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Azure Table storage output bindings for Azure Functions	Understand how to use Azure Table storage output bindings in Azure Functions.	craigshoemaker	reference	09/03/2018	cshoe	devx-track-csharp, devx-track-python

Azure Table storage output bindings for Azure Functions

Use an Azure Table storage output binding to write entities to a table in an Azure Storage account.

Note

This output binding does not support updating existing entities. Use the TableOperation.Replace operation from the Azure Storage SDK to update an existing entity.

Example

C#

The following example shows a C# function that uses an HTTP trigger to write a single table row.

public class TableStorage
{
    public class MyPoco
    {
        public string PartitionKey { get; set; }
        public string RowKey { get; set; }
        public string Text { get; set; }
    }

    [FunctionName("TableOutput")]
    [return: Table("MyTable")]
    public static MyPoco TableOutput([HttpTrigger] dynamic input, ILogger log)
    {
        log.LogInformation($"C# http trigger function processed: {input.Text}");
        return new MyPoco { PartitionKey = "Http", RowKey = Guid.NewGuid().ToString(), Text = input.Text };
    }
}

C# Script

The following example shows a table output binding in a function.json file and C# script code that uses the binding. The function writes multiple table entities.

Here's the function.json file:

{
  "bindings": [
    {
      "name": "input",
      "type": "manualTrigger",
      "direction": "in"
    },
    {
      "tableName": "Person",
      "connection": "MyStorageConnectionAppSetting",
      "name": "tableBinding",
      "type": "table",
      "direction": "out"
    }
  ],
  "disabled": false
}

The configuration section explains these properties.

Here's the C# script code:

public static void Run(string input, ICollector<Person> tableBinding, ILogger log)
{
    for (int i = 1; i < 10; i++)
        {
            log.LogInformation($"Adding Person entity {i}");
            tableBinding.Add(
                new Person() { 
                    PartitionKey = "Test", 
                    RowKey = i.ToString(), 
                    Name = "Name" + i.ToString() }
                );
        }

}

public class Person
{
    public string PartitionKey { get; set; }
    public string RowKey { get; set; }
    public string Name { get; set; }
}

Java

The following example shows a Java function that uses an HTTP trigger to write a single table row.

public class Person {
    private String PartitionKey;
    private String RowKey;
    private String Name;

    public String getPartitionKey() {return this.PartitionKey;}
    public void setPartitionKey(String key) {this.PartitionKey = key; }
    public String getRowKey() {return this.RowKey;}
    public void setRowKey(String key) {this.RowKey = key; }
    public String getName() {return this.Name;}
    public void setName(String name) {this.Name = name; }
}

public class AddPerson {

    @FunctionName("addPerson")
    public HttpResponseMessage get(
            @HttpTrigger(name = "postPerson", methods = {HttpMethod.POST}, authLevel = AuthorizationLevel.FUNCTION, route="persons/{partitionKey}/{rowKey}") HttpRequestMessage<Optional<Person>> request,
            @BindingName("partitionKey") String partitionKey,
            @BindingName("rowKey") String rowKey,
            @TableOutput(name="person", partitionKey="{partitionKey}", rowKey = "{rowKey}", tableName="%MyTableName%", connection="MyConnectionString") OutputBinding<Person> person,
            final ExecutionContext context) {

        Person outPerson = new Person();
        outPerson.setPartitionKey(partitionKey);
        outPerson.setRowKey(rowKey);
        outPerson.setName(request.getBody().get().getName());

        person.setValue(outPerson);

        return request.createResponseBuilder(HttpStatus.OK)
                        .header("Content-Type", "application/json")
                        .body(outPerson)
                        .build();
    }
}

The following example shows a Java function that uses an HTTP trigger to write multiple table rows.

