@@ -42,19 +42,32 export const query = <T, Q, O>(store: Qu | |||||
42 | }; |
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42 | }; | |
43 | }; |
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43 | }; | |
44 |
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44 | |||
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45 | /** | |||
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46 | * Wraps the query method of the store, the resulting method takes a query | |||
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47 | * expression and returns two observable sequences. The first sequence represents | |||
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48 | * the results of the query, the second sequence provides the updates to the | |||
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49 | * query results. | |||
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50 | * | |||
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51 | * @param store The store used to query data | |||
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52 | * @param includeUpdates The flag to include item updates not only additions and | |||
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53 | * deletions. By default this flag is set to true. | |||
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54 | * @returns Two observable sequences | |||
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55 | */ | |||
45 | export const queryEx = <T, Q, O>(store: Queryable<T, Q, O>, includeUpdates = true) => |
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56 | export const queryEx = <T, Q, O>(store: Queryable<T, Q, O>, includeUpdates = true) => | |
46 | (query?: Q, options?: O): [data: QueryResults<T>, updates: QueryResults<T>] => { |
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57 | (query?: Q, options?: O): [data: QueryResults<T>, updates: QueryResults<T>] => { | |
47 |
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58 | |||
48 | const pending: T[] = []; |
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59 | /** count active observers */ | |
49 |
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60 | let listeners = 0; | ||
50 |
let results: PromiseOrValue<T[]> = |
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61 | let results: PromiseOrValue<T[]> = []; | |
51 |
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62 | |||
52 | const data = observe<OrderedUpdate<T>>(({ next, complete, error }) => { |
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63 | const data = observe<OrderedUpdate<T>>(({ next, complete, error }) => { | |
53 | const processResults = (items: T[]) => |
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64 | const processResults = (items: T[]) => | |
54 | items.forEach((item, newIndex) => next({ item, newIndex, prevIndex: -1 })); |
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65 | items.forEach((item, newIndex) => next({ item, newIndex, prevIndex: -1 })); | |
55 |
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66 | |||
56 | try { |
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67 | try { | |
57 | if (results === pending) |
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68 | // is there are no active observers here, we need to query actual | |
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69 | // data from the store. | |||
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70 | if (listeners === 0) | |||
58 | results = store.query(query, options); |
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71 | results = store.query(query, options); | |
59 |
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72 | |||
60 | if (isPromise(results)) { |
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73 | if (isPromise(results)) { | |
@@ -74,8 +87,14 export const queryEx = <T, Q, O>(store: | |||||
74 | const updates = observe<OrderedUpdate<T>>(({ next, complete, error, isClosed }) => { |
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87 | const updates = observe<OrderedUpdate<T>>(({ next, complete, error, isClosed }) => { | |
75 | try { |
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88 | try { | |
76 | if (!isClosed() && isDjObservableResults<T>(results)) { |
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89 | if (!isClosed() && isDjObservableResults<T>(results)) { | |
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90 | // subscribe fot the changes | |||
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91 | listeners++; | |||
77 | const h = results.observe((item, prevIndex, newIndex) => next({ item, prevIndex, newIndex }), includeUpdates); |
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92 | const h = results.observe((item, prevIndex, newIndex) => next({ item, prevIndex, newIndex }), includeUpdates); | |
78 |
return () => |
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93 | return () => { | |
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94 | // unsubscribe from changes | |||
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95 | listeners--; | |||
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96 | h.remove(); | |||
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97 | }; | |||
79 | } else { |
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98 | } else { | |
80 | complete(); |
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99 | complete(); | |
81 | } |
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100 | } |
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