Filters & Expressions

Filters allow you to select specific items from arrays based on conditions. Using the ?() operator, you can query data, perform conditional selection, and extract exactly what you need.

Filters are a standard JSONPath feature that enables SQL-like querying of JSON data structures.

Filter Syntax

Filters use the ?() operator with conditional expressions:

$.array[?(expression)]

? - Indicates a filter operation
(expression) - The condition to evaluate
@ - References the current item being filtered

{
  "activeUsers": "$.users[?(@.active===true)]"
}

{
  "users": [
    {"name": "Alice", "active": true},
    {"name": "Bob", "active": false},
    {"name": "Charlie", "active": true}
  ]
}

{
  "activeUsers": [
    {"name": "Alice", "active": true},
    {"name": "Charlie", "active": true}
  ]
}

Filters always return an array, even if only one item matches. To get a single item, you can combine with array indexing: $.users[?(@.active===true)][0]

The @ Symbol

Inside filter expressions, @ represents the current item being evaluated.

Basic @ Usage
Nested Properties
Property Existence

Filter

{
  "expensiveItems": "$.products[?(@.price>100)]"
}

Data

{
  "products": [
    {"name": "Widget", "price": 29.99},
    {"name": "Gadget", "price": 149.99},
    {"name": "Doohickey", "price": 199.99}
  ]
}

Result

{
  "expensiveItems": [
    {"name": "Gadget", "price": 149.99},
    {"name": "Doohickey", "price": 199.99}
  ]
}

@ refers to each product object as it’s evaluated.

Filter

{
  "bostonUsers": "$.users[?(@.address.city===Boston)]"
}

Data

{
  "users": [
    {"name": "Alice", "address": {"city": "Boston"}},
    {"name": "Bob", "address": {"city": "New York"}},
    {"name": "Charlie", "address": {"city": "Boston"}}
  ]
}

Result

{
  "bostonUsers": [
    {"name": "Alice", "address": {"city": "Boston"}},
    {"name": "Charlie", "address": {"city": "Boston"}}
  ]
}

Use @.property.nested to access nested values.

Filter

{
  "withISBN": "$.books[?(@.isbn)]"
}

Data

{
  "books": [
    {"title": "Book A", "isbn": "123"},
    {"title": "Book B"},
    {"title": "Book C", "isbn": "456"}
  ]
}

Result

{
  "withISBN": [
    {"title": "Book A", "isbn": "123"},
    {"title": "Book C", "isbn": "456"}
  ]
}

?(@.isbn) checks if the property exists and is truthy.

Comparison Operators

Use JavaScript comparison operators in filter expressions:

Equality
Numeric Comparisons
String Comparisons

Filters

{
  "admins": "$.users[?(@.role===admin)]",
  "notAdmins": "$.users[?(@.role!==admin)]",
  "active": "$.users[?(@.active===true)]",
  "inactive": "$.users[?(@.active===false)]"
}

Operators:

=== - Strict equality (recommended)
!== - Strict inequality
== - Loose equality
!= - Loose inequality

Filters

{
  "expensive": "$.products[?(@.price>100)]",
  "affordable": "$.products[?(@.price<=50)]",
  "inRange": "$.products[?(@.price>=20 && @.price<=100)]"
}

Operators:

> - Greater than
< - Less than
>= - Greater than or equal
<= - Less than or equal

Filters

{
  "startsWithA": "$.users[?(@.name[0]===A)]",
  "longNames": "$.users[?(@.name.length>10)]",
  "hasEmail": "$.users[?(@.email)]"
}

You can access string properties like length and array index [0].

Comparison Operators Reference

Operator	Description	Example
`===`	Strict equal	`?(@.status===active)`
`!==`	Strict not equal	`?(@.status!==deleted)`
`==`	Loose equal	`?(@.count==5)`
`!=`	Loose not equal	`?(@.count!=0)`
`>`	Greater than	`?(@.price>100)`
`<`	Less than	`?(@.age<18)`
`>=`	Greater or equal	`?(@.score>=80)`
`<=`	Less or equal	`?(@.quantity<=10)`

Use === (strict equality) instead of == to avoid type coercion issues. For example, 5 == "5" is true, but 5 === "5" is false.

