Daily DAX : Day 283 INFO.FUNCTIONS

 The `INFO.FUNCTIONS` DAX function in Power BI is a system function that returns a table containing metadata about all DAX functions available in the current environment. It provides details such as function names, descriptions, return types, and parameter information, making it a valuable tool for developers and analysts who need to explore or document the DAX function library programmatically.

### Syntax

```dax

INFO.FUNCTIONS()

```

- **No parameters**: The function does not require any input arguments.

- **Output**: Returns a table with the following columns:

  - **FunctionName**: The name of the DAX function (e.g., `SUM`, `FILTER`).

  - **Description**: A brief description of what the function does.

  - **ReturnType**: The data type of the value returned by the function (e.g., Integer, Table, String).

  - **ParameterInfo**: Details about the function’s parameters, including their names, types, and whether they are optional or required.

  - **Category**: The category the function belongs to (e.g., Aggregation, Filter, DateTime).

  - **IsHidden**: A boolean indicating whether the function is hidden (used internally or deprecated).

  - **Signature**: The full syntax of the function, showing how it can be used.

### Use Case

The `INFO.FUNCTIONS` function is primarily used for **metadata exploration** and **automation** tasks. Here are some practical scenarios where it is useful:

1. **Documentation Generation**:

   - Developers can use `INFO.FUNCTIONS` to create a comprehensive list of available DAX functions for documentation purposes. For example, you can export the table to Excel or another tool to build a reference guide for your team.

   - Example: Create a calculated table in Power BI to display all DAX functions in the `Aggregation` category:

     ```dax

     AggregationFunctions = FILTER(INFO.FUNCTIONS(), INFO.FUNCTIONS()[Category] = "Aggregation")

     ```

2. **Learning and Discovery**:

   - New DAX users can explore the function library to understand what functions are available, their purposes, and how to use them. For instance, filtering `INFO.FUNCTIONS` by category (e.g., `DateTime`) can help identify relevant functions for specific tasks.

   - Example: List all DateTime-related functions:

     ```dax

     DateTimeFunctions = FILTER(INFO.FUNCTIONS(), INFO.FUNCTIONS()[Category] = "DateTime")

     ```

3. **Debugging and Validation**:

   - When building complex DAX queries, you can use `INFO.FUNCTIONS` to verify the existence, parameters, or return types of specific functions, ensuring you’re using them correctly.

   - Example: Check the signature of the `CALCULATE` function:

     ```dax

     CalculateInfo = FILTER(INFO.FUNCTIONS(), INFO.FUNCTIONS()[FunctionName] = "CALCULATE")

     ```

4. **Automation and Tool Development**:

   - Developers building custom tools or scripts (e.g., for DAX code generation or validation) can use `INFO.FUNCTIONS` to retrieve metadata programmatically, enabling dynamic analysis of DAX capabilities.

   - Example: Create a table of all non-hidden functions for a custom DAX editor:

     ```dax

     VisibleFunctions = FILTER(INFO.FUNCTIONS(), INFO.FUNCTIONS()[IsHidden] = FALSE)

     ```

### Practical Example

Suppose you want to create a Power BI report that lists all DAX functions related to statistical calculations. You can create a calculated table using:

```dax

StatisticalFunctions = 

FILTER(

    INFO.FUNCTIONS(),

    INFO.FUNCTIONS()[Category] = "Statistical"

)

```

Then, visualize the results in a Power BI table visual to display columns like `FunctionName`, `Description`, and `Signature`. This can help analysts quickly reference statistical functions like `AVERAGE`, `MEDIAN`, or `STDEV.P`.

### Key Notes

- **Performance**: `INFO.FUNCTIONS` is a lightweight function as it only retrieves metadata and does not perform calculations on data.

- **Dynamic Updates**: The function reflects the DAX functions available in the current version of Power BI, so it automatically includes new functions added in updates.

- **Limitations**: It’s a metadata function, not designed for direct calculations or data transformation. It’s most useful in development or documentation contexts.

- **Availability**: Supported in Power BI Desktop, Power BI Service, and other platforms that support DAX, but the exact function set may vary slightly depending on the environment.

For more details, you can refer to Microsoft’s official DAX documentation or explore the function’s output directly in Power BI by creating a calculated table and inspecting the results.