Expression builder for AWS.DynamoDB.DocumentClient.
Converts a plain object to a DynamoDB expression with all variables and names replaced with safe placeholders. It supports Condition, KeyCondition, Filter, Projection and Update expressions. The resulting expressions can then be used with AWS.DynamoDB.DocumentClient requests.
import dynoexpr from '@tuplo/dynoexpr';
const params = dynoexpr({
KeyCondition: { id: '567' },
Condition: { rating: '> 4.5' },
Filter: { color: 'blue' },
Projection: ['weight', 'size'],
});
/*
{
KeyConditionExpression: '(#n0c8f = :vaa3d)',
ConditionExpression: '(#n843d > :vf170)',
FilterExpression: '(#n9bfd = :v0c8f)',
ProjectionExpression: '#ndb8f,#n1a24',
ExpressionAttributeNames: {
'#n0c8f': 'id',
'#n843d': 'rating',
'#n9bfd': 'color',
'#ndb8f': 'weight',
'#n1a24': 'size',
},
ExpressionAttributeValues: {
':vaa3d': '567',
':vf170': '4.5',
':v0c8f': 'blue',
},
}
*/Passing parameters to DocumentClient
const docClient = new AWS.DynamoDB.DocumentClient();
const params = dynoexpr({
KeyCondition: {
HashKey: 'key',
RangeKey: 'between 2015 and 2019',
},
});
const results = await docClient
.query({ TableName: 'table', ...params })
.promise();Using multiple expressions on the same field
You can hide multiple expressions on the same field, by packing them into an array and assigning it to the key with the field's name.
const params = dynoexpr({
Condition: {
color: ['attribute_not_exists', 'yellow', 'blue'],
},
logicalOperator: 'OR',
});
/*
{
ConditionExpression: '(attribute_not_exists(#n9bfd)) \
OR (#n9bfd = :va351) \
OR (#n9bfd = :v0c8f)',
ExpressionAttributeNames: {
'#n9bfd': 'color'
},
ExpressionAttributeValues: {
':va351': 'yellow',
':v0c8f': 'blue'
}
}
*/Using functions
DynamoDB supports a number of functions to be evaluated when parsing expressions. You don't need to reference the path argument because that's identified by the object's key.
const params = dynoexpr({
Condition: {
docs: 'attribute_exists',
brand: 'attribute_not_exists',
extra: 'attribute_type(NULL)',
color: 'begins_with dark',
address: 'contains(Seattle)',
description: 'size < 20',
},
});
/*
{
ConditionExpression: '(attribute_exists(#nd286)) \
AND (attribute_not_exists(#n0ed7)) \
AND (attribute_type(#na4d6,:vec29)) \
AND (begins_with(#n9bfd,:vbe37)) \
AND (contains(#n536a,:v7bff)) \
AND (size(#n2786) < :v3b84)',
ExpressionAttributeNames: {
'#nd286': 'docs',
'#n0ed7': 'brand',
'#na4d6': 'extra',
'#n9bfd': 'color',
'#n536a': 'address',
'#n2786': 'description'
},
ExpressionAttributeValues: {
':vec29': 'NULL',
':vbe37': 'dark',
':v7bff': 'Seattle',
':v3b84': 20
}
}
*/Using multiple expressions on the same request
const params = dynoexpr({
Update: { Sum: 'Sum + 20' },
Condition: { Sum: `< 100` },
});
/*
{
ConditionExpression: '(#na3d5 < :vc6dd)',
UpdateExpression: 'SET #na3d5 = #na3d5 + :v3b84'
ExpressionAttributeNames: {
'#na3d5': 'Sum'
},
ExpressionAttributeValues: {
':vc6dd': 100,
':v3b84': 20
},
}
*/Working with Sets
If a value is provided as a Set, it will be converted to DocumentClient.DynamoDbSet.