Logical Operators

Combine multiple conditions with logical operators:

AND (&&)
OR (||)
Complex Logic

Filter

{
  "premiumActive": "$.users[?(@.tier===premium && @.active===true)]"
}

Data

{
  "users": [
    {"name": "Alice", "tier": "premium", "active": true},
    {"name": "Bob", "tier": "premium", "active": false},
    {"name": "Charlie", "tier": "basic", "active": true}
  ]
}

Result

{
  "premiumActive": [
    {"name": "Alice", "tier": "premium", "active": true}
  ]
}

Both conditions must be true.

Filter

{
  "highPriority": "$.tasks[?(@.priority===urgent || @.priority===high)]"
}

Data

{
  "tasks": [
    {"title": "Task A", "priority": "urgent"},
    {"title": "Task B", "priority": "low"},
    {"title": "Task C", "priority": "high"}
  ]
}

Result

{
  "highPriority": [
    {"title": "Task A", "priority": "urgent"},
    {"title": "Task C", "priority": "high"}
  ]
}

Either condition can be true.

Filter

{
  "qualified": "$.candidates[?(@.experience>5 && (@.degree===Masters || @.degree===PhD))]"
}

Data

{
  "candidates": [
    {"name": "Alice", "experience": 7, "degree": "Masters"},
    {"name": "Bob", "experience": 3, "degree": "PhD"},
    {"name": "Charlie", "experience": 10, "degree": "Bachelors"}
  ]
}

Result

{
  "qualified": [
    {"name": "Alice", "experience": 7, "degree": "Masters"}
  ]
}

Combine multiple AND/OR conditions with parentheses.

Advanced Filter Variables

JSONPath Plus provides special variables for accessing related data:

@root
@parent
@property
@path

Access the root document from within a filter:

Filter

{
  "matchingOrders": "$.orders[?(@.customerId===@root.trigger.customer_id)]"
}

Data

{
  "trigger": {
    "customer_id": "CUST-123"
  },
  "orders": [
    {"id": "ORD-1", "customerId": "CUST-123"},
    {"id": "ORD-2", "customerId": "CUST-456"},
    {"id": "ORD-3", "customerId": "CUST-123"}
  ]
}

Result

{
  "matchingOrders": [
    {"id": "ORD-1", "customerId": "CUST-123"},
    {"id": "ORD-3", "customerId": "CUST-123"}
  ]
}

@root lets you compare array items against trigger data or other nodes.

Access the parent object of the current item:

Filter

{
  "premiumProducts": "$.categories..products[?(@parent.tier===premium)]"
}

Data

{
  "categories": [
    {
      "name": "Electronics",
      "tier": "premium",
      "products": [{"name": "Laptop"}, {"name": "Phone"}]
    },
    {
      "name": "Accessories",
      "tier": "basic",
      "products": [{"name": "Cable"}, {"name": "Case"}]
    }
  ]
}

Result

{
  "premiumProducts": [
    {"name": "Laptop"},
    {"name": "Phone"}
  ]
}

Access the property name or array index of the current item:

Filter

{
  "notFirst": "$.items[?(@property!==0)]"
}

Data

{
  "items": ["Apple", "Banana", "Cherry"]
}

Result

{
  "notFirst": ["Banana", "Cherry"]
}

@property is the index (0, 1, 2) for array items.

Access the JSONPath string to the current item:

Filter

{
  "notFirstBook": "$.store.book[?(@path!==\"$['store']['book'][0]\")]"
}

Useful for excluding specific paths or comparing locations.

Filter Variables Reference

Variable	Description	Example
`@`	Current item	`?(@.price>10)`
`@.property`	Item’s property	`?(@.active===true)`
`@root`	Root document	`?(@.id===@root.trigger.id)`
`@parent`	Parent object	`?(@parent.category===premium)`
`@property`	Property name/index	`?(@property!==0)`
`@parentProperty`	Parent’s property name	`?(@parentProperty!==hidden)`
`@path`	JSONPath to item	`?(@path!==\"$[0]\")`

Type Selectors in Filters

Filter by data type using type selector operators:

Primitive Types
Complex Types
Numeric Types

Filters

{
  "stringValues": "$.data[*][?(@string())]",
  "numberValues": "$.data[*][?(@number())]",
  "booleanValues": "$.data[*][?(@boolean())]"
}

Data

{
  "data": [
    {"value": "text"},
    {"value": 42},
    {"value": true},
    {"value": "another string"}
  ]
}

Select items by their type.

