Migrating ('HLEN', 'HSTRLEN', 'HSCAN') DiceDB#1024 (DiceDB#1162)

* add migration & unit tests * fix : lint * chore : remove comments * test : add http integration tests * test : add websocket integration tests * test : add resp integration tests * chore : cleanup merge conflict * docs : add HSTRLEN documentation * fix : update store_eval return values * chore : fix lint * docs : cleanup HLEN/HSCAN/HSTRLEN docs * test : add missed async testcases to resp * fixed linting issues and conflicts: to speed up the process. --------- Co-authored-by: Ashwin Kulkarni <[email protected]>
lucifercr07 · Oct 24, 2024 · 12616de · 12616de
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diff --git a/docs/src/content/docs/commands/HLEN.md b/docs/src/content/docs/commands/HLEN.md
@@ -13,30 +13,42 @@ HLEN key
 
 ## Parameters
 
-- `key`: The key associated with the hash for which the number of fields is to be retrieved. This parameter is mandatory.
+| Parameter       | Description                                                                              | Type    | Required |
+|-----------------|------------------------------------------------------------------------------------------|---------|----------|
+| `key`           | The key associated with the hash for which the number of fields is to be retrieved       | String  | Yes      |
+
 
 ## Return Value
 
-The `HLEN` command returns an integer representing the number of fields in the hash stored at the specified key. If the key does not exist, it returns `0`.
+| Condition                                      | Return Value                                      |
+|------------------------------------------------|---------------------------------------------------|
+| If specified key exists                        | number of fields in the hash at key               |
+| If key doesn't exist                           | `0`                                               |
 
 ## Behaviour
 
-When the `HLEN` command is executed:
+- DiceDB checks if the specified key exists.
+- If the key exists and is associated with a hash, DiceDB counts the number of fields in the hash and returns this count.
+- If the key does not exist, DiceDB returns `0`.
+- If the key exists but is not associated with a hash, an error is returned.
+
+## Errors
+
+1. `Wrong type of key`:
 
-1. DiceDB checks if the specified key exists.
-2. If the key exists and is associated with a hash, DiceDB counts the number of fields in the hash and returns this count.
-3. If the key does not exist, DiceDB returns `0`.
-4. If the key exists but is not associated with a hash, an error is returned.
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs when attempting to use the command on a key that contains a non-hash value.
 
-## Error Handling
+2. `Wrong number of arguments`:
 
-The `HLEN` command can raise the following errors:
+   - Error Message: `(error) -ERR wrong number of arguments for 'HLEN' command`
+   - Occurs if key isn't specified in the command.
 
-- `WRONGTYPE Operation against a key holding the wrong kind of value`: This error occurs if the specified key exists but is not associated with a hash. For example, if the key is associated with a string, list, set, or any other data type, this error will be raised.
 
 ## Example Usage
 
-### Example 1: Basic Usage
+### Basic Usage
+Creating hash `myhash` with two fields `field1` and `field2`. Getting hash length of `myhash`.
 
 ```DiceDB
 > HSET myhash field1 "value1" field2 "value2"
@@ -46,18 +58,16 @@ The `HLEN` command can raise the following errors:
 (integer) 2
 ```
 
-In this example, the hash `myhash` is created with two fields, `field1` and `field2`. The `HLEN` command returns `2`, indicating that there are two fields in the hash.
-
-### Example 2: Non-Existent Key
+### Invalid Usage on non-existent key
+Getting hash length from a non-existent hash key `nonExistentHash`.
 
 ```DiceDB
 > HLEN nonExistentHash
 (integer) 0
 ```
 
-In this example, the key `nonExistentHash` does not exist. The `HLEN` command returns `0`, indicating that there are no fields in the hash because the hash itself does not exist.
-
-### Example 3: Key with Wrong Data Type
+### Invalid Usage on non-hash key
+Getting hash length from a key `mystring` associated with a non-hash type.
 
 ```DiceDB
 > SET mystring "This is a string"
@@ -67,9 +77,7 @@ OK
 (error) WRONGTYPE Operation against a key holding the wrong kind of value
 ```
 
-In this example, the key `mystring` is associated with a string value. When the `HLEN` command is executed on this key, it raises an error because the key is not associated with a hash.
-
-## Additional Notes
+## Notes
 
 - The `HLEN` command is a constant-time operation, meaning its execution time is O(1) regardless of the number of fields in the hash.
 - This command is useful for quickly determining the size of a hash without needing to retrieve all the fields and values.

diff --git a/docs/src/content/docs/commands/HSCAN.md b/docs/src/content/docs/commands/HSCAN.md
@@ -13,34 +13,43 @@ HSCAN key cursor [MATCH pattern] [COUNT count]
 
 ## Parameters
 
-- `key`: The key of the hash to scan.
-- `cursor`: The cursor indicating the starting position of the scan.
-- `MATCH pattern` (optional): Specifies a pattern to match against the fields. Only the fields that match the pattern will be returned.
-- `COUNT count` (optional): Specifies the maximum number of fields to return.
+| Parameter       | Description                                                                                              | Type     | Required |
+|-----------------|----------------------------------------------------------------------------------------------------------|---------|----------|
+| `key`           | The key of the hash to scan.                                                                             | String   | Yes      |
+| `cursor`        | The cursor indicating the starting position of the scan.                                                 | String   | Yes      |
+| `MATCH pattern` | Specifies a pattern to match against the fields. Only the fields that match the pattern will be returned.| String   | No       |
+| `COUNT count`   | Specifies the maximum number of fields to return.                                                        | String   | Yes      |
+
 
 ## Return Value
 
 The `HSCAN` command returns an array containing the next cursor and the matching fields. The format of the returned array is `[nextCursor, [field1, value1, field2, value2, ...]]`.
 
