
+## Syntax
+
+```bash
+HEXISTS key field
+```
+
+## Parameters
+
+| Parameter | Description                        | Type   | Required |
+|-----------|------------------------------------|--------|----------|
+| `key`     | The name of the key holding a hash | String | Yes      |
+| `field`   | The field to check within the hash | String | Yes      |
+
+## Return values
+
+| Condition                                      | Return Value                                      |
+|------------------------------------------------|---------------------------------------------------|
+| If the field exists within the hash            | `1`                                               |
+| If the field does not exist within the hash    | `0`                                               |
+
+## Behaviour
+
+- The `HEXISTS` command checks if the specified `field` exists within the hash stored at `key`.
+- If the specified `field` is present in the hash, `HEXISTS` returns `1`.
+- If the specified `field` is not present or if `key` does not contain a hash, it returns `0`.
+- If `key` does not exist, `HEXISTS` returns `0`.
+
+## Errors
+
+1. `Non-hash type or wrong data type`:
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs if `key` holds a non-hash data structure, such as a string or list.
+
+2. `Invalid syntax or missing parameter`:
+
+   - Error Message: `(error) ERR syntax error`
+   - Occurs if the syntax is incorrect or required parameters (`key` and `field`) are missing.
+
+## Example Usage
+
+### Basic Usage
+
+Checking if field `name` exists in the hash stored at key `user:1001`
+
+```bash
+127.0.0.1:7379> HEXISTS user:1001 name
+1
+```
+
+If the field `name` is not present
+
+```bash
+127.0.0.1:7379> HEXISTS user:1001 age
+0
+```
+
+### Checking non-existent key
+
+If the hash `user:1002` does not exist:
+
+```bash
+127.0.0.1:7379> HEXISTS user:1002 name
+0
+```
+
+## Best Practices
+
+- `Check for Field Existence`: Use `HEXISTS` to check for a field’s existence in conditional logic, especially if subsequent commands depend on the field's presence.
+
+## Alternatives
+
+- `HGET`: The `HGET` command retrieves the value of a specified field within a hash. However, unlike `HEXISTS`, it returns `nil` if the field does not exist, rather than a boolean response.
+
+## Notes
+
+- If `key` is not of type hash, consider using commands specifically designed for other data types.
+
+By utilizing the `HEXISTS` command, you can conditionally manage hash data in DiceDB, verifying field presence before performing operations based on field existence.

docs/hkeys_command_docs.md

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+---
+title: HKEYS
+description: The `HKEYS` command in DiceDB retrieves all fields in a hash stored at a given key. This command is essential for working with hash data structures, enabling retrieval of all field names for dynamic inspection or iteration.
+---
+
+The `HKEYS` command in DiceDB retrieves all fields in a hash stored at a given key. This command is essential for working with hash data structures, enabling retrieval of all field names for dynamic inspection or iteration.
+
+## Syntax
+
+```bash
+HKEYS key
+```
+
+## Parameters
+
+| Parameter | Description                        | Type   | Required |
+|-----------|------------------------------------|--------|----------|
+| `key`     | The name of the key holding a hash | String | Yes      |
+
+## Return values
+
+| Condition                                      | Return Value                                      |
+|------------------------------------------------|---------------------------------------------------|
+| If the key exists and holds a hash             | Array of field names                              |
+| If the key does not exist or is empty          | Empty array `[]`                                  |
+
+## Behaviour
+
+- The `HKEYS` command retrieves all field names within the hash stored at the specified `key`.
+- If the hash is empty or the `key` does not exist, it returns an empty array `[]`.
+- If `key` exists but does not hold a hash, an error is returned.
+
+## Errors
+
+1. `Non-hash type or wrong data type`:
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs if `key` holds a non-hash data structure, such as a string or list.
+
+2. `Missing required parameter`:
+
+   - Error Message: `(error) ERR wrong number of arguments for 'HKEYS' command`
+   - Occurs if the `key` parameter is missing from the command.
+
+## Example Usage
+
+### Basic Usage
+
+Retrieving all field names in the hash stored at key `user:1001`
+
+```bash
+127.0.0.1:7379> HKEYS user:1001
+1) "name"
+2) "age"
+3) "email"
+```
+
+### Empty hash
+
+If the hash stored at `user:1002` exists but has no fields:
+
+```bash
+127.0.0.1:7379> HKEYS user:1002
+(nil)
+```
+
+### Non-existent key
+
+If the hash `user:1003` does not exist:
+
+```bash
+127.0.0.1:7379> HKEYS user:1003
+(nil)
+```
+
+## Best Practices
+
+- `Use Before Iterating`: Use `HKEYS` to retrieve field names in dynamic applications where the field names may not be predetermined.
+
+## Alternatives
+
+- `HGETALL`: The `HGETALL` command retrieves all field-value pairs in a hash as an array, rather than only the field names.
+
+## Notes
+
+- Ensure that `key` is of type hash before using `HKEYS`, as other data types will produce errors.
+
+Using the `HKEYS` command, you can efficiently access all field names in hash structures, making it a valuable tool for dynamic data inspection in DiceDB.