Filters

{
  "arrays": "$.data[*][?(@array())]",
  "objects": "$.data[*][?(@object())]",
  "nullValues": "$.data[*][?(@null())]"
}

Data

{
  "data": [
    {"value": [1, 2, 3]},
    {"value": {"nested": true}},
    {"value": null},
    {"value": "text"}
  ]
}

Filters

{
  "integers": "$.data[*][?(@integer())]",
  "allNumbers": "$.data[*][?(@number())]"
}

Data

{
  "data": [
    {"value": 42},
    {"value": 3.14},
    {"value": 100},
    {"value": "text"}
  ]
}

Result

{
  "integers": [{"value": 42}, {"value": 100}],
  "allNumbers": [{"value": 42}, {"value": 3.14}, {"value": 100}]
}

Type Selectors Reference

Selector	Matches	Example
`@string()`	String values	`?(@string())`
`@number()`	All numbers	`?(@number())`
`@integer()`	Integer numbers only	`?(@integer())`
`@boolean()`	true or false	`?(@boolean())`
`@array()`	Arrays	`?(@array())`
`@object()`	Objects	`?(@object())`
`@null()`	null values	`?(@null())`
`@scalar()`	Non-object/non-function	`?(@scalar())`

Complex Filter Patterns

Range Filtering
Multiple Conditions
Exclusion Filtering
Nested Array Filtering
Cross-Reference

Filter

{
  "midRange": "$.products[?(@.price>=50 && @.price<=150)]"
}

Select items within a numeric range.

Filter

{
  "qualified": "$.users[?(@.active===true && @.verified===true && @.score>=80)]"
}

Require multiple conditions to all be true.

Filter

{
  "notDeleted": "$.items[?(@.status!==deleted && @.status!==archived)]"
}

Exclude items with specific values.

Filter

{
  "hasHighPriorityTask": "$.users[?(@.tasks[?(@.priority===high)])]"
}

Filter based on nested array contents (users who have high-priority tasks).

Filter

{
  "matchingItems": "$.node.items[?(@.categoryId===@root.trigger.selected_category)]"
}

Filter array items against trigger data or other node values.

Real-World Examples

E-commerce Orders
User Management
Inventory Management
Task Management

Filters

{
  "recentOrders": "$.orders[?(@.total>100 && @.status===completed)]",
  "pendingHighValue": "$.orders[?(@.status===pending && @.total>500)]",
  "freeShipping": "$.orders[?(@.total>=50)]",
  "needsReview": "$.orders[?(@.total>1000 && @.verified===false)]"
}

Common e-commerce filtering patterns.

Filters

{
  "activeAdmins": "$.users[?(@.role===admin && @.active===true)]",
  "suspendedUsers": "$.users[?(@.status===suspended)]",
  "newUsers": "$.users[?(@.createdDays<30)]",
  "premiumExpiring": "$.users[?(@.tier===premium && @.daysUntilExpiry<7)]"
}

Filters

{
  "lowStock": "$.products[?(@.quantity<10)]",
  "outOfStock": "$.products[?(@.quantity===0)]",
  "needsReorder": "$.products[?(@.quantity<@.reorderPoint)]",
  "highValue": "$.products[?(@.quantity*@.price>10000)]"
}

Inventory alerts and monitoring.

Filters

{
  "urgent": "$.tasks[?(@.priority===urgent && @.status!==completed)]",
  "overdue": "$.tasks[?(@.dueDate<@root.trigger.currentDate && @.status!==completed)]",
  "myTasks": "$.tasks[?(@.assignedTo===@root.trigger.user_id)]",
  "blockedTasks": "$.tasks[?(@.blockedBy)]"
}

Combining Filters with Other Operations

Filter + Array Index
Filter + Property Access
Filter + Pipe Operator
Multiple Filters

Mapping

{
  "firstActive": "$.users[?(@.active===true)][0]",
  "lastPremium": "$.users[?(@.tier===premium)][-1]"
}

Get a single item from filtered results.

Mapping

{
  "activeUserNames": "$.users[?(@.active===true)].name",
  "premiumEmails": "$.users[?(@.tier===premium)].email"
}

Extract specific properties from filtered items.

Mapping

{
  "activeList": "Active users: |$.users[?(@.active===true)].name|",
  "count": "Found |$.products[?(@.price>100)].length| expensive items"
}

Use filtered results in string concatenation.

Mapping

{
  "specific": "$.categories[?(@.name===Electronics)].products[?(@.price<100)]"
}

Chain filters to narrow down results progressively.