public class Person {
    private String PartitionKey;
    private String RowKey;
    private String Name;

    public String getPartitionKey() {return this.PartitionKey;}
    public void setPartitionKey(String key) {this.PartitionKey = key; }
    public String getRowKey() {return this.RowKey;}
    public void setRowKey(String key) {this.RowKey = key; }
    public String getName() {return this.Name;}
    public void setName(String name) {this.Name = name; }
}

public class AddPersons {

    @FunctionName("addPersons")
    public HttpResponseMessage get(
            @HttpTrigger(name = "postPersons", methods = {HttpMethod.POST}, authLevel = AuthorizationLevel.FUNCTION, route="persons/") HttpRequestMessage<Optional<Person[]>> request,
            @TableOutput(name="person", tableName="%MyTableName%", connection="MyConnectionString") OutputBinding<Person[]> persons,
            final ExecutionContext context) {

        persons.setValue(request.getBody().get());

        return request.createResponseBuilder(HttpStatus.OK)
                        .header("Content-Type", "application/json")
                        .body(request.getBody().get())
                        .build();
    }
}

JavaScript

The following example shows a table output binding in a function.json file and a JavaScript function that uses the binding. The function writes multiple table entities.

Here's the function.json file:

{
  "bindings": [
    {
      "name": "input",
      "type": "manualTrigger",
      "direction": "in"
    },
    {
      "tableName": "Person",
      "connection": "MyStorageConnectionAppSetting",
      "name": "tableBinding",
      "type": "table",
      "direction": "out"
    }
  ],
  "disabled": false
}

The configuration section explains these properties.

Here's the JavaScript code:

module.exports = function (context) {

    context.bindings.tableBinding = [];

    for (var i = 1; i < 10; i++) {
        context.bindings.tableBinding.push({
            PartitionKey: "Test",
            RowKey: i.toString(),
            Name: "Name " + i
        });
    }

    context.done();
};

PowerShell

The following example demonstrates how to write multiple entities to a table from a function.

Binding configuration in function.json:

{
  "bindings": [
    {
      "name": "InputData",
      "type": "manualTrigger",
      "direction": "in"
    },
    {
      "tableName": "Person",
      "connection": "MyStorageConnectionAppSetting",
      "name": "TableBinding",
      "type": "table",
      "direction": "out"
    }
  ],
  "disabled": false
}

PowerShell code in run.ps1:

param($InputData, $TriggerMetadata)
  
foreach ($i in 1..10) {
    Push-OutputBinding -Name TableBinding -Value @{
        PartitionKey = 'Test'
        RowKey = "$i"
        Name = "Name $i"
    }
}

Python

The following example demonstrates how to use the Table storage output binding. The table binding is configured in the function.json by assigning values to name, tableName, partitionKey, and connection:

{
  "scriptFile": "__init__.py",
  "bindings": [
    {
      "name": "message",
      "type": "table",
      "tableName": "messages",
      "partitionKey": "message",
      "connection": "AzureWebJobsStorage",
      "direction": "out"
    },
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "methods": [
        "get",
        "post"
      ]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "$return"
    }
  ]
}

The following function generates a unique UUI for the rowKey value and persists the message into Table storage.

import logging
import uuid
import json

import azure.functions as func

def main(req: func.HttpRequest, message: func.Out[str]) -> func.HttpResponse:

    rowKey = str(uuid.uuid4())

    data = {
        "Name": "Output binding message",
        "PartitionKey": "message",
        "RowKey": rowKey
    }

    message.set(json.dumps(data))

    return func.HttpResponse(f"Message created with the rowKey: {rowKey}")

Attributes and annotations

C#

In C# class libraries, use the TableAttribute.

The attribute's constructor takes the table name. The attribute can be used on an out parameter or on the return value of the function, as shown in the following example:

[FunctionName("TableOutput")]
[return: Table("MyTable")]
public static MyPoco TableOutput(
    [HttpTrigger] dynamic input, 
    ILogger log)
{
    ...
}

You can set the Connection property to specify the storage account to use, as shown in the following example:

[FunctionName("TableOutput")]
[return: Table("MyTable", Connection = "StorageConnectionAppSetting")]
public static MyPoco TableOutput(
    [HttpTrigger] dynamic input, 
    ILogger log)
{
    ...
}

For a complete example, see the C# example.

You can use the StorageAccount attribute to specify the storage account at class, method, or parameter level. For more information, see Input - attributes.

C# Script

Attributes are not supported by C# Script.