const params = dynoexpr({
Update: {
Color: new Set(['Orange', 'Purple']);
}
})
/*
{
UpdateExpression: 'SET #n7295 = :v0a80',
ExpressionAttributeNames: {
'#n7295': 'Color',
},
ExpressionAttributeValues: {
':v0a80': docClient.createSet(['Orange', 'Purple']),
},
}
*/When using UpdateAdd or UpdateDelete, arrays are converted to DynamoDbSet
const params = dynoexpr({
UpdateAdd: {
Color: ['Orange', 'Purple'];
}
})
/*
{
UpdateExpression: 'ADD #n7295 :v0a80',
ExpressionAttributeNames: {
'#n7295': 'Color',
},
ExpressionAttributeValues: {
':v0a80': docClient.createSet(['Orange', 'Purple']),
},
}
*/Keep existing Expressions, AttributeNames and AttributeValues
const params = dynoexpr({
Filter: { color: 'blue' },
ProjectionExpression: '#year',
ExpressionAttributeNames: {
'#year': 'year',
},
});
/*
{
ProjectionExpression: '#year',
FilterExpression: '(#n9bfd = :v0c8f)',
ExpressionAttributeNames: {
'#year': 'year',
'#n9bfd': 'color'
},
ExpressionAttributeValues: {
':v0c8f': 'blue'
}
}
*/Parsing atomic requests, only expressions will be replaced
You can pass the whole request parameters to dynoexpr - only the expression builders will be replaced.
const params = dynoexpr({
TableName: 'Table',
Key: { HashKey: 'key' },
ReturnConsumedCapacity: 'TOTAL',
KeyCondition: {
color: 'begins_with dark',
},
});
/*
{
TableName: 'Table',
Key: { HashKey: 'key' },
ReturnConsumedCapacity: 'TOTAL',
KeyConditionExpression: '(begins_with(#n9bfd,:vbe37))',
ExpressionAttributeNames: {
'#n9bfd': 'color'
},
ExpressionAttributeValues: {
':vbe37': 'dark'
}
}
*/Parsing Batch requests
const params = dynoexpr({
RequestItems: {
'Table-1': {
Keys: [{ foo: 'bar' }],
Projection: [`a`, `b`],
},
},
ReturnConsumedCapacity: 'TOTAL',
});
/*
{
RequestItems: {
'Table-1': {
Keys: [{ foo: 'bar' }],
ProjectionExpression: `#n2661,#n578f`,
ExpressionAttributeNames: {
'#n2661': `a`,
'#n578f': `b`,
},
},
},
ReturnConsumedCapacity: 'TOTAL',
}
*/Parsing Transact requests
const params = dynoexpr({
TransactItems: [
{
Get: {
TableName: 'Table-1',
Key: { id: 'foo' },
Projection: ['a', 'b'],
},
},
],
ReturnConsumedCapacity: 'INDEXES',
});
/*
{
TransactItems: [
{
Get: {
TableName: `Table-1`,
Key: { id: `foo` },
ProjectionExpression: `#n2661,#n578f`,
ExpressionAttributeNames: {
'#n2661': `a`,
'#n578f': `b`,
},
},
},
],
ReturnConsumedCapacity: 'INDEXES',
}
*/Type the resulting parameters
The resulting object is compatible with all DocumentClient requests, but if you want to be type-safe, dynoexpr accepts a generic type to be applied to the return value.
const params = dynoexpr<AWS.DocumentClient.UpdateItemInput>({
TableName: 'Table',
Key: 1,
UpdateSet: { color: 'pink' },
});Expression builder parameters
type DynamoDbPrimitive = string | number | boolean | object;
type DynamoDbValue =
| DynamoDbPrimitive
| DynamoDbPrimitive[]
| Set<DynamoDbPrimitive>;
// all attributes are optional, depending on what expression(s) are to be built
{
Condition: { [key: string]: DynamoDbValue },
ConditionLogicalOperator: 'AND' | 'OR',
KeyCondition: { [key: string]: DynamoDbValue },
KeyConditionLogicalOperator: 'AND' | 'OR',
FilterCondition: { [key: string]: DynamoDbValue },
FilterLogicalOperator: 'AND' | 'OR',
Projection: string[],
Update: { [key: string]: DynamoDbValue },
UpdateAction: 'SET' | 'ADD' | 'DELETE' | 'REMOVE',
UpdateSet: { [key: string]: DynamoDbValue },
UpdateAdd: { [key: string]: DynamoDbValue },
UpdateDelete: { [key: string]: DynamoDbValue },
UpdateRemove: { [key: string]: DynamoDbValue },
}Parameters accepted by AWS.DynamoDB.DocumentClient
// all attributes are optional depending on the expression(s) being built
{
ConditionExpression: string,
KeyConditionExpression: string,
FilterConditionExpression: string,
ProjectionExpression: string,
UpdateExpression: string,
ExpressionAttributeNames: { [key: string]: string },
ExpressionAtributeValues: { [key: string]: string },
}$ npm install @tuplo/dynoexpr
# or with yarn
$ yarn add @tuplo/dynoexprContributions are always welcome!
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