 ## Behaviour
-When the `HSCAN` command is executed:
 
-1. DiceDB checks if the specified key exists.
-2. If the key exists and is associated with a hash, DiceDB scans the fields of the hash and returns the next cursor and the matching fields.
-3. If the key does not exist, DiceDB returns an empty array.
-4. If the key exists but is not associated with a hash, an error is returned.
-5. If the key exists and all keys have been scanned, cursor is reset to 0.
+- DiceDB checks if the specified key exists.
+- If the key exists and is associated with a hash, DiceDB scans the fields of the hash and returns the next cursor and the matching fields.
+- If the key does not exist, DiceDB returns an empty array.
+- If the key exists but is not associated with a hash, an error is returned.
+- If the key exists and all keys have been scanned, cursor is reset to 0.
 
 ## Error handling
-The `HSCAN` command can raise the following errors:
 
-- `WRONGTYPE Operation against a key holding the wrong kind of value`: This error occurs if the specified key exists but is not associated with a hash. For example, if the key is associated with a string, list, set, or any other data type, this error will be raised.
-- `Invalid integer value for COUNT`: This error occurs if the value provided for the `COUNT` option is not a valid integer or is out of range.
+1. `Wrong type of key`:
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs when attempting to use the command on a key that contains a non-hash value.
 
+2. `Invalid integer`:
 
+   - Error Message: `(error) Invalid integer value for COUNT`
+   - Occurs if the value provided for the `COUNT` option is not a valid integer or is out of range.
 
 ## Examples
 
+### Basic Usage
+Creating a hash `myhash` with two fields `field1` and `field2`. Getting `HSCAN` on `myhash` with valid cursors.
+
 ```bash
 > HSET myhash field1 "value1" field2 "value2"
 1) (integer) 2
@@ -62,9 +71,16 @@ The `HSCAN` command can raise the following errors:
 2) 1) "field2"
    2) "value2"
 ```
+### Invalid Usage on non-existent key
+Getting `HSCAN` on nonExistentHash.
 
+```bash
+> HSCAN nonExistentHash 0
+1) "0"
+2) (empty array)
+```
 
-## Additional Notes
+## Notes
 
 - The `HSCAN` command has a time complexity of O(N), where N is the number of keys in the hash. This is in contrast to Redis, which implements `HSCAN` in O(1) time complexity by maintaining a cursor.
 - The `HSCAN` command is particularly useful for iterating over the fields of a hash in a cursor-based manner, allowing for efficient processing of large hashes.

diff --git a/docs/src/content/docs/commands/HSTRLEN.md b/docs/src/content/docs/commands/HSTRLEN.md
@@ -0,0 +1,82 @@
+---
+title: HSTRLEN
+description: Documentation for the DiceDB command HSTRLEN
+---
+
+The `HSTRLEN` command in DiceDB is used to obtain the string length of value associated with field in the hash stored at a specified key. 
+
+## Syntax
+
+```
+HSTRLEN key field
+```
+
+## Parameters
+
+| Parameter       | Description                                                                              | Type    | Required |
+|-----------------|------------------------------------------------------------------------------------------|---------|----------|
+| `key`           | The key of the hash, which consists of the field whose string length you want to obtain  | String  | Yes      |
+| `field`         | The field present in the hash whose length you want to obtain                            | String  | Yes      |
+
+## Return Value
+
+| Condition                                      | Return Value                                      |
+|------------------------------------------------|---------------------------------------------------|
+| If specified key and field exists              | string length                                     |
+| If key doesn't exist                           | `0`                                               |
+| If field doesn't exist                         | `0`                                               |
+
+## Behaviour
+
+- DiceDB checks if the specified key exists.
+- If the key exists, is associated with a hash and specified field exists in the hash, DiceDB returns the string length of value associated with specified field in the hash.
+- If the key does not exist, DiceDB returns `0`.
+- If the key exists and specified field does not exist in the key, DiceDB returns `0`.
+
+## Errors
+
+1. `Wrong type of key`:
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs when attempting to use the command on a key that contains a non-hash value.
+
+2. `Wrong number of arguments`:
+
+   - Error Message: `(error) -ERR wrong number of arguments for 'hstrlen' command`
+   - Occurs if key or field isn't specified in the command.
+
+## Example Usage
+
+### Basic Usage
+Creating hash `myhash` with two fields `field1` and `field2`. Getting string length of value in `field1`.
+
+```DiceDB
+> HSET myhash field1 "helloworld" field2 "value2"
+(integer) 1
+
+> HSTRLEN myhash field1
+(integer) 10
+```
+
+### Invalid Usage on non-existent key
+Getting string length from a non-existent key `nonExistentHash`.
+
+```DiceDB
+> HSTRLEN nonExistentHash field1
+(integer) 0
+```
+
+### Invalid Usage on non-hash key
+Getting string length from a key `mystring` associated with a non-hash type.
+
+```DiceDB
+> SET mystring "This is a string"
+OK
+
+> HSTRLEN mystring field1
+(error) WRONGTYPE Operation against a key holding the wrong kind of value
+```
+
+## Notes
+
+- The `HSTRLEN` command has a constant-time operation, meaning its execution time is O(1), regardless of the number of fields in the hash.
diff --git a/integration_tests/commands/async/hlen_test.go b/integration_tests/commands/async/hlen_test.go
diff --git a/integration_tests/commands/async/hscan_test.go b/integration_tests/commands/async/hscan_test.go