Java

In the Java functions runtime library, use the TableOutput annotation on parameters to write values into table storage.

See the example for more detail.

JavaScript

Attributes are not supported by JavaScript.

PowerShell

Attributes are not supported by PowerShell.

Python

Attributes are not supported by Python.

Configuration

The following table explains the binding configuration properties that you set in the function.json file and the Table attribute.

function.json property	Attribute property	Description
type	n/a	Must be set to `table`. This property is set automatically when you create the binding in the Azure portal.
direction	n/a	Must be set to `out`. This property is set automatically when you create the binding in the Azure portal.
name	n/a	The variable name used in function code that represents the table or entity. Set to `$return` to reference the function return value.
tableName	TableName	The name of the table.
partitionKey	PartitionKey	The partition key of the table entity to write. See the usage section for guidance on how to use this property.
rowKey	RowKey	The row key of the table entity to write. See the usage section for guidance on how to use this property.
connection	Connection	The name of an app setting that contains the Storage connection string to use for this binding. If the app setting name begins with "AzureWebJobs", you can specify only the remainder of the name here. For example, if you set `connection` to "MyStorage", the Functions runtime looks for an app setting that is named "MyStorage". If you leave `connection` empty, the Functions runtime uses the default Storage connection string in the app setting that is named `AzureWebJobsStorage`.

[!INCLUDE app settings to local.settings.json]

Usage

C#

Access the output table entity by using a method parameter ICollector<T> paramName or IAsyncCollector<T> paramName where T includes the PartitionKey and RowKey properties. These properties are often accompanied by implementing ITableEntity or inheriting TableEntity.

Alternatively you can use a CloudTable method parameter to write to the table by using the Azure Storage SDK. If you try to bind to CloudTable and get an error message, make sure that you have a reference to the correct Storage SDK version.

C# Script

Access the output table entity by using a method parameter ICollector<T> paramName or IAsyncCollector<T> paramName where T includes the PartitionKey and RowKey properties. These properties are often accompanied by implementing ITableEntity or inheriting TableEntity. The paramName value is specified in the name property of function.json.

Alternatively you can use a CloudTable method parameter to write to the table by using the Azure Storage SDK. If you try to bind to CloudTable and get an error message, make sure that you have a reference to the correct Storage SDK version.

Java

There are two options for outputting a Table storage row from a function by using the TableStorageOutput annotation:

Return value: By applying the annotation to the function itself, the return value of the function is persisted as a Table storage row.
Imperative: To explicitly set the message value, apply the annotation to a specific parameter of the type OutputBinding<T>, where T includes the PartitionKey and RowKey properties. These properties are often accompanied by implementing ITableEntity or inheriting TableEntity.

JavaScript

Access the output event by using context.bindings.<name> where <name> is the value specified in the name property of function.json.

PowerShell

To write to table data, use the Push-OutputBinding cmdlet, set the -Name TableBinding parameter and -Value parameter equal to the row data. See the PowerShell example for more detail.

Python

There are two options for outputting a Table storage row message from a function:

Return value: Set the name property in function.json to $return. With this configuration, the function's return value is persisted as a Table storage row.
Imperative: Pass a value to the set method of the parameter declared as an Out type. The value passed to set is persisted as an Event Hub message.

Exceptions and return codes

Binding	Reference
Table	Table Error Codes
Blob, Table, Queue	Storage Error Codes
Blob, Table, Queue	Troubleshooting

Next steps

[!div class="nextstepaction"] Learn more about Azure functions triggers and bindings

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functions-bindings-storage-table-output.md

functions-bindings-storage-table-output.md

Azure Table storage output bindings for Azure Functions

Example

C#

C# Script

Java

JavaScript

PowerShell

Python

Attributes and annotations

C#

C# Script

Java

JavaScript

PowerShell

Python

Configuration

Usage

C#

C# Script

Java

JavaScript

PowerShell

Python

Exceptions and return codes

Next steps

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functions-bindings-storage-table-output.md

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functions-bindings-storage-table-output.md

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Azure Table storage output bindings for Azure Functions

Example

Attributes and annotations

Configuration

Usage

Exceptions and return codes

Next steps