docs/hvals_command_docs.md

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+---
+title: HVALS
+description: The `HVALS` command in DiceDB retrieves all values in a hash stored at a given key. This command allows you to access only the values within a hash, which is helpful for data inspection or retrieval without needing the field names.
+---
+
+The `HVALS` command in DiceDB retrieves all values in a hash stored at a given key. This command allows you to access only the values within a hash, which is helpful for data inspection or retrieval without needing the field names.
+
+## Syntax
+
+```bash
+HVALS key
+```
+
+## Parameters
+
+| Parameter | Description                        | Type   | Required |
+|-----------|------------------------------------|--------|----------|
+| `key`     | The name of the key holding a hash | String | Yes      |
+
+## Return values
+
+| Condition                                      | Return Value                                      |
+|------------------------------------------------|---------------------------------------------------|
+| If the key exists and holds a hash             | Array of values within the hash                   |
+| If the key does not exist or is empty          | Empty array `[]`                                  |
+
+## Behaviour
+
+- The `HVALS` command retrieves all values stored in the hash at the specified `key`, without returning the associated field names.
+- If the hash is empty or `key` does not exist, it returns an empty array `[]`.
+- If `key` exists but does not contain a hash, an error is returned.
+
+## Errors
+
+1. `Non-hash type or wrong data type`:
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs if `key` holds a non-hash data structure, such as a string or list.
+
+2. `Missing required parameter`:
+
+   - Error Message: `(error) ERR wrong number of arguments for 'HVALS' command`
+   - Occurs if the `key` parameter is missing from the command.
+
+## Example Usage
+
+### Basic Usage
+
+Retrieving all values in the hash stored at key `user:1001`
+
+```bash
+127.0.0.1:7379> HVALS user:1001
+1) "John Doe"
+2) "30"
+3) "[email protected]"
+```
+
+### Empty hash
+
+If the hash stored at `user:1002` exists but has no fields:
+
+```bash
+127.0.0.1:7379> HVALS user:1002
+(nil)
+```
+
+### Non-existent key
+
+If the hash `user:1003` does not exist:
+
+```bash
+127.0.0.1:7379> HVALS user:1003
+(nil)
+```
+
+## Best Practices
+
+- `Use for Values Only`: Use `HVALS` when only the values within a hash are needed without requiring field names, simplifying value extraction.
+
+## Alternatives
+
+- `HGETALL`: The `HGETALL` command retrieves all field-value pairs in a hash, providing both names and values.
+
+## Notes
+
+- Ensure `key` is a hash type to avoid errors when using `HVALS`.
+
+Using the `HVALS` command enables efficient access to all values within a hash structure in DiceDB, simplifying data retrieval when field names are unnecessary.