How to Create Complex Filter Expressions with Multiple Conditions in AWS SDK for Go?

How to Add Multiple Conditions to FilterExpression Using AWS SDK for Go

The AWS SDK for Go provides an expression builder for simplifying the task of creating complex filter expressions for DynamoDB Scan operations. By default, attempting to add multiple conditions using the expression builder overwrites the previous condition, leaving you with a single filter.

Approach Using ConditionBuilder Structure

To overcome this limitation, the ConditionBuilder structure offers methods to combine multiple conditions using logical operators. For example, the following code demonstrates how to add multiple conditions using the And() method:

<code class="go">cond1 := expression.Name("foo").Equal(expression.Value(5))
cond2 := expression.Name("bar").Equal(expression.Value(6))
expr, err := expression.NewBuilder().
    WithCondition(cond1.And(cond2)).
    Build()</code>

Alternatively, you can use the Or() and Not() methods to combine conditions with OR and NOT logic, respectively.

Alternative Approach: Manual Expression Building

If you prefer to construct the filter expression manually, you can use the expression.New() function to create an Expression object and then append conditions using the And() or Or() methods. For example:

<code class="go">expr := expression.New()
expr.AndWith(expression.Name("foo").Equal(expression.Value(5)))
expr.OrWith(expression.Name("bar").Equal(expression.Value(6)))</code>

Documentation Reference

For more information on using the expression builder, refer to the AWS SDK for Go documentation on [ExpressionBuilder](https://pkg.go.dev/github.com/aws/aws-sdk-go/aws/dynamodb/expression#ConditionBuilder).

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