Common Pitfalls

Using = instead of ===

Wrong:

"$.users[?(@.role=admin)]"  // ❌ Single = is assignment, not comparison

Correct:

"$.users[?(@.role===admin)]"  // ✅ Use === for comparison

Forgetting Quotes for Strings

Wrong:

"$.users[?(@.status===active)]"  // ❌ Missing quotes around 'active'

Correct:

"$.users[?(@.status==='active')]"  // ✅ Strings need quotes

Note: In some implementations, quotes are optional, but it’s best practice to include them.

Filter Returns Array

Issue:

{"user": "$.users[?(@.id===123)]"}  // Returns array, not single object

Solution:

{"user": "$.users[?(@.id===123)][0]"}  // Add [0] to get first item

Property Doesn't Exist

Issue:

"$.users[?(@.middleName===Smith)]"  // What if middleName doesn't exist?

Better:

"$.users[?(@.middleName && @.middleName===Smith)]"  // Check existence first

Performance Considerations

Efficient Filters

// ✅ Simple conditions
"$.users[?(@.active===true)]"

// ✅ Direct property checks
"$.items[?(@.price>100)]"

Slower Filters

// ⚠️ Complex nested filters
"$.data[?(@.nested[?(@.x>5)])]"

// ⚠️ Many conditions
"$.items[?(@.a && @.b && @.c && @.d)]"

Optimization tips:

Filter early in your JSONPath expression to reduce data being processed
Use simple conditions when possible
Consider splitting complex filters into multiple steps
Test with realistic data sizes

Building Complex Filters

Start Simple

Begin with a basic filter:

{"filtered": "$.items[?(@.price>10)]"}

Add One Condition

Add conditions incrementally:

{"filtered": "$.items[?(@.price>10 && @.active===true)]"}

Test Each Addition

Verify the filter works after each change using the Flow Debugger

Use Parentheses for Complex Logic

Group conditions clearly:

{"filtered": "$.items[?(@.price>10 && (@.category===A || @.category===B))]"}

Consider Readability

If the filter becomes too complex, consider:

Breaking into multiple filters
Using separate nodes for each filter step
Adding comments in your flow documentation

Quick Reference

Filter Syntax

$.array[?(expression)]

Always returns an array
Use @ for current item
Combine with [0] for single item

Comparison Operators

===  !==  ==  !=  >  <  >=  <=

Prefer === over == for type safety

Logical Operators

&&  (AND)
||  (OR)

Use parentheses for complex logic

Special Variables

@           Current item
@root       Root document
@parent     Parent object
@property   Property name/index
@path       JSONPath to item

What’s Next?

Advanced Techniques

Learn power user features and optimization strategies

Examples

See comprehensive real-world examples

Reference

Complete syntax tables and troubleshooting

Basic Syntax

Review the fundamentals

Questions? Check the Reference or visit our Help Center.

Get Started

Assistants

Flows

Account Management

Advanced

Filter Syntax

The @ Symbol

Comparison Operators

Comparison Operators Reference

Logical Operators

Advanced Filter Variables

Filter Variables Reference

Type Selectors in Filters

Type Selectors Reference

Complex Filter Patterns

Real-World Examples

Combining Filters with Other Operations

Common Pitfalls

Performance Considerations

Efficient Filters

Slower Filters

Building Complex Filters

Quick Reference

What’s Next?

Advanced Techniques

Examples

Reference

Basic Syntax

​Filter Syntax

​The @ Symbol

​Comparison Operators

​Comparison Operators Reference

​Logical Operators

​Advanced Filter Variables

​Filter Variables Reference

​Type Selectors in Filters

​Type Selectors Reference

​Complex Filter Patterns

​Real-World Examples

​Combining Filters with Other Operations

​Common Pitfalls

​Performance Considerations

Efficient Filters

Slower Filters

​Building Complex Filters

​Quick Reference

​What’s Next?

Advanced Techniques

Examples

Reference

Basic Syntax

Filter Syntax

The @ Symbol

Comparison Operators

Comparison Operators Reference

Logical Operators

Advanced Filter Variables

Filter Variables Reference

Type Selectors in Filters

Type Selectors Reference

Complex Filter Patterns

Real-World Examples

Combining Filters with Other Operations

Common Pitfalls

Performance Considerations

Building Complex Filters

Quick Reference

What’